tag:blogger.com,1999:blog-34273715165054370502024-03-18T02:48:02.789-07:00Gems and GemstonesThis describes hunting for gems and gemstones.Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.comBlogger51125tag:blogger.com,1999:blog-3427371516505437050.post-40180978938118062802012-08-09T07:19:00.001-07:002012-08-09T07:19:27.152-07:00New Jersey Gemstones<div dir="ltr" style="text-align: left;" trbidi="on">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Tumbled_gemstone_pebbles_arp.jpg/490px-Tumbled_gemstone_pebbles_arp.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Tumbled_gemstone_pebbles_arp.jpg/490px-Tumbled_gemstone_pebbles_arp.jpg" width="326" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A variety of tumbled gemstones<br /><span style="background-color: white; font-family: sans-serif; font-size: 12.571428298950195px; line-height: 19.190475463867188px; text-align: start;">Scanned by Adrian Pingstone</span>
</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://www.galleries.com/Amber">Amber</a> that has been preserved since the age of dinosaurs is
found in several places in <st1:state><a href="http://www.state.nj.us/dep/njgs/">New Jersey</a></st1:state>
where there are Cretaceous rocks one of these places in the area around <st1:place>Sayreville</st1:place>
although they can be found scattered throughout the <a href="http://www.ucmp.berkeley.edu/mesozoic/cretaceous/cretaceous.php">Cretaceous</a> rocks and
various localities throughout southern <st1:state>New Jersey</st1:state>.
Although there are several deposits of Cretaceous aged rocks in the United
States Amber is only found with appreciable quantities in <st1:state>New
Jersey</st1:state>. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Amethyst is found in the many trap ridges of <st1:state>New
Jersey</st1:state> in both the area of the <st1:place>Palisades</st1:place>
and in the <st1:place><st1:placename>Ramapo</st1:placename> <st1:placetype>Mountains</st1:placetype></st1:place>. This variety of quartz is usually found in
the cavities in the rock. Many other minerals of the zoisite family are also
associated with traprock quarries.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
In the past there was extensive zinc mining activity in <st1:city>Franklin</st1:city>
and Sterling Hill in Ogdensburg that produced large quantities of zinc
minerals. The mine dumps in these areas
are one of the most noted areas in the United States that have produced
fluorescent minerals. Some of these minerals
are gemstones in their own right notably rhodonite and sphalerite. In addition <st1:place><st1:placename>Sussex</st1:placename>
<st1:placetype>County</st1:placetype></st1:place> is also known for producing
other minerals including <span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">aragonite, corundum, garnet, pyrrhotite,
rhodonite, spinel, tourmaline and williamsite.<o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<st1:place><st1:placename><span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">Bergen</span></st1:placename><span style="background-color: white; background-position: initial initial; background-repeat: initial initial;"> </span><st1:placetype><span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">County</span></st1:placetype></st1:place><span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">
has produced amethyst, natrolite and opal that are found in the county’s trap ridges.<o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<st1:place><st1:placename><span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">Mercer</span></st1:placename><span style="background-color: white; background-position: initial initial; background-repeat: initial initial;"> </span><st1:placetype><span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">County</span></st1:placetype></st1:place><span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">
has been known to produce albite, calcite, chabazite, datolite, natrolite,
stilbite and tourmaline. Calcite, chabazite and datolite are produced from the
trap ridges in the county.</span><o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
In the far southern part of <st1:state>New Jersey</st1:state>
can be found quartz crystals that are called by many <st1:place>Cape May</st1:place>
diamonds although the source of these stones remains unknown it is thought they
are washed down from some underwater formation further upstream in the <st1:place>Delaware
River</st1:place>. They are found on
the beaches of <st1:place>Cape May</st1:place> and surrounding communities at
the mouth of the river. The same area also produces jasper. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Corundum has been found in <st1:place><st1:placename>Sussex</st1:placename>
<st1:placetype>County</st1:placetype></st1:place> associated with the <st1:city>Franklin</st1:city>
limestone as almost perfect crystals seen in cavities in the limestone. These stones are blue, grey and red that in
some places are clear enough to be cut into gems. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Other counties where gemstones can be found include:</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">Middlesex - marcasite, petrified wood, pyrite</span><br />
<br />
<span style="background: white;">Morris - carnelian,
serpentine</span><br />
<br />
<span style="background: white;">Passaic - agate,
amethyst, carnelian, chabazite, datolite, heulandite, pectolite, prehnite</span><br />
<br />
<span style="background: white;">Sussex - aragonite,
corundum, garnet, pyrrhotite, rhodonite, spinel, tourmaline, williamsite</span><br />
<br />
<span style="background: white;">Union - calcite,
chalcedony, prehnite, sphalerlite</span><br />
<br />
<span style="background: white;">Warren - calcite,
chalcedony, garnet, molybdenite, prehnite, serpentine, sphalerlite<o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">Most of the collecting sites are located in </span><st1:place><span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">Northern
New Jersey</span></st1:place><span style="background-color: white; background-position: initial initial; background-repeat: initial initial;">. Many of
these sites are found at old mines or rockcuts.</span><o:p></o:p></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com15tag:blogger.com,1999:blog-3427371516505437050.post-50581893490257365522012-07-24T17:06:00.000-07:002012-07-24T18:46:41.842-07:00The Great Arizona Diamond Swindle<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/1/16/Shiprock_NM.jpg/413px-Shiprock_NM.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/16/Shiprock_NM.jpg/413px-Shiprock_NM.jpg" width="275" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ship Rock close to the diamond fields</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The guys that dreamed up the Great Arizona Diamond <a href="http://www.bing.com/Dictionary/search?q=define+swindle&qpvt=Swindle&FORM=DTPDIA">Swindle</a>
sure did a good job of it, and one that sucked in some smart money from both
coasts. Its locality was way out in the
boonies of <st1:state><a href="http://www.newmexico.gov/">New Mexico</a></st1:state>. Bluntly it was salted with uncut stones from <st1:place>Africa</st1:place>
where vast amounts of diamonds were found in the newly discovered kimberlite
deposits. The so-called rubies that
accompanied the diamonds turned out to be garnets that were mistaken for
rubies. The <a href="http://en.wikipedia.org/wiki/Swindler">swindlers</a> salted so many diamonds of the property that even after
the swindle was exposed people were still finding diamond crystals on the site.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This was a well organized swindle based on the idea in many
American’s heads that the West was a treasure house of riches waiting to be
tapped. At the time companies were
organized to tap these riches, and the locality the swindlers chose in <st1:state>New
Mexico</st1:state> was made for a swindle. At this locality there were not only
diamonds, but rubies, emeralds and sapphires too. This scheme got off the ground in 1870 that
was represented in <st1:city>San Francisco</st1:city> by
Phillip Arnold and John B. Slack who claimed to have found precious gems in the
<st1:place><st1:placetype>Territory</st1:placetype> of <st1:placename>New
Mexico</st1:placename></st1:place>. On
their part they showed off more then 80,000 carats of rubies and a large
quantity of diamonds including one crystal weighing 108 carats.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
A large group of investors visited the diggings and
collected a large number of gemstones that were literally scooped off the
ground, and returned to <st1:city>San Francisco</st1:city>
where the gems were put on display so other suckers could be reeled into the
scheme. At the time someone remarked it was not expected they could pick them
up by the bushel, but there they were.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
They even roped in the Federal Government because on <st1:date day="10" month="5" year="1872">May 10, 1872</st1:date> a bill was passed in
Congress in the interests of the diamond miner who had made the discovery.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
A larger expedition was planned that included a mining
expert that had graduated from the Royal School of Mines in <st1:place><st1:city>Freiberg</st1:city>,
<st1:country-region>Germany</st1:country-region></st1:place>. This expedition was expected to last for
sixty days. This expedition left <st1:place><st1:city>Rawlings</st1:city>,
<st1:state>Wyoming</st1:state></st1:place> on <st1:date day="28" month="5" year="1873">May 28, 1873</st1:date> going southwest to the gem mines, but after a
while they claimed they had lost their way and proceeded northwest for several
days. Some of the party began to doubt
the truth od the scheme, but finally after a circuitous route then finally
arrived at the site, and the mountain promised to be a real Golconda. Everybody found gems, and gems aplenty with
their hope rising accordingly. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
A third party set out late in the season to return to this
fabulous locality, but never got there, and this expedition was abandoned. When Clarence King the head of the United
States Geological Survey heard this third expedition had come to naught he
organized an expedition of his own. It
was King’s expedition that proved the whole scheme was a Humbug and brought the
whole scheme crashing down around the ears of the plotters. It's estimated this pack of crooks got around $750,000 in 1870s dollars.</div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com1tag:blogger.com,1999:blog-3427371516505437050.post-7157574109058584452012-07-24T07:51:00.001-07:002012-07-24T07:51:03.659-07:00The Diamonds of the Wyoming Craton<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/North_america_terrain_2003_map.jpg/673px-North_america_terrain_2003_map.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="355" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/North_america_terrain_2003_map.jpg/673px-North_america_terrain_2003_map.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Bedrock map of North America USGS</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This is a tale about how riches were overlooked in <st1:state>Colorado</st1:state>,
<st1:state>Montana</st1:state> and <st1:state>Wyoming</st1:state>
by gold seekers in days of yore. In
these three states a whole diamond province has been overlooked in the
kimberlites by the hundreds that underlie these states. The diamonds can also be found in lamproites,
lamprophyres and other cryptovolcanic structures that are associated by the
Wyoming Craton underlying these three states.
Many of the larger targets lie right next to I-80 between <st1:city>Cheyenne</st1:city>
and <st1:city>Laramie</st1:city> that remain
unexplored. This area was originally
discovered by early gold miners who discovered it contained little or no gold
so they passed it on.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Subsequent discoveries indicate this may be one of the most
unexplored diamond provinces in <st1:place>North America</st1:place> where the
diamonds can be found in the carbonate rich sediments found in a Archean
gneiss. More then fifty depressions have
been discovered here suggesting cryptovolcanic activity that lie east of the
State Line diamond district. It is
thought these depressions could be kimberlites containing possibly large
amounts of diamonds. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Ongoing exploration suggests that the Wyoming Craton
contains a world-class diamond province and like the diamond province near <st1:place><st1:city>Marathon</st1:city>,
<st1:state>Ontario</st1:state></st1:place> also contains large deposits of
colored gemstones as rubies and sapphires.
This craton is found covering a large portion of <st1:country-region>Canada</st1:country-region>.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The Wyoming Craton aside from covering several western
states also includes exposures in <st1:state>Alberta</st1:state>
and <st1:state>Saskatchewan</st1:state>. Diamonds have
been discovered in both the kimberlites and lamprophyres in <st1:state>Montana</st1:state>,
<st1:state>Wyoming</st1:state>, <st1:state>Colorado</st1:state>,
<st1:state>Kansas</st1:state> and <st1:state>Nebraska</st1:state>
as well as <st1:country-region>Canada</st1:country-region>.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Another potential place where you can look is in any
conglomerates that are derived from the lamprophyres and kimberlites of the Wyoming
Craton. One of my prospecting buddies
has found a diamond deposit like this near <st1:place><st1:city>Marathon</st1:city>,
<st1:state>Ontario</st1:state></st1:place>.
Another Canadian prospecting buddy that lives in western <st1:state>Ontario</st1:state>
has also found probable diamonds in his part of the province.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
It isn’t just diamonds that can be found there; recently one
of the world’s largest deposits of rare earth metals was found in
Nebraska, When you start poking around
in this ancient craton you never know what you’re likely to find.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The Wyoming Craton has the greatest southwestern outcrops of
Archean rocks in <st1:place>North America</st1:place>. Theoretically terranes like this have deep
roots in the lithosphere that according to Clifford’s rule this deep keel is
necessary for the formation of kimberlites with their association with
diamonds. Although this terrane wasn’t
deformed during the </div>
<div class="MsoNormal">
Ancestral Rockies Orogeny it was pervasively deformed during
the Laramide Orogeny and one theory has it that its deep keel was removed
partially or wholly allowing it to be deformed during the Cretaceous or later. <o:p></o:p></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com2tag:blogger.com,1999:blog-3427371516505437050.post-76351874970808790242012-07-23T13:58:00.003-07:002012-07-23T13:58:17.181-07:00Finding Diamonds in California<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://www.freeipadwalls.com/wp-content/gallery/simple/Uncut%20Diamonds.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://www.freeipadwalls.com/wp-content/gallery/simple/Uncut%20Diamonds.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Uncut diamonds</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
From the earliest days of the <a href="http://en.wikipedia.org/wiki/California_Gold_Rush">California Gold Rush</a> <a href="http://en.wikipedia.org/wiki/Diamond">diamonds</a>
were found in the tailraces of sluice boxes that were used for gold
washing. Diamonds were found not only in
recent stream gravels but much older gravel that was buried under layers of
lave and tuff from ancient volcanic activity as fossilized stream channels that
ran along the mountains from north to south.
These stream channels indicated an ancient stream flow that was almost
at right angles to the present day flow.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The biggest problem with <st1:state>California</st1:state>
diamonds is there just are not enough to make going after them profitable. Most
of the stones have been found as a result of gold washing operations in both
present day streams and in the fossilized beds of earlier streams. Many of the
diamonds were destroyed by the use of stamp mills used the breakup the gold ore
retrieved from the <a href="http://www.thefreedictionary.com/fossilized">fossilized</a> streambeds. Their presence was noted as fragments
seen in the gold ore. The diamonds that were recovered from ore were for the
most part small or <a href="http://en.wikipedia.org/wiki/Diamond#Industrial-grade_diamonds">industrial grade diamonds</a>. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
As early as 1853 diamonds were discovered on top of <st1:place><st1:placename>Table</st1:placename>
<st1:placetype>Mtn.</st1:placetype></st1:place> about thirteen miles north of
Oroville on state Highway 70 close to the ghost town of Cherokee. It was in the gold diggings surrounding the
town that reportedly more then 300 diamonds were found most of them being of
industrial grade. Claims have been made
that at the time this was the largest discovery of diamonds made in <st1:place>North
America</st1:place>. This has been
exceeded with the discovery of several diamond producing areas in <st1:country-region>Canada</st1:country-region>.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Cherokee was the site of the only diamond mine in <st1:state>California</st1:state>,
and it was here the first diamonds were found.
Mike Maher discovered a perfect blue diamond when he was cleaning out
his sluice box in 1866. Other diamonds
were found here with one of them weighing six carets, but because gold was the
primary concern it is unknown how many millions of dollars worth were discarded
with the mine tailings produced by the hydraulicing for gold with high pressure
jets of water that washed away the gold ore.
</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The fact that diamonds do occur in <st1:state>California</st1:state>
is well attested to in newspapers and scientific journals. In some cases however it is readily apparent
that many of these so-called diamonds were in fact quartz crystals that had
become rounded because of stream action.
One such quartz crystal had been used as a marker in a game of marbles
where it show several percussion marks that were the result of being hit by
marbles. A diamond would not show such
percussion marks, but would rather cleave into pieces instead waiting to be
found in the sluice boxes at work in the area.</div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com1tag:blogger.com,1999:blog-3427371516505437050.post-16681292900159662982012-07-22T16:22:00.001-07:002012-07-22T16:22:05.859-07:00The Georgia Marvel and other would be gemstones<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c3/Corundum-280372.jpg/476px-Corundum-280372.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c3/Corundum-280372.jpg/476px-Corundum-280372.jpg" width="317" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A large crystal of sapphire from Madagascar<br />Photo by Rob Lavinsky </td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This was found in a stream in the <st1:place>Blue Ridge
Mountains</st1:place> of <st1:country-region>Georgia</st1:country-region>
in 1883 and was purported to be a sapphire worth $50,000 by its finder who was
assured of its authenticity by two different southern jewelers. This fabulous find was also known as the Blue
Ridge Sapphire. The jewelers had arrived
at a value for the stone based on its weight of several carats. Eventually this stone was proved to be a hunk
of rolled blue-bottle glass that took coating it onto some platinum wire to
convince its finder.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This is a glaring example of how little the average person
knows about gems and it seems that fallacy more then truth is known by the
general public. One of these fallacies
is the belief that any stone that can be scratched by a file has to be
glass. Another is that is when a stone
is hit with a hammer it’s a fake. These
practices have led to the destruction of many valuable gems.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The <st1:country-region>United States</st1:country-region>
has an abundance of all types of gemstones that has never been appreciated by
the average person. In many cases these
gems have been produced as a byproduct of other mining operations where many of
them have slipped through the operation to be lost. Many of the stones that were saved were
discovered in places where gold was being washed with the miners being
attracted to a gem because it was a shiny pebble.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Gold washing was not limited to the western US, but was also
practiced in the South starting in the early 1800 with the discovery of gold in
<st1:state>North Carolina</st1:state>. It is difficult today to appreciate the size
and scope of these southern gold deposits that ran through the <st1:place>Piedmont</st1:place>
and <st1:place>Blue Ridge Mountains</st1:place>. In many cases the stream banks for miles were
covered with mine tailings. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The gold wasn’t limited to placer deposits, but many mines
were also producing lode gold. Many of
these mines were destroyed during the Civil War. Recently the Haile Mine in <st1:state>South
Carolina</st1:state> was found to have reserves of gold exceeding
3,000,000 ounces. A Canadian mining
company is in the process of reopening this mine.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Another of these wonders was a stone weighing more then nine
ounces that was discovered near <st1:place><st1:city>Gibsonville</st1:city>, <st1:state>North
Carolina</st1:state></st1:place> that was deemed to be a real emerald by some
local expert by some “local expert.” A
microscopic examination of this stone contained numerous small sparkles of
light that were thought to be tiny diamond crystals. This stone was eventually proved to be a
quartz crystal having long hail-like crystals of hessonite and actinolite that
also had a series of small bubbles in a stream-like pattern filled with liquid
that sparkled in the light like diamonds.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
In truth the <st1:country-region>United States</st1:country-region>
has produced virtually all the precious and semi-precious stones in the
world. For the most part these stones
remain in the ground through lack of interest of outright ignorance. There is also a prevalent belief that gems
come from some far-off romantic place that it is difficult to reach from here. </div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com4tag:blogger.com,1999:blog-3427371516505437050.post-26535856734100287662012-07-21T13:08:00.000-07:002012-07-21T13:08:10.465-07:00The easy way of Identifying your gemstones and minerals<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Semi-precious_gemstones.jpg/800px-Semi-precious_gemstones.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Semi-precious_gemstones.jpg/800px-Semi-precious_gemstones.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Semi precious gemstones<br />Photo by Mauro Cateb</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
All gemstones are minerals, but not all minerals are
gemstones, so the limited knowledge imparted here can be used on both gemstones
and minerals. If you can’t tell what
kind of gems you own don’t feel bad because there have been plenty of emperors
and kings that didn’t have a clue about what kind of stones they had in their
own crown. A good example of this is the
Black Prince’s Ruby that resided in the Crown of England for hundreds of years
before somebody found out it was really a mineral called “<a href="http://www.gemstone.org/index.php?option=com_content&view=article&id=124:sapphire&catid=1:gem-by-gem&Itemid=14">spinel</a>.”
This is a stone that looks like a ruby
but is a much less expensive stone then real ruby. Clear white <a href="http://www.galleries.com/Topaz">topaz</a> is often mistaken for <a href="http://en.wikipedia.org/wiki/Diamond">diamond</a> and in the past many
large diamonds have been found to be really topaz. Identifying these stones is in the realm of
the <a href="http://www.gia.edu/">gemologist</a> who is specially trained to
identify gemstones.</div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/2/2c/Corundum-215478.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/2/2c/Corundum-215478.jpg" width="325" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A translucent ruby<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
There are several stones that are treated as gemstones, but
aren’t. Amber is a glaring example of
this, a stone that is treated as a gem but in reality is fossilized tree sap
having many inclusions of insects and other organic matter. Petrified wood is another example that is
often beautiful and is treated by many as a gemstone, but isn’t. Jet, the black stone is actually a variety of
coal and far from the definition of a gemstone, as are pearls. Pearls have the distinction of being the most
valuable stone, but they aren’t gemstones either.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Identifying gemstones and minerals is really a process of
the elimination, for instance if you are presented with a green clear gemstone
it is not apt to a ruby. More than likely it is emerald, but you really can't
be sure without further tests. There is a variety of garnet called <a href="http://www.gemstone.org/index.php?option=com_content&view=article&id=108:sapphire&catid=1:gem-by-gem&Itemid=14">demantoid</a>
that is also green and is often mistaken for an emerald. One of the most
important tests that are used in mineral identification is the color of the
stone.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://en.wikipedia.org/wiki/Hardness">Hardness</a>
is another criterion that is used. This is based on the Moh’s hardness scale
that ranges from 1 to 10 with diamond being the hardest and soapstone the
softest. Most stones that are used in making jewelry are harder than seven on
the Moh’s scale even though some stones that are as soft as three on the Moh’s
scale are faceted for collectors. You can buy hardness testing kits or make
your own from various minerals that work’s as good as store bought.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/e/ea/Turquoise-29507.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="331" src="http://upload.wikimedia.org/wikipedia/commons/e/ea/Turquoise-29507.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Turquoise from Mojave County, California<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The <a href="http://www.thefreedictionary.com/looks">looks</a>
of the stone are important is it transparent, translucent or opaque. Transparent means can you see through the
stone so things can be seen clearly that are behind the stone. Translucent means does light pass through the
stone, but you can’t make out objects that are in back of the stone. Opaque means light doesn’t pass through the
stone, and you can’t see through it.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Streak is literally a thin mark of the mineral or
gemstone composed of very fine powder left on a piece of unglazed porcelain
colored either black or white. Black is
often used to test for gold and other precious metals when it is known as a
“Touchstone.” It is often used in
conjunction with acid to see if there is a reaction between the streak and the
acid. The karat weight of gold can be
determined by treating its streak with various concentrations of nitric acid. </div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/0/0d/Streak_plate_with_Pyrite_and_Rhodochrosite.jpg/792px-Streak_plate_with_Pyrite_and_Rhodochrosite.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="302" src="http://upload.wikimedia.org/wikipedia/commons/thumb/0/0d/Streak_plate_with_Pyrite_and_Rhodochrosite.jpg/792px-Streak_plate_with_Pyrite_and_Rhodochrosite.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">2x2 inch black and white streak plates, White is pyrite and black is rhodochrosite</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
We sell streak plates: <b><a href="http://www.blogger.com/blogger.g?blogID=5678139710237475804#editor/target=post;postID=7373246063233499798">Click Here</a></b> </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://academic.brooklyn.cuny.edu/geology/grocha/mineral/cleavage.html">Cleavage
and fracture</a> are other important tests.
Fracture is most important for quartz gemstones that break in a
Concoidal fracture that looks like little clam shells. Some minerals like jade have a hackly
fracture i.e. a rough appearance. Some
stones have a pronounced cleavage like topaz or diamond. Topaz is especially prone to a perfect basal .
cleavage causing it to be a poor gemstone.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="file:///C:/Documents%20and%20Settings/TEMP/My%20Documents/BLOGS/GEMSTONES/MISC/en.wikipedia.org/wiki/Specific_gravity">Specific Gravity</a>
was discovered by <a href="http://en.wikipedia.org/wiki/Archimedes'_screw">Archimedes</a>
when he was tasked to find out if a gold smith cheated the Tyrant of Syracuse
when he was making a golden crown for the tyrant. This was a job that required quite a lot of
forelock tugging on the part of Archimedes until he finally threw his hands up
and decided to take a hot bath. His slave girl filled the bathtub to full of
hot water so on Archimedes claimed into the tub it overflowed. He had
discovered the principle of specific gravity, and with that he jumped out of
the bathtub and went streaking through the town agora of <st1:city>Syracuse</st1:city>
yelling at the passersby <st1:city>Eureka</st1:city>, <st1:city>Eureka</st1:city>
that means I have found it, I have found it. They all thought he had gone nuts,
and if it wasn't for the fact his brother-in-law was the tyrant he will
probably been slapped in jail.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
What Archimedes discovered was the body would displace an
equal amount of water according to its volume, or in modern terms its weight
per cubic centimeter. This is normally taken by first weighing the object in air
and then weighing in water. The difference is its Specific Gravity. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<!--[if gte vml 1]><v:oval id="_x0000_s1026" style='position:absolute;
margin-left:7in;margin-top:235.8pt;width:1in;height:1in;z-index:1'/><![endif]--><!--[if !vml]--><span style="height: 98px; margin-left: 671px; margin-top: 313px; mso-ignore: vglayout; position: absolute; width: 98px; z-index: 1;"><img height="98" src="file:///C:/DOCUME~1/TEMP/LOCALS~1/Temp/msohtml1/01/clip_image001.gif" v:shapes="_x0000_s1026" width="98" /></span><!--[endif]-->These are some simple tests that can
help with gemstone or mineral identification there are others that are far more
complicated that can be used in conjunction with the simple tests. Although
there are over 2000 recognized minerals in the world there are only about 300
that are common rock forming minerals that you are apt to encounter in the
field. A good source of information about most minerals can be found at <a href="http://www.mindat.org/">www.mindat.org</a>. </div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com1tag:blogger.com,1999:blog-3427371516505437050.post-14666695127892349232012-06-28T11:36:00.002-07:002012-06-28T11:36:53.702-07:00What Diamond Crystals look Like<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/a/a6/Diamond-249291.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="366" src="http://upload.wikimedia.org/wikipedia/commons/a/a6/Diamond-249291.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Interpenetrating cubes of diamond<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The word morphology means what it
looks like. Diamond crystals are a good
example of this as in the growth process they are able to take on many
guises. They all however are caused by
the basic shape of the carbon cell that controls the diamond growth. The carbon cell is used to build the diamond
crystal or stated in another way a diamond molecule. These carbon cells are deposited onto the
nucleus of the diamond one layer at a time until the diamond finishes
growing. In its purest form a diamond
crystal is cubic like a crystal of sugar.
The addition of various elements however causes a diamond to morph into
different shapes or colors.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The most common of these shapes are the cubic form that is square
like a salt crystal or the octahedron which is two pyramids stuck together base
to base. From this simple crystal form
the shape of a diamond becomes more complex. This is caused by many different physical
process; the most common being the physical space allotted to the diamond
crystal to grow. If this allotted space
is cramped and not shaped like a typical space the diamond crystal will grow
into the shape of the space. Something that will further complicate the
final shape of the diamond crystal that is delivered to the surface of the
Earth is the dissolution of the diamond in carbonate or silicate bearing water
at the pressure-temperature conditions encountered in the diamond stability
field. This was established
experimentally by <span style="color: #292526; mso-bidi-font-weight: bold;">Alexander
F. Khokhryakov and Yuri N. Pal.Yanov of the Siberian Branch of the </span><st1:place><st1:placename><span style="color: #292526; mso-bidi-font-weight: bold;">Russian</span></st1:placename><span style="color: #292526; mso-bidi-font-weight: bold;"> </span><st1:placetype><span style="color: #292526; mso-bidi-font-weight: bold;">Academy</span></st1:placetype></st1:place><span style="color: #292526; mso-bidi-font-weight: bold;"> of Science in </span><st1:city><st1:place><span style="color: #292526; mso-bidi-font-weight: bold;">Novosibirsk</span></st1:place></st1:city><span style="color: #292526; mso-bidi-font-weight: bold;"> </span><st1:country-region><st1:place><span style="color: #292526; mso-bidi-font-weight: bold;">Russia</span></st1:place></st1:country-region><span style="color: #292526; mso-bidi-font-weight: bold;">. <o:p></o:p></span></div>
<div class="MsoNormal">
<span style="color: #292526; mso-bidi-font-weight: bold;"><br /></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/d/d1/Diamond-dimd15b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/d/d1/Diamond-dimd15b.jpg" width="393" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The macle another form of diamond crystal<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="color: #292526; mso-bidi-font-weight: bold;"><br /></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="color: #292526; mso-bidi-font-weight: bold;">One of
the stranger forms of diamond growth is exemplified by the rough diamonds from
the Ekati, Diavik and </span><st1:place><st1:placename><span style="color: #292526; mso-bidi-font-weight: bold;">Snap</span></st1:placename><span style="color: #292526; mso-bidi-font-weight: bold;"> </span><st1:placetype><span style="color: #292526; mso-bidi-font-weight: bold;">Lake</span></st1:placetype></st1:place><span style="color: #292526; mso-bidi-font-weight: bold;"> mines in </span><st1:country-region><st1:place><span style="color: #292526; mso-bidi-font-weight: bold;">Canada</span></st1:place></st1:country-region><span style="color: #292526; mso-bidi-font-weight: bold;">. These diamonds are dug out of the ground
wearing fur coats that are fibrous overgrowths of diamond crystals with a
transparent diamond crystal at the center.
Apparently somebody told these diamonds they were coming from </span><st1:country-region><st1:place><span style="color: #292526; mso-bidi-font-weight: bold;">Canada</span></st1:place></st1:country-region><span style="color: #292526; mso-bidi-font-weight: bold;">, so they came prepared for the
Canadian weather. How this came about
was the diamond crystal had more then one stage of growth. <o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="color: #292526; mso-bidi-font-weight: bold;">There
are one or more generations of crystal growth in most diamond crystals. A diamond crystal can also undergo retrograde
growth where conditions either in the area in the mantle where it was formed or
on its way to the surface in kimberlite magma. Some of these crystals can become bizarre in
their appearance, and some of the more bizarre are what are called skeletal
crystals. Sometimes the diamonds are
etched into more rounded shapes by the action of the chemistry of where they
are formed or transported.<o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="color: #292526; mso-bidi-font-weight: bold;">The
macle is another shape the diamond can naturally take this is a twinned diamond
taking a triangular shape and has two large triangular sides.</span><o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<b><span style="color: #292526;">References:<o:p></o:p></span></b></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoBodyText">
<st1:place>Harlow</st1:place>, George E., The Nature of
Diamonds, <st1:place><st1:placename>American</st1:placename> <st1:placetype>Museum</st1:placetype></st1:place>
of Natural History, © 1995</div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com4tag:blogger.com,1999:blog-3427371516505437050.post-30631306740759458302012-06-28T11:23:00.001-07:002012-06-28T11:23:45.323-07:00How Diamond Crystals Grow<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/d/d1/Diamond-214884.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/d/d1/Diamond-214884.jpg" width="396" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A diamond crystal from Crater of Diamonds State Park, Arkansas<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<br />
<div class="MsoBodyText">
<br /></div>
<div class="MsoBodyText">
Diamonds don’t grow overnight because
in nature their growth proceeds one atom of carbon at a time with four carbon
atoms bound together by chemical bonds.
The natural way that this bonding occurs will normally create a crystal
that is an octahedron in shape. This
shape however can be altered by several different parameters imposed by the
space allocated to the growth of the crystal in the media in which it is
formed. In the process of growing
diamonds are apt to include small crystals of the surrounding material into
their crystal shape. These inclusions
are literally windows into the mantle of the earth that are brought to the
surface when the diamond is carried to the surface of the earth by a kimberlite
or lamproite.</div>
<div class="MsoBodyText">
<br /></div>
<div class="MsoBodyText">
Diamonds are nothing more complicated then a crystal of
pure carbon, and are in fact an allotropic form of an element that can have
other crystalline forms either amorphous as lampblack or as graphite from which
we make pencils. There is another rarer amorphic
form of carbon termed ‘lonsdalite’ that is somewhere between graphite and
diamond in physical structure. Lonsdalite is not a variety of diamond but is
instead a different material. In
lonsdalite there is a repeating networking of carbon atoms that all point in
the same direction rather then alternating back and forth as in a diamond. Its crystals instead of forming cubes or
tetrahedra as the diamond does are instead hexagonal. Although it is often found with diamonds it
is considered to be an allotropic form of carbon formed as the result of shock from
a large meteorite.</div>
<div class="MsoBodyText">
<br /></div>
<div class="MsoBodyText">
From work performed on some of the diamonds from the Ekati
diamond mine in the Northwest Territories of Canada it would appear that the
growth of diamond crystals begin with a small fragment of graphite upon which
the diamond crystals are deposited over time.
A matter of controversy is the actual speed in which diamond crystals
are formed. Experiments in <st1:country-region>Japan</st1:country-region>
with manmade diamond crystals suggest that it is possible to grow a ten caret
crystal in several hundred hours. This
of course is under ideal conditions and in nature would probably take much
longer as the diamond crystal would have to scavenge its carbon atoms from the
surrounding rocks. Carbon is a rare
element in the earth’s rocks. </div>
<div class="MsoBodyText">
<br /></div>
<div class="MsoBodyText">
Most of the carbon available to create a diamond has been
postulated to come from oceanic crust that has been subducted beneath a
continental crust as deceased life forms of coral reefs with the necessary
temperature to cause their disassociation into the components making up the
coral reef. This would be carbon and the
carbonate radical. The calcium or
magnesium from this reaction would be incorporated into the earth’s
mantle. Whatever free carbon remains
from this reaction would be available at this temperature and pressure to form
diamond crystals.</div>
<div class="MsoBodyText">
<br /></div>
<div class="MsoBodyText">
As the diamond crystal grows it is also scavenging other
elements that are incorporated into the crystal as crystal defects. The most common of these elements are
nitrogen and iron. These elements cause
the diamond crystal to become colored with the coloration being dependent upon
the amount of these elements.</div>
<div class="MsoBodyText">
<br /></div>
<div class="MsoBodyText">
<b>References:<o:p></o:p></b></div>
<div class="MsoBodyText">
<st1:place>Harlow</st1:place>, George E., The Nature of
Diamonds, <st1:place><st1:placename>American</st1:placename> <st1:placetype>Museum</st1:placetype></st1:place>
of Natural History, © 1995</div>
<div class="MsoBodyText">
The Nature of Diamonds, <a href="http://www.amnh.org/exhibitions/diamonds/">http://www.amnh.org/exhibitions/diamonds/</a>
</div>
<span lang="EN">Mineralogical Association of
Canada, Editor Lee A. Groat, Geology Of Gem Deposits, Short Course Series,
Volume 37, Yukon Geological Survey, © 2007, Yellowknife, Northwest Territories<o:p></o:p></span><br />
<span lang="EN">Gem Deposits, <a href="http://amonline.net.au/geoscience/earth/gem.htm">http://amonline.net.au/geoscience/earth/gem.htm</a>
<o:p></o:p></span><br />
<span lang="EN">Geology of Gem Deposits, Mineralogical
Association of Canada, Editor Lee A. Groat,</span><span lang="EN"> </span><span lang="EN"><a href="http://www.mineralogicalassociation.ca/doc/promo_SC37.pdf">http://www.mineralogicalassociation.ca/doc/promo_SC37.pdf</a> Volume 37 © 2007<o:p></o:p></span><br />
<div class="MsoBodyText">
<br /></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com0tag:blogger.com,1999:blog-3427371516505437050.post-29713084688403229752012-06-28T11:10:00.000-07:002012-06-28T11:10:03.980-07:00Kimberlite the source for Diamonds<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://upload.wikimedia.org/wikipedia/commons/thumb/a/ac/Diamant_sur_kimberlite_(R%C3%A9publique_d'Afrique_du_Sud)_.JPG/654px-Diamant_sur_kimberlite_(R%C3%A9publique_d'Afrique_du_Sud)_.JPG" imageanchor="1"><img border="0" height="366" src="http://upload.wikimedia.org/wikipedia/commons/thumb/a/ac/Diamant_sur_kimberlite_(R%C3%A9publique_d'Afrique_du_Sud)_.JPG/654px-Diamant_sur_kimberlite_(R%C3%A9publique_d'Afrique_du_Sud)_.JPG" width="400" /></a></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Kimberlite is a potassic volcanic rock best known for
sometimes containing diamonds. It was
originally discovered in <st1:place><st1:city>Kimberly</st1:city>, <st1:country-region>South
Africa</st1:country-region></st1:place> in 1871 hence its name. The miners digging in the “big hole” found a
large diamond weighing 83.5 carets that spawned the South African Diamond
Rush. There have been literally
thousands of kimberlites that have been discovered since the initial discovery
in 1871. Of all the discoveries however
only about one kimberlite in three hundred actually become diamond mines. Diamondiferous kimberlites are actually quite
rare. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
In cross section a kimberlite is a vertically standing
feature called a diatreme in the earth’s crust that is shaped like a big
carrot. Where in the earth’s mantle
kimberlites originate has been a matter of controversy for decades the one
thing we are sure of however that they come from a depth greater then the
so-called diamond window at more then 140 Km below the earth’s surface. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The highly complex volcanics that solidify into kimberlite
or lamproite are not the source of diamonds they are the elevator that brings
them to the surface. The volcanics rise
through a complicated set of cracks and fissures until they near the surface
where their extreme pressure causes them to blast an opening through the
surface called a pipe. In the case of
kimberlites the pipe is carrot shaped, and in lamproites it is shaped like a
champagne glass. </div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/Chimenea_kimberlita.png/800px-Chimenea_kimberlita.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="282" src="http://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/Chimenea_kimberlita.png/800px-Chimenea_kimberlita.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cross section of a kimberlite chimney<br />By <a href="http://commons.wikimedia.org/wiki/User:H_A_A" style="background-color: #f9f9f9; background-image: none; color: #0b0080; font-family: sans-serif; font-size: 12px; line-height: 19px; text-align: -webkit-auto; text-decoration: none;" title="User:H A A">Heriberto Arribas Abato</a></td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Kimberlite and lamproite are similar magmas full of debris
from the mantle of the earth as xenoliths with the actual magma acting as glue
to stick the mass together. Diamonds
found in kimberlites or lamproites are part of the debris brought to the
surface. The magmas are rich in
magnesium and volatile components such as water and carbon dioxide as these volatiles
near the earth’s surface they explode into the characteristic carrot or
champagne craters. At the time of
eruption they also form small conelike features on the surface of the earth
that are quickly eroded away by the process of weathering. Both types of eruption are quite rare and
small in size. They may also occur as
dikes or sills in the country rock which undergoes considerable fracturing as
the magma reaches towards the surface.
The rocks in the lithosphere are very brittle making it easy for
kimberlites to reach the surface. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
There are several different compositions related to
kimberlites and they are named after the predominant mineral. Normally the most abundant mineral associated
with the primary magma is olivine making the kimberlite with olivine known as a
periodotic kimberlite. Other types are
eclogitic, websteritic, sublithospheric and uncertain. Any of these may contain diamonds. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<b>References:<o:p></o:p></b></div>
<span lang="EN">Mineralogical Association of
Canada, Editor Lee A. Groat, Geology Of Gem Deposits, Short Course Series,
Volume 37, Yukon Geological Survey, © 2007, Yellowknife, Northwest Territories<o:p></o:p></span><br />
<span lang="EN">Gem Deposits, <a href="http://amonline.net.au/geoscience/earth/gem.htm">http://amonline.net.au/geoscience/earth/gem.htm</a>
<o:p></o:p></span><br />
<span lang="EN">Geology of Gem Deposits, Mineralogical
Association of Canada, Editor Lee A. Groat,</span><span lang="EN"> </span><span lang="EN"><a href="http://www.mineralogicalassociation.ca/doc/promo_SC37.pdf">http://www.mineralogicalassociation.ca/doc/promo_SC37.pdf</a> Volume 37 © 2007<o:p></o:p></span><br />
<span lang="EN">Industrial Minerals and Rocks,
Page 418, <a href="http://books.google.com/books?id=zNicdkuulE4C&pg=PA417&lpg=PA417&dq=kimberlites+and+the+occurance+of+diamonds&source=bl&ots=Nhqev_Ebqc&sig=WQyRiIxdpBMtnaZWwhGwKC5o1sY&hl=en&ei=csyvSbDZAojWnQfAmpTNBQ&sa=X&oi=book_result&resnum=9&ct=result#PPA418,M1">http://books.google.com/books?id=zNicdkuulE4C&pg=PA417&lpg=PA417&dq=kimberlites+and+the+occurance+of+diamonds&source=bl&ots=Nhqev_Ebqc&sig=WQyRiIxdpBMtnaZWwhGwKC5o1sY&hl=en&ei=csyvSbDZAojWnQfAmpTNBQ&sa=X&oi=book_result&resnum=9&ct=result#PPA418,M1</a>
<o:p></o:p></span><br />
<span lang="EN">Kimberlite, Wikipedia the free
encyclopedia, <a href="http://en.wikipedia.org/wiki/Kimberlite">http://en.wikipedia.org/wiki/Kimberlite</a>
<o:p></o:p></span><br />
<span lang="EN">The Nature of diamonds,
Kimberlites and Lamproites, American Museum of Natoual History, <a href="http://www.amnh.org/exhibitions/diamonds/kimberlite.html">http://www.amnh.org/exhibitions/diamonds/kimberlite.html</a>
<o:p></o:p></span><br />
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com1tag:blogger.com,1999:blog-3427371516505437050.post-4366796706063714402012-06-28T09:49:00.001-07:002012-06-28T09:49:31.787-07:00Inclusions found in Diamonds tell quite a Tale<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/b/bd/DiamanteEZ.jpg/200px-DiamanteEZ.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="380" src="http://upload.wikimedia.org/wikipedia/commons/thumb/b/bd/DiamanteEZ.jpg/200px-DiamanteEZ.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A flaw seen near the center of a diamond crystal - Wikipedia</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The<a href="http://en.wikipedia.org/wiki/Diamond_flaws"> inclusions</a> found in a natural diamond are a window on
the interior of the earth. Basically
there are two types of inclusions found in a diamond. The first type is a Syngenetic inclusion that
was formed in the natural process of crystallization was ongoing. The second type is the Epigenetic inclusion
that was formed after the diamond was made.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The most serious flaw is a cleavage that can compromise the
stability of a diamond. These cleavage
cracks are straight. If they are serious
enough they can split a diamond along the cleavage crack. The diamond cutter often takes advantage of
this flaw to cleave a diamond into two or more pieces. They will also cause a diamond to split if
accidentally subjected to a sudden high pressure event.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Bearding is hair-like cracks that often happen during the
cutting of a diamond usually occurring around the girdle. This is the area in the Anatomy of a Diamond
where the setting prongs grasp the diamond.
Sometimes this flaw is also called “girdle fringes.” </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Growth lines are sometimes called grain lines they typically
form while the diamond crystal is growing.
If irregular crystallization occurs this is often a reason why these
lines form. If they are colorless they
don’t affect the diamond’s clarity.
Sometimes though they are white or colored they are more visible and do
affect the value of the diamond.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The next group of inclusions is man made that called ‘laser
lines’ and can come from several different operations on the diamond. The most common type is where the diamond
cutter has used a laser for removing dark or prominent inclusions from the
diamond. The second most common is from
the use of a microprobe used to analyze the tiny crystals of other minerals
that are Syngenetic inclusions in the diamond.
</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Feathers derive their name because they actually look like
small feathers inside a diamond. These
seem to be Syngenetic tiny cracks that formed with the diamond. Small feathers seem to be harmless, but if
they reach the surface of the diamond crystal then can increase the risk of
breakage. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The last group of inclusions is definitely Syngenetic in
nature; they are called pinpoints. These
are crystals of other minerals that were trapped inside the diamond crystal as
it formed. These are true windows into
the interior of the earth as they were formed billions of years ago. These same crystals are used by geochemists
using a microprobe to determine their composition, and learn about the interior
of the earth. The most common inclusions
are pyrope garnet, pyrite, zircon, eclogite and other rare minerals. Sometimes an inclusion inside a diamond is
what is termed a negative crystal which is just a void looking like a diamond
crystal. Other inclusions are minute drops
of liquid usually water or liquid carbon dioxide.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Flaws are the characteristic inclusions found in a
diamond. They are called flaws because
their presence means that the diamond is not perfect. These inclusions act like fingerprints
because no two of them are the same they are used to identify individual
diamonds if they are lost or stolen.
Other inclusions affect a diamond’s clarity causing it to be less
brilliant as they interfere with the light as it passes through a diamond. There are other inclusions that can cause a
diamond to fracture if it is subjected to a sudden sharp blow.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<b>References:<o:p></o:p></b></div>
<div class="MsoNormal">
<br /></div>
<span lang="EN">Mineralogical Association of
Canada, Editor Lee A. Groat, Geology Of Gem Deposits, Short Course Series,
Volume 37, Yukon Geological Survey, © 2007, Yellowknife, Northwest Territories<o:p></o:p></span><br />
<span lang="EN">Gem Deposits, <a href="http://amonline.net.au/geoscience/earth/gem.htm"><span style="font-family: Arial; font-size: 9.0pt;">http://amonline.net.au/geoscience/earth/gem.htm</span></a>
<o:p></o:p></span><br />
<span lang="EN">Geology of Gem Deposits, Mineralogical
Association of Canada, Editor Lee A. Groat,</span><span lang="EN"> </span><span lang="EN"><a href="http://www.mineralogicalassociation.ca/doc/promo_SC37.pdf"><span style="font-family: Arial; font-size: 9.0pt;">http://www.mineralogicalassociation.ca/doc/promo_SC37.pdf</span></a> Volume 37 © 2007<o:p></o:p></span><br />
<span lang="EN">Industrial Minerals and Rocks,
Page 418, <a href="http://books.google.com/books?id=zNicdkuulE4C&pg=PA417&lpg=PA417&dq=kimberlites+and+the+occurance+of+diamonds&source=bl&ots=Nhqev_Ebqc&sig=WQyRiIxdpBMtnaZWwhGwKC5o1sY&hl=en&ei=csyvSbDZAojWnQfAmpTNBQ&sa=X&oi=book_result&resnum=9&ct=result#PPA418,M1"><span style="font-family: Arial; font-size: 9.0pt;">http://books.google.com/books?id=zNicdkuulE4C&pg=PA417&lpg=PA417&dq=kimberlites+and+the+occurance+of+diamonds&source=bl&ots=Nhqev_Ebqc&sig=WQyRiIxdpBMtnaZWwhGwKC5o1sY&hl=en&ei=csyvSbDZAojWnQfAmpTNBQ&sa=X&oi=book_result&resnum=9&ct=result#PPA418,M1</span></a>
<o:p></o:p></span><br />
<div class="MsoNormal">
<span lang="EN">Kimberlite,
Wikipedia the free encyclopedia, <a href="http://en.wikipedia.org/wiki/Kimberlite"><span style="font-family: Arial; font-size: 9.0pt;">http://en.wikipedia.org/wiki/Kimberlite</span></a><o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span lang="EN">Diamond
Inclusions, <a href="http://jewelry.about.com/cs/diamondclarity/a/inclusions.htm">http://jewelry.about.com/cs/diamondclarity/a/inclusions.htm</a>
<o:p></o:p></span></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com2tag:blogger.com,1999:blog-3427371516505437050.post-37875448778306414712012-06-27T20:40:00.003-07:002012-06-27T20:40:57.828-07:00Finding Gemstone Deposits:<div dir="ltr" style="text-align: left;" trbidi="on">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/7/79/Calcite-Corundum-pb51b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/7/79/Calcite-Corundum-pb51b.jpg" width="365" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ruby crystal on calcite<br />photo by Rob Lavinsky</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<a href="http://en.wikipedia.org/wiki/Gemstone">Gems </a>have been prized for thousands of years, for their
color, luster, durability, hardness and their high <a href="http://en.wikipedia.org/wiki/Intrinsic_value_(ethics)">intrinsic value</a> per
volume. They are found in all kinds of
geologic environments of all ages from thousands of million years to recent
times. Gemstones are also found in all
kinds of rocks ranging from igneous to metamorphic to sedimentary and are
classified according to the environment where they were formed. The <a href="http://earthsci.org/mineral/mindep/depfile/gem_dep.htm">deposits</a> are rare because of the
<a href="http://en.wikipedia.org/wiki/Geology">geological conditions</a> needed to form them are exceptional. For example, in order for the Emerald to form
the beryllium from which it is made has to come in contact with chromium or
vanadium. These elements travel in
entirely different geochemical circles that are the exception rather than the
rule.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
It is important to realize that like any other <a href="http://en.wikipedia.org/wiki/Commodity">commodity</a>,
gems are subject to the laws of supply and demand. Even though the demand for gems remains about
the same the supplies are becoming depleted.
Many of the gems especially the colored variety are mined in <st1:place>Third
World</st1:place> countries by artesianal methods, i.e. by hand. In any of these countries the discovery of
the new deposit often leads to a local prosperity, but many of these stones
become involved in the <a href="http://wn.com/Illegal_Trade">illegal trade</a> that is being used to finance <a href="http://en.wikipedia.org/wiki/Terrorism">terrorism</a>.</div>
<div class="MsoNormal">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/8/8c/Corundum-191826.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/8/8c/Corundum-191826.jpg" width="201" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Sapphire crystal<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<br />
<br /></div>
<div class="MsoNormal">
<b><a href="http://earthsci.org/mineral/mindep/depfile/mag_dep.htm">Magmatic Deposits</a>:<o:p></o:p></b></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
These deposits of gemstones are volcanic in origin and are
formed deep within the Earth’s crust.
Gemstones from this origin have formed over 100 Km below the surface and
are brought to the surface as the result of magma intrusions or lava
flows. Diamonds are one type of this
deposit that has formed from 100 to 150 Km below the surface. These gemstones are found in potassium rich
stone called “kimberlite” that is brought to the surface in an explosive eruption
that proceeds at near supersonic speeds.<b> </b>There seems to be a rule known as
<a href="http://gemology.knoji.com/applying-cliffords-rule-to-finding-diamonds/">Clifford's rule</a> <span style="background-color: white;">that these eruptions take place in <a href="http://en.wikipedia.org/wiki/Archean">Achaean</a> terranes or come up
through younger terranes overlying Achaean terrenes.</span><span style="background-color: white;"> </span><span style="background-color: white;">Kimberlite is quite rich in peridot and appears
to be full of <a href="http://www.umanitoba.ca/geoscience/faculty/arc/xenolith.html">xenoliths</a> that are torn off the walls of the magma channel.</span><span style="background-color: white;"> </span><span style="background-color: white;">A cross-sectional view of the kimberlite is
like looking at a carrot.</span><span style="background-color: white;"> </span><span style="background-color: white;">The stone
itself is quite soft and easily eroded away with the diamonds being carried
away with the rest of the erosion products.</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Diamonds are not the only product that is found in a
magmatic deposit so are others stones such as sapphires and zircons. Sapphires are also formed under some very
specific geological conditions the most important one is a magmatic stone that
is low in primary silicates such as basalt.
The sapphires form as crystals in the basalt and they're released as
products of erosion. Although they form
in the basalt they are rarely mined directly.
Zircons are another example of a gemstone that is found in a magmatic
deposit. Once again these gemstones are
not mined directly from the stone that are found as the products of
erosion. In geology zircons are thought
to be forever and the oldest dated minerals in the world are some zircons that
were found in <st1:state>Western Australia</st1:state>
that were dated at 4.5 billion years old.
Zircons are used by <a href="http://en.wikipedia.org/wiki/Category:Geochemists">geochemists</a> worldwide for dating formations of
different ages, and are highly effective in this use.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Some other gemstone minerals that are found in magmatic
deposits include: </div>
<div class="MsoNormal">
Peridot, gem quality olivine usually found in mantle
xenoliths. </div>
<div class="MsoNormal">
Labradorite, found as gem quality grains in some basalts. </div>
<div class="MsoNormal">
Zircon, found as crystals in granite, basalt and the rarer
carbonatites.</div>
<div class="MsoNormal">
Apatite, found as crystals in carbonatites.</div>
<div class="MsoNormal">
Garnets, found as crystals in basalts as xenocrysts and
granite.</div>
<div class="MsoNormal">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/9/9e/Beryl_Smaragd_DSCF0433.jpg/800px-Beryl_Smaragd_DSCF0433.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="266" src="http://upload.wikimedia.org/wikipedia/commons/thumb/9/9e/Beryl_Smaragd_DSCF0433.jpg/800px-Beryl_Smaragd_DSCF0433.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Emerald crystal on calcite<br />Photo by Eva Krocher</td></tr>
</tbody></table>
<br />
<br /></div>
<div class="MsoNormal">
<b><a href="http://hydrothermal%20deposits/">Hydrothermaldeposits</a>:<o:p></o:p></b></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Pegmatites are hydrothermal deposits contain more different
types of gemstones in any other rock.
These are formed from the volatile rich fluids that are found in
pegmatites when they are formed. In some
geological circles pegmatites are called “Giant granite” because they have the
same minerals as granite except the crystals of the individual minerals are
much larger. There are two different
kinds of pegmatites simple and complex; most of the valuable minerals are found
in complex pegmatites. Although many of
these minerals could be classified as gems other minerals found in pegmatites
are the ores for rare metals such as niobium or rare earths. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Depending on the fluids present when the pegmatite is
solidifying different gemstones are deposited.
If the fluid is rich in fluorine topaz will be deposited. A beryllium rich fluid will produce the
mineral beryl in its many forms ranging from aquamarine, emerald, morganite, or
heliodor. Lithium rich fluid is another
possibility depositing spodumene or other lithium rich minerals. Pollucite is deposited from a cesium rich
fluid. In some cases the fluid is rich
in several different elements producing “Tourmaline” a gemstone that is
actually rarer them diamonds. A
manganese rich fluid will cause spessertine garnet to be deposited.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
There are specific zones in a pegmatite where gemstones are
found. Many of them are found in
cavities called “Vugs.” The crystals formed
in this environment are usually clear and well formed. A deposit of this nature containing red and
green tourmaline was discovered in the 1970s at <st1:place><st1:city>Newry</st1:city>,
<st1:state>Maine</st1:state></st1:place> that was worth more then $8 million
from a single vug as large as a bedroom.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
There are other hydrothermal environments that are also
capable of producing gemstones ranging from volcanic rocks to sedimentary
rocks. This is where one is likely to
encounter agates, petrified wood, opal, amethyst as well as a whole plethora of
gems. Turquoise is another mineral
deposited by hydrothermal waters. It is
copper phosphate and its beautiful sky blue botryoidal masses have been admired
for over two thousand years.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<b><a href="http://www.cps-amu.org/sf/notes/b3-3-10.htm">Metamorphic deposits</a>:<o:p></o:p></b><br />
<b><br /></b><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/d/d7/Rough_diamond.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://upload.wikimedia.org/wikipedia/commons/d/d7/Rough_diamond.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Diamond crystal in matrix - USGS</td></tr>
</tbody></table>
<b><br /></b></div>
<div class="MsoNormal">
<br /></div>
The only gem minerals normally found in metamorphic rocks are garnet,
zoisite (variety tanzanite), rubies and emeralds. Rubies are the red variety of the mineral
corundum that is aluminum oxide. These
gems are found in cordierite rich gneiss as well as marble. Sometimes rubies are carried up from the
depths of the earth as xenocrysts in basalt.
Most of the world's emeralds are found in low grade carbonaceous schist
in <st1:country-region>Colombia</st1:country-region>. <span lang="EN">Other
gemstones that occur in metamorphic rocks are <strong><span style="font-weight: normal;">iolite</span> </strong>(the gem-quality
lilac-purple variety of cordierite), <strong><span style="font-weight: normal;">titanite</span> </strong>and <strong><span style="font-weight: normal;">kyanite</span></strong><b>. <o:p></o:p></b></span><br />
<span lang="EN">Jade is another mineral that is
found in high-pressure; low-pressure blue schist metamorphic rocks. There are two entirely different minerals
that are recognized as jade in the trade one of these as jadeite a compact
variety of the mineral pyroxene, and the other is nephrite a compact variety of
the mineral that is derived from tremolite.
Although these minerals are composed of common minerals it takes a very
special environment for them to form.<o:p></o:p></span><br />
<span lang="EN"><br /></span><br />
<b><span lang="EN"><a href="http://en.wikipedia.org/wiki/Sedimentary_exhalative_deposits">Sedimentary deposits</a>:</span></b><span lang="EN"><o:p></o:p></span><br />
<span lang="EN"><br /></span><br />
<span lang="EN">By far the most valuable gemstone
found in sedimentary rock is precious opal.
The largest deposits of this mineral in the world are found in central
Australia. Other deposits are found in
the United States and Mexico. Most opal
is found as a replacement for fossils.
Opal also occurs as replacement beds or blebs in sedimentary rock. A good piece of opal showing good colors can
be as expensive as a diamond.<o:p></o:p></span><br />
<span lang="EN"><br /></span><br />
<b><span lang="EN"><a href="http://en.wikipedia.org/wiki/Placer_deposit">Placer deposits:</a><o:p></o:p></span></b><br />
<span lang="EN"><br /></span><br />
<span lang="EN">In some placer deposits gemstones
are relatively abundant particularly in areas where the local rocks are known
to produce gemstones. This is especially
true in areas underlying by cordierite gneiss or marble. Another area is where gemstone bearing
pegmatites are abundant. Because of
their toughness and hardness gemstones that are eroded from their country rock
tend to remain intact preserving the best gemstones. The same rough and tough treatment these
stones go under as a result of natural processes particularly running water the
weaker and softer stones are broken up leaving behind the highest quality
gemstones. Most of the gemstones in the
world are recovered from placer deposits.
In some cases the work of recovery can be quite primitive; in others the
most modern technology and machinery is used.<o:p></o:p></span><br />
<b><span lang="EN"><br /></span></b><br />
<b><span lang="EN">References:<o:p></o:p></span></b><br />
<span lang="EN"><br /></span><br />
<span lang="EN">Mineralogical Association of
Canada, Editor Lee A. Groat, Geology Of Gem Deposits, Short Course Series,
Volume 37, Yukon Geological Survey, © 2007, Yellowknife, Northwest Territories<o:p></o:p></span><br />
<span lang="EN">Gem Deposits, <a href="http://amonline.net.au/geoscience/earth/gem.htm">http://amonline.net.au/geoscience/earth/gem.htm</a>
<o:p></o:p></span><br />
<span lang="EN">Geology of Gem Deposits, Mineralogical
Association of Canada, Editor Lee A. Groat,</span><span lang="EN"> </span><span lang="EN"><a href="http://www.mineralogicalassociation.ca/doc/promo_SC37.pdf">http://www.mineralogicalassociation.ca/doc/promo_SC37.pdf</a> Volume 37 © 2007<o:p></o:p></span></div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com2tag:blogger.com,1999:blog-3427371516505437050.post-11037842635775341292012-05-19T14:18:00.001-07:002012-06-07T18:52:33.918-07:00Minerals of Litchfield County, Connecticut<div dir="ltr" style="text-align: left;" trbidi="on">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSgMr_XCtZqTSVY27akzSqTQwBDKp2w5OA8l_W2flg_L9eRpzIqhBZFROOmTCc5rgntgQDcIrDywkn-8WfvQT6Bh7PQzy-Ry2x2Y_kT7KCYCKQZXTYaTCJ6hr5BFWjVdGLfCGPJ6DUc4A/s1600/Sample+Stones+021+ilmenite+5-17-2012.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSgMr_XCtZqTSVY27akzSqTQwBDKp2w5OA8l_W2flg_L9eRpzIqhBZFROOmTCc5rgntgQDcIrDywkn-8WfvQT6Bh7PQzy-Ry2x2Y_kT7KCYCKQZXTYaTCJ6hr5BFWjVdGLfCGPJ6DUc4A/s400/Sample+Stones+021+ilmenite+5-17-2012.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Platy ilmenite crystals encrusted on feldspar from Litchfield, Connecticut<br />
Make an offer over $2,500</td></tr>
</tbody></table>
<div class="separator" style="clear: both; text-align: center;">
</div>
<a href="http://en.wikipedia.org/wiki/Litchfield_County,_Connecticut">itchfield County</a>, Connecticut has a very complex geology and a wide variety of minerals that ti date have been largely out of scope to the <a href="http://en.wikipedia.org/wiki/Mineral_collector">mineral collector</a>. It is our aim to make some of these minerals available to the collector. Our first selection of minerals comes from a long abandoned mine in <a href="http://www.litchfieldct.com/">Litchfield</a> , Connecticut that according to the records produced "soapstone" during the 1700s. Some of the minerals found at this locality include such world class specimens as kyanite, ilmenite, magnetite, quartz and many others. There are over two-hundred minerals that have been identified in the county that was the home to over two-hundred mines in the past that have been long since abandoned and mainly forgotten.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/7/76/James_Dwight_Dana_by_Daniel_Huntington_1858.jpeg/230px-James_Dwight_Dana_by_Daniel_Huntington_1858.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/7/76/James_Dwight_Dana_by_Daniel_Huntington_1858.jpeg/230px-James_Dwight_Dana_by_Daniel_Huntington_1858.jpeg" width="333" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">James Dwight Dana in a painting by Danial Huntington - 1858</td></tr>
</tbody></table>
<div style="text-align: center;">
<br /></div>
It is possible our long abandoned mine site is a <a href="http://en.wikipedia.org/wiki/James_Dwight_Dana">Dana Locality</a> because of some mineral specimens that were collected in Litchfield that are now in the collection of the <a href="http://peabody.yale.edu/">Yale Peabody Museum</a> in New Haven, Connecticut including ilmenite of which our locality still has world class specimens in sizes ranging from mere chips to boulders weighing up to several hundred pounds. The size range of the specimens range from micro specimens to boulders that can be used in landscape arrangements.<br />
<br />
We are making these specimens for sale to the mineral collector. You can contact us at: geotekllc@gmail.com for prices and additional information.<br />
<br />
Below are illustrations of some of the specimens we have for sale:<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqEU1Z1ndMir7Xq4no5Qc5sj874qCH_Zt8yxV9ecLJASFJg1QRkRkEPqWmbtSpBQEkmC3SCgLCk_VB02j4pT8ZNf9EEK1pz6Bv3DkyRvnqA6Bznad7TWhFEY4LOIwsPlH2RhduxselnuY/s1600/IMG_1479+ilmenite+003.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqEU1Z1ndMir7Xq4no5Qc5sj874qCH_Zt8yxV9ecLJASFJg1QRkRkEPqWmbtSpBQEkmC3SCgLCk_VB02j4pT8ZNf9EEK1pz6Bv3DkyRvnqA6Bznad7TWhFEY4LOIwsPlH2RhduxselnuY/s400/IMG_1479+ilmenite+003.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This is a large specimen of staurolite in feldspar from Litchfield, Connecticut<br />
Make an offer more then $150</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQKZR_f_j-2mVh1degNi_J82u3mIPd65i3sVJ835n7j3UAhXJyNgH-gNYJePYHdFvOPSnsA1BoFsiFRrhVBbgfZZ00s6xBBC5mviEdXPpG1SCIvV_dq6RbDt0A6lpojUK0gsV0sDxH_DM/s1600/Schorl+wisps+in+quartz.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQKZR_f_j-2mVh1degNi_J82u3mIPd65i3sVJ835n7j3UAhXJyNgH-gNYJePYHdFvOPSnsA1BoFsiFRrhVBbgfZZ00s6xBBC5mviEdXPpG1SCIvV_dq6RbDt0A6lpojUK0gsV0sDxH_DM/s400/Schorl+wisps+in+quartz.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Schorl wisps in quartz from the Whodunit Mine in Litchfield, CT<br />Price $25.00</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgZBc_D5It3uqAEvGaNef3ZE5FZ47jZcoqRqXWe7deFG1cec6OVhs4WbJVhDL0Xxo5CSL8LykOHlv7P4ig45ZfXugKSlo645hn5nzsnwcX4nedQIl1eBLHg8yTBE0qtKbpPG1QYQTW_f4/s1600/Goethite+from+an+alluvial+deposit+in+Salisbury,+CT.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgZBc_D5It3uqAEvGaNef3ZE5FZ47jZcoqRqXWe7deFG1cec6OVhs4WbJVhDL0Xxo5CSL8LykOHlv7P4ig45ZfXugKSlo645hn5nzsnwcX4nedQIl1eBLHg8yTBE0qtKbpPG1QYQTW_f4/s400/Goethite+from+an+alluvial+deposit+in+Salisbury,+CT.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Goethits pebble from an alluvial deposit in Salisbury, CT<br />Price $12,00</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPNVTWrLly0Oyt20Cwqc3x3uq0PE9fLe24_Ublw3VxMPwdwmQqMYSb_JkUCaKu1vrYLSmhlZ7CWjhPQAEqxrgsj4aFO8nSW4lNj4i_Z4fWpl1tUcCAdrWypnDRfhAAUWCcaKArwJNoZWo/s1600/Stepped+layers+of+platey+ilmenite+in+feldspar+from+the+Whodunit+Mine+in+Litchfield+CT.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPNVTWrLly0Oyt20Cwqc3x3uq0PE9fLe24_Ublw3VxMPwdwmQqMYSb_JkUCaKu1vrYLSmhlZ7CWjhPQAEqxrgsj4aFO8nSW4lNj4i_Z4fWpl1tUcCAdrWypnDRfhAAUWCcaKArwJNoZWo/s400/Stepped+layers+of+platey+ilmenite+in+feldspar+from+the+Whodunit+Mine+in+Litchfield+CT.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Stepped layers of ilmenite is feldspar from the Whodunit Mine in Litchfield, CT<br />Price $25.00</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgM9PlAOIj8uzkG8MdYEg8BWC10n5jZMa7dxQSLV9mVxT7If4HbingK7KaoP_tL7alt15CjC0KCfSXk-6BWJZJhJu1rBUVELd-6p5VF1-43FxqNgMiVWMT7lNdWMOs5DrPpOIF0IILDrbc/s1600/Plateey+Ilmenite+is+feldspar+from+the+Whodunit+Mine+in+Litchfield,+CT.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgM9PlAOIj8uzkG8MdYEg8BWC10n5jZMa7dxQSLV9mVxT7If4HbingK7KaoP_tL7alt15CjC0KCfSXk-6BWJZJhJu1rBUVELd-6p5VF1-43FxqNgMiVWMT7lNdWMOs5DrPpOIF0IILDrbc/s400/Plateey+Ilmenite+is+feldspar+from+the+Whodunit+Mine+in+Litchfield,+CT.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Platy ilmenite crystals in feldspar from the Whodunit Mine in Litchfield, CT<br />Price $50.00</td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXyMbPVp7uBN2-QG_5NHUtR4YxUwG7eDH_j3A-EjcSo99tKPNcG7fbKHnk6PL6EGJ9sZ0kNsSgk2pwaiBoJrLDhdtfR038VwCTc1DYDz6PJM0bVJHu0aR6UU5_Uvs28jLSdEHT5XXmMAw/s1600/Copy+of+Sample+Stones+027.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXyMbPVp7uBN2-QG_5NHUtR4YxUwG7eDH_j3A-EjcSo99tKPNcG7fbKHnk6PL6EGJ9sZ0kNsSgk2pwaiBoJrLDhdtfR038VwCTc1DYDz6PJM0bVJHu0aR6UU5_Uvs28jLSdEHT5XXmMAw/s400/Copy+of+Sample+Stones+027.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This is a sample of kyanite from our locality in Litchfield, Connecticut. This is a large specimen as can be seen by the quarter coin used to illustrate its size. This specimen is truly spectacular with a mere photograph failing to do it justice.<br />
Price $50<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZW0UdI9DMf0_qrf5dz_G7iladiyfIrwUEiPNcxRqlqdOTafKD8MzvezNxaz5bbaGtnkI5pPq_A_MIp9qt1ZNnXXRmUF0eOm5faGoMUGBW6f_FDoXRv552s0dXzNtswC-FDvK0eXSqQXs/s1600/blue+kyanite+in+smoky+quartz.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZW0UdI9DMf0_qrf5dz_G7iladiyfIrwUEiPNcxRqlqdOTafKD8MzvezNxaz5bbaGtnkI5pPq_A_MIp9qt1ZNnXXRmUF0eOm5faGoMUGBW6f_FDoXRv552s0dXzNtswC-FDvK0eXSqQXs/s400/blue+kyanite+in+smoky+quartz.jpg" width="400" /></a></div>
Blue kyanite in smoky quartz from the Whodunit Mine in Litchfield, CT<br />
Price $45.00<br />
<br />
<div style="text-align: left;">
<span style="font-size: small;">About the Whodunit Mine we still don't know what they were mining except it is in a highly mineralised zone that contains many mineral specimens of all sizes and old artifacts. </span></div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
<span style="font-size: small;">We will display more specimens that are for sale as they are prepared and photographed.</span><br />
<span style="font-size: small;"><br /></span><br />
<span style="font-size: small;"><br /></span></div>
<div style="text-align: left;">
<br /></div>
</td></tr>
</tbody></table>
<span style="font-size: large;">For further information about these specimens please contact us at <a href="mailto:geotekllc@gmail.com">geotekllc@gmail.com</a></span><br />
<br />
<br />
<br />
<br /></div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com2tag:blogger.com,1999:blog-3427371516505437050.post-36926545201039752162012-03-10T15:36:00.001-08:002012-03-10T15:36:52.933-08:00Alabaster the Non-Gemstone<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Alabaster_Bazylika_JG.JPG/800px-Alabaster_Bazylika_JG.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="265" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Alabaster_Bazylika_JG.JPG/800px-Alabaster_Bazylika_JG.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Church walls and gold leaf decorations made from calcitic alabaster in Poland<br />Photo by Beemwej</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
There are two distinct minerals that are called <a href="http://en.wikipedia.org/wiki/Alabaster">alabaster</a>, one of them is
calcium sulfate commonly called <a href="http://en.wikipedia.org/wiki/Gypsum">gypsum</a>
or anhydrite. The other is a variety of
calcium carbonate that is commonly known as <a href="http://en.wikipedia.org/wiki/Limestone">limestone</a> or marble. Of these two the former is the alabaster of
today, and the latter is the alabaster of the ancients. Both of these materials are easy to work
with, and have an attractive appearance making them favorites for small
carvings and other works of art. </div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/a/aa/Alabastro1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="312" src="http://upload.wikimedia.org/wikipedia/commons/a/aa/Alabastro1.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The formation of alabaster explained in Italian<br />by Miguel</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Since we've already established that there are two different
types of alabaster the best way to distinguish between them is by their
relative hardness. The first type that is composed of gypsum is so soft you can
scratch it would your fingernail because I have a <a href="http://geology.about.com/od/scales/a/mohsscale.htm">Mohs hardness</a> of
1.5 to 2. The calcite variety of alabaster is too hard to be scratched in this
way having a Mohs hardness of 3 although you can scratch it with a knife blade.
Because it is a carbonate it will effervesce when a drop of <a href="http://www.newworldencyclopedia.org/entry/Hydrochloric_acid">hydrochloric
acid</a> is placed on its surface. When the gypsum type of alabaster has a drop
of mass placed on virtually nothing happens.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/7/72/Flickr_-_DavidDennisPhotos.com_-_Alabaster_Salesman_in_Luxor.jpg/800px-Flickr_-_DavidDennisPhotos.com_-_Alabaster_Salesman_in_Luxor.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="285" src="http://upload.wikimedia.org/wikipedia/commons/thumb/7/72/Flickr_-_DavidDennisPhotos.com_-_Alabaster_Salesman_in_Luxor.jpg/800px-Flickr_-_DavidDennisPhotos.com_-_Alabaster_Salesman_in_Luxor.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An alabaster lamp<br />Photo by David Dennis</td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
Although alabaster can come in many different colors most
people think of it as white, so much so that it has entered the language as a
metonym for weight objects. In this sense it is often used to describe
“alabaster skin” that means very light and quite transparent that is derived
from the use of alabaster in building tombs.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Although alabaster is essentially too soft for use as a
gemstone it often finds uses as a decorative stone for making different kinds
of statuary and other objects de art. A very common use today is making the
basis for electric lamps.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Alabaster.jpg/800px-Alabaster.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="270" src="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Alabaster.jpg/800px-Alabaster.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A piece of raw alabaster<br />Photo by Ra'ike</td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
The word alabaster itself is derived from middle English as
well as several other languages including Greek. The word was used to identify a
type of vase made of alabaster. There is a certain amount of evidence that the
word can be traced all the way back to ancient <st1:country-region><st1:place>Egypt</st1:place></st1:country-region>
where it was named after the town <a href="http://www.britannica.com/EBchecked/topic/12011/alabastron">Alabastron</a>
where it was commonly found. It was Alabastron where it was originally
quarried, however the name of the mineral is still obscure.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The so-called “Oriental” alabaster was highly esteemed by
sea ancients for making such items as small perfume bottles small point that
basis that were called alabastra. This thing has also been suggested as a
possible source of the mineral name. The craftsmen of this stone in ancient <st1:country-region><st1:place>Egypt</st1:place></st1:country-region>
often used alabaster for use in candlestick chart and various other sacred and
sepulchral objects. In the Sir John Soane’s Museum in <st1:city><st1:place>London</st1:place></st1:city>
is a sarcophagus that was carved from a single block of translucent calcite
alabaster that was mined Alabastron.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/7/7a/Alabastro_z05.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://upload.wikimedia.org/wikipedia/commons/7/7a/Alabastro_z05.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An alabaster carver at work.<br />Photo by Zyance</td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
Both types of alabaster are essentially <a href="http://en.wikipedia.org/wiki/Evaporite">evaporative minerals</a> in the
case of the gypsum variety it is the mineral that evaporates from seawater
before salt, In the case of the calcitic
variety is has its origin from the evaporation of lime water that has reached
saturation. Any further water loss
causes the lime to come out of solution where it is deposited. A lot of this
type of alabaster is found on the walls and floor of caves where it also forms
the formations we call stalactites and stalagmites. </div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Louvres-antiquites-egyptiennes-img_2757.jpg/800px-Louvres-antiquites-egyptiennes-img_2757.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Louvres-antiquites-egyptiennes-img_2757.jpg/800px-Louvres-antiquites-egyptiennes-img_2757.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ancient alabaster vases<br />Louvre Museum, Paris, France</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Although most people think of alabaster as a white mineral
it is also found in many other colors particularly when it is stained by
mineral salts. Iron is the most common of these although copper and manganese
also one of their own suite of colors to the stone. If you cut large blocks of
this material into thin sheets they can be used as translucent windows such as
those found in the <a href="http://www.library.yale.edu/beinecke/">Beineke
Library</a> of Rare Manuscripts and Books at <a href="http://www.yale.edu/">Yale
University</a>. Throughout the ages how a master has been used to make many
beautiful objects and will continue to do so into the future.</div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com1tag:blogger.com,1999:blog-3427371516505437050.post-57922416087991915112012-03-08T13:39:00.001-08:002012-03-08T13:39:39.490-08:00Beryl the Genstone of Many Colors<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/7/78/Berillo.jpg/800px-Berillo.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://upload.wikimedia.org/wikipedia/commons/thumb/7/78/Berillo.jpg/800px-Berillo.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Beryl crystals from Pakistan var. aquamarine<br />Photo by Gia Cassa</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
As a mineral <a href="http://www.mindat.org/min-819.html">beryl</a>
is beryllium aluminum <a href="http://www.galleries.com/minerals/silicate/cyclosil.htm">cyclosilicate</a>
possessing the chemical formula Be<sub>3</sub>Al<sub>2</sub>(SiO<sub>3</sub>)<sub>6. </sub>As a gem it comes in many colors
although pure beryl is colorless of the variety <a href="http://www.mindat.org/min-7555.html">goshenite</a> named after the town
of <st1:city><st1:place>Goshen</st1:place></st1:city> in the central Berkshires
of Massachusetts its type locality. It
is tinted by different colors causing it to be colored blue, green, red, yellow
and white. This is a mineral that is
usually found in pegmatites although it is often found in biotite schists and
in intruded limestone. A rare occurrence
is found in <st1:state><st1:place>Utah</st1:place></st1:state> called <a href="http://www.sparklingsplendor.com/bixbite.php">bixbite</a> that has been
colored red by manganese as an impurity.
Other gems in this family include <a href="http://en.wikipedia.org/wiki/Aquamarine">aquamarine</a>, <a href="http://www.gemstone.org/index.php?option=com_content&view=article&id=84:sapphire&catid=1:gem-by-gem&Itemid=14">emerald</a>,
<a href="http://www.jjkent.com/articles/emeralds-green-beryl.htm">green beryl</a>,
<a href="http://gemologyonline.com/heliodor.html">heliodor</a> and <a href="http://www.gemstone.org/index.php?option=com_content&view=article&id=131:sapphire&catid=1:gem-by-gem&Itemid=14">morganite</a>. <o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/B%C3%A9ryl_var._%C3%A9meraude_sur_gangue_(Muzo_Mine_Boyaca_-_Colombie)_15.jpg/800px-B%C3%A9ryl_var._%C3%A9meraude_sur_gangue_(Muzo_Mine_Boyaca_-_Colombie)_15.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="257" src="http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/B%C3%A9ryl_var._%C3%A9meraude_sur_gangue_(Muzo_Mine_Boyaca_-_Colombie)_15.jpg/800px-B%C3%A9ryl_var._%C3%A9meraude_sur_gangue_(Muzo_Mine_Boyaca_-_Colombie)_15.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An emerald crystal from Colombia<br />Photo by Gery Parent</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Aquamarine is the color of sea water a bluish green with
green beryl as a sub-order of aquamarine.
Emerald of course is bright green that is usually found in heavily
intruded limestone although some occurrences are in biotite schist. Heliodor is the yellow variety of beryl that
is sometimes galled “golden beryl.” Morganite
is sometimes found associated with both aquamarine and <a href="http://www.addmorecolortoyourlife.com/gemstones/golden-beryl.asp">golden
beryl</a>, bit is differentiated by its pink color. Red beryl is also called bixbite or red
emerald because of its red coloration.
Of all the beryl’s bixbite is the rarest, but only occurs in small
crystals allowing gems cut from it to be lass then 5 carets in weight,</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/6/6d/Beryl_golden_beryl_rough_XH.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="343" src="http://upload.wikimedia.org/wikipedia/commons/6/6d/Beryl_golden_beryl_rough_XH.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Golden beryl or heliodor<br />unknown</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Beryl aside from its use as a gem is also the ore of <a href="http://www.newworldencyclopedia.org/entry/Beryllium">beryllium</a> where
it occurs in granitic pegmatites. One
such crystal was a giant that occurred in the Bumpus Quarry in <st1:place><st1:city>Albany</st1:city>,
<st1:state>Maine</st1:state></st1:place> that was about 5.5 meters long by 1.2
meters in diameter that weighed around 18 metric tons. The largest crystal of any kind of mineral was
found in <st1:country-region><st1:place>Madagascar</st1:place></st1:country-region>
is a beryl crystal that was 18 meters long by 3.5 meters in diameter. That is the size as the boiler on a steam
locomotive.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/3/30/Beryl-rb1b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/3/30/Beryl-rb1b.jpg" width="387" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A crystal of red beryl var. bixbite from Utah<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Beryl is found on all the continents wherever crystalline
igneous or metamorphic rocks are found.
The gems are found in the core of pegmatites where at times <a href="http://en.wikipedia.org/wiki/Double_Terminated_Crystal">terminated
crystals</a> are found growing into cavities or vugs in the rock. Some beryl like the emeralds found in
Columbia are found in a peculiar black limestone that has been intruded with
granite that contain in addition to the beryl an abundant amount of pyrite that
certainly predates the formation of the emerald crystals.. Beryl is also found
associated with biotite schist. Many of
the emeralds found in the Ural Mountains of Russia are this type of
deposit. The emeralds found at the <a href="http://weewillystine.net/ttt/060529BlueRidge03.shtml">Crabtree Corners</a>
deposit in <st1:state><st1:place>North Carolina</st1:place></st1:state> are
also an example of this kind of deposit.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/d/db/Beryl-Albite-Quartz-278464.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="345" src="http://upload.wikimedia.org/wikipedia/commons/d/db/Beryl-Albite-Quartz-278464.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A crystal of morganite on albite and quartz.<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
One of the most important deposits of aquamarine in the
United States is found in the Maryall district of New Milford, Connecticut
where they occur in a large pegmatite that that was originally mined for
feldspar and mica. This mine has
produced some fine specimens of both aquamarine and heliodor beryl including a
44 carat heart on display in the American Museum of Natural History in New York
City. It is also known to produce many
other minerals especially large garnets and uranium minerals. </div>
<div class="MsoNormal">
<br /></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com1tag:blogger.com,1999:blog-3427371516505437050.post-25605760724821992692012-03-08T08:53:00.001-08:002012-03-08T08:53:31.364-08:00Amblygonite one of the Gemological Garbage Cans<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Amblygonit_-_Montebras,_Frankreich.jpg/668px-Amblygonit_-_Montebras,_Frankreich.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="357" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Amblygonit_-_Montebras,_Frankreich.jpg/668px-Amblygonit_-_Montebras,_Frankreich.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">It is easy to see how amblygonite is often mistaken for other minerals this specimen mimics milky quartz<br />Photo by Ra'ike<br /></td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
As a mineral <a href="http://www.mindat.org/min-189.html">amblygonite</a>
is classified as a <a href="http://dictionary.reference.com/browse/fluorophosphate">fluorophosphate</a>
with a chemical formula of (Li, Na)AlPO<sub>4</sub>(F, OH) that is composed of
sodium, lithium, aluminum, phosphate, fluoride and hydroxide. This is a mineral
occurs in <a href="http://www.newworldencyclopedia.org/entry/Pegmatite">pegmatite</a>
deposits were this easily mistaken for albite or other feldspars. It is readily
distinguished by its density, cleavage and <a href="http://chemistry.about.com/od/analyticalchemistry/a/flametest.htm">flame
test</a> for lithium. Amblygonite forms a <a href="http://www.enotes.com/solid-solution-series-reference/solid-solution-series">solid
solution series</a> with <a href="http://webmineral.com/data/Montebrasite.shtml">montebrasite</a>
that is the low fluorine member of the series.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Amblygonit_facettiert_-_Minas_Gerais,_Brasilien.jpg/750px-Amblygonit_facettiert_-_Minas_Gerais,_Brasilien.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="http://upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Amblygonit_facettiert_-_Minas_Gerais,_Brasilien.jpg/750px-Amblygonit_facettiert_-_Minas_Gerais,_Brasilien.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Faceted amblygonite from Brazil.<br />Photo by Ra'ike</td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
This is a mineral found in <a href="http://jaristoteles.com/geologie/bscmsc/MSc%20thesis%20-%20Ut%25C3%25B6%20LCT-pegmatites%20PDF.pdf">LCT
type pegmatites</a>, high-temperature tin veins and greisens where it is found
with spodumene, apatite, lepidolite, tourmaline and other lithium bearing
minerals. It is often been used as an ore of lithium The chief commercial
sources have been the deposits in <st1:state><st1:place>California</st1:place></st1:state>
and <st1:country-region><st1:place>France</st1:place></st1:country-region>
where the mineral contains about 10% lithium.
</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/2/2c/Amblygonite-mun05-36a.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/2/2c/Amblygonite-mun05-36a.jpg" width="317" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A single crystal of faceting grade amblygonite.<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The mineral amblygonite was originally discovered in Saxony,
Germany by <a href="http://en.wikipedia.org/wiki/August_Breithaupt">August
Breithaupt</a> in 1817 and named by him from the Greek words amblus (blunt) and
gouia (blunt) because there is an obtuse angle between its cleavages. Later the same mineral was found at <st1:place><st1:city>Montebras</st1:city>,
<st1:country-region>France</st1:country-region></st1:place> and <st1:place><st1:city>Hebron</st1:city>,
<st1:state>Maine</st1:state></st1:place>. Because there are slight optical
differences in amblygonite found at these differing localities they are also
called montebrasite and hebronite after the localities where it has been
found. The mineral is also found in
large quantities in Pala in <st1:place><st1:city>San Diego County</st1:city>, <st1:state>California</st1:state></st1:place>
as well in the Black Hills of South Dakota.
To date the largest single crystal of amblygonite measured 7.62 x 2.44 x
1.83 meters that weighed about 102 tons.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Amblygonite-Montebrasite-rw17b.jpg/666px-Amblygonite-Montebrasite-rw17b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="358" src="http://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Amblygonite-Montebrasite-rw17b.jpg/666px-Amblygonite-Montebrasite-rw17b.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Amblygonite variety Montebrasite<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
When its transparent amblygonite is faceted into gemstones
where it is set into jewelry, however because it is prone to breakage and
abrasion as well as displaying hardness problems as well as toughness it is
rarely mounted into jewelry. This stone
when it is cut often finds its way into collections as unmounted stones. The
principle sources of this gemstone are <st1:country-region><st1:place>Brazil</st1:place></st1:country-region>
and the <st1:country-region><st1:place>United States</st1:place></st1:country-region>
however other countries have also produced faceting grade amblygonite such as <st1:country-region><st1:place>Australia</st1:place></st1:country-region>,
<st1:country-region><st1:place>France</st1:place></st1:country-region>, <st1:country-region><st1:place>Germany</st1:place></st1:country-region>,
<st1:country-region><st1:place>Namibia</st1:place></st1:country-region>, <st1:country-region><st1:place>Norway</st1:place></st1:country-region>
and <st1:country-region><st1:place>Spain</st1:place></st1:country-region>. Most of the gem quality amblygonite crystals
that have a yellowish caste are found in pegmatite cavities. <o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com2tag:blogger.com,1999:blog-3427371516505437050.post-73123211818035225102012-03-03T19:32:00.001-08:002012-03-03T19:32:57.719-08:00Benitoite the One of a Kind Gemstone<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<div class="MsoNormal">
</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/4/4b/Benitoite-Neptunite-20489.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="335" src="http://upload.wikimedia.org/wikipedia/commons/4/4b/Benitoite-Neptunite-20489.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Benitoite in a matrix of neptunite from San Benito County, California.<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://www.benitoitemine.com/benitoite/benitoit.shtml">Benitoite</a> is a
one-of-a-kind gem since it is only found in one place in <st1:state><st1:place>California</st1:place></st1:state>;
it is also the state gemstone of <st1:state><st1:place>California</st1:place></st1:state>
as of 1985. The stone itself is a rare
variety of barium-titanium silicate found in <a href="http://sbgeo.org.br/pub_sbg/rbg/vol25_down/2503/2503173.pdf">hydrothermally
altered</a> serpentine. Benitoite reacts under shortwave ultraviolet light
fluorescing light blue in color.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
As a mineral benitoite was described in 1907 by George D.
Louderback who named it benitoite because it was found near the headwaters of
the San Benito River of San Benito County, <st1:state><st1:place>California</st1:place></st1:state>.
The stone was one of the first if not the first mineral to be studied under
x-ray diffraction.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/a/af/Benitoit_i_Joaquinit_-_Gem_mine_,_near_Clear_Creek,_San_Benito_Co.,_California,_USA.jpg/800px-Benitoit_i_Joaquinit_-_Gem_mine_,_near_Clear_Creek,_San_Benito_Co.,_California,_USA.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="266" src="http://upload.wikimedia.org/wikipedia/commons/thumb/a/af/Benitoit_i_Joaquinit_-_Gem_mine_,_near_Clear_Creek,_San_Benito_Co.,_California,_USA.jpg/800px-Benitoit_i_Joaquinit_-_Gem_mine_,_near_Clear_Creek,_San_Benito_Co.,_California,_USA.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A single crystal of benitoite in matrix.<br />Photo by Lech Darski</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This stone is usually found an unusual set of minerals
including the minerals that make up its host rock. The associated minerals
usually include naturolite, neptunite, joaquinite, serpentine and albite.
Benitoite is very rare mineral that is only found that it few locations among
them are places in <st1:place><st1:city>San Benito County</st1:city>, <st1:state>California</st1:state></st1:place>.
It is also been found in <st1:state><st1:place>Arkansas</st1:place></st1:state>
and <st1:country-region><st1:place>Japan</st1:place></st1:country-region>. It
is usually found in <a href="http://rruff.geo.arizona.edu/doclib/cm/vol20/CM20_41.pdf">glaucophane
schist</a> as inclusions in veins of naturolite. Benitoite mining is allowed for a fee in the
benitoite mine in the <st1:city><st1:place>Clearwater</st1:place></st1:city>
management area in central <st1:state><st1:place>California</st1:place></st1:state>.
Collecting is by appointment only!</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This gemstone is typically colored various shades of blue
although it can also appear as colorless or even have a yellowish caste. Its crystals can vary from transparent to
translucent with visible inclusions with a vitreous luster.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/f/fa/Benitoite-dtn18a.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/f/fa/Benitoite-dtn18a.jpg" width="372" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A single crystal of benitoite with no matrix.<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
When found its crystals are hexagonal; bar 6 m 2 that in
crystal habits include six place dipyramid flattened shapes having a distinct
triangle shape that is often modified by having minor faces. At times it is also found as small grains.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Benitoite has no cleavage and its fracture is irregular. Other distinguishing features are its
hardness ranging from 6 to 6.5 on the Moh’s scale of hardness. Its specific gravity is 3.6 making it denser
then most other minerals making it capable of being separated by gravity
methods such as panning. The mineral
also displays a white streak. </div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/5/55/Benitoite200ppx.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="374" src="http://upload.wikimedia.org/wikipedia/commons/5/55/Benitoite200ppx.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A faceted example of benitoite<br />Photo by Fastily</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This mineral is counted among those that <a href="http://en.wikipedia.org/wiki/Fluorescence">fluoresce</a> under the
influence of ultraviolet light displaying a blue light. Minerals that are associated with benitoite
include serpentine, neptunite, natrolite, joaquinite, sanbornite, taramellite,
albite and fresonite. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Benitoite gems are only found in three mines located in <st1:place><st1:city>San
Benito County</st1:city>, <st1:state>California</st1:state></st1:place> where
good to excellent crystals are found. The
only other occurrences are in Eocene aged sands in southwestern <st1:state><st1:place>Texas</st1:place></st1:state>
along with another few localities in <st1:state><st1:place>California</st1:place></st1:state>. These occurrences are only small grains found
in sand. </div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/B%C3%A9nitoite_sous_U.V._(USA)_.jpg/800px-B%C3%A9nitoite_sous_U.V._(USA)_.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="265" src="http://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/B%C3%A9nitoite_sous_U.V._(USA)_.jpg/800px-B%C3%A9nitoite_sous_U.V._(USA)_.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Benitoite under ultraviolet light.<br />Photo by Parent Gery </td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
If you are searching for this mineral the best field
indicators its crystal habit, the fact that it displays fluorescence in blue,
its distinctive color, the minerals it is associated with and the locality. The fact it is associated with bodies of
serpentine suggests that it might be found in localities that have been
identified as <a href="http://en.wikipedia.org/wiki/Suture_(geology)">suture
zones</a> where geologists feel that serpentine is metamorphosed oceanic crust
that has been caught up in earth movements associated with the collision of two
continental plates,</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<span style="font-family: Verdana; font-size: 13.5pt;"> <o:p></o:p></span></div>
<br />
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com1tag:blogger.com,1999:blog-3427371516505437050.post-72909798990605072412012-03-02T13:03:00.001-08:002012-03-02T13:03:22.140-08:00Azurite Hydrous Copper Carbonate a Blue Gem.<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/6/69/Azurite-117493.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/6/69/Azurite-117493.jpg" width="377" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Botrydoil Azurite from the Apex Mine of Utah.<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://www.mindat.org/mesg-66-115319.html">Azurite</a>
is one of the lesser known copper ores that is produced by the weathering of
copper deposits. The mineral is also known as <a href="http://www.mindat.org/min-4704.html">chessylite</a> named after the
Chessy-les-Mines near the city of <st1:city><st1:place>Lyon</st1:place></st1:city>
in <st1:country-region><st1:place>France</st1:place></st1:country-region>. This
mineral has been known to the ancients and is mentioned in <a href="http://www.livius.org/pi-pm/pliny/pliny_e.html">Pliny the Elder’s</a>,
Natural History. Because of its deep
blue color has also been used as a pigment that is a deep blue color. Azurite
is usually found in the desert where the low humidity causes its cousin <a href="http://www.mindat.org/min-2550.html">malachite</a> to lose water. This is where it is often found in the
company of its cousin malachite. Both
minerals are essentially the same copper carbonate except azurite contains more
water in its crystals. Over time this
water will evaporate causing the azurite to change to malachite.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Typically azurite crystals are <a href="http://en.wikipedia.org/wiki/Monoclinic">monoclinic</a> that when they
are large enough to be seen will appear is dark blue <a href="http://www.galleries.com/minerals/property/habits.htm">prismatic crystals</a>.
In nature azurite crystals are massive to nodular with some of them forming
stalactitic masses. Any specimen of azurite over time will lighten in color as
its surface retrogrades in the malachite. The mineral is soft with a Mohs
hardness of 3.5 to 4. It displays a <a href="http://en.wikipedia.org/wiki/Specific_gravity">specific gravity</a>
ranging from 3.77 to 3.89. The mineral azurite is destroyed by the application
of heat losing both carbon dioxide and water forming a type of black powdery
copper oxide. A drop of acid placed on the specimen will cause it to <a href="http://www.bing.com/Dictionary/search?q=define+effervesce&qpvt=effervesce&FORM=DTPDIA">effervesce</a>
like any other carbonate.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/0/09/Azurite-18531.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://upload.wikimedia.org/wikipedia/commons/0/09/Azurite-18531.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Azurite and malachite<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Some of the earliest uses of azurite are a blue pigment in artist’s
paints. In this use it was finely ground, and then <a href="http://www.thefreedictionary.com/mulled">mulled</a> with linseed oil and
turpentine. The mineral is capable of producing many different shades of blue
depending upon the fineness to which it is ground. When it is mixed with oil,
as in oil paints it turns slightly green. On the other hand if it is mixed with
egg yolk it turns a gray green. In older paintings the azurite has turned into
malachite displaying a greenish color. Many times what was azurite was
mislabeled as <a href="http://www.gemstone.org/index.php?option=com_content&view=article&id=117:sapphire&catid=1:gem-by-gem&Itemid=14">lapis
lazuli</a> that in times past was a name that was applied to many other blue
pigments. True lapis lazuli that was used as another blue pigment came
primarily from <st1:country-region><st1:place>Afghanistan</st1:place></st1:country-region>
during the Middle Ages. Azurite was a common mineral found in <st1:place>Europe</st1:place>
in the same timeframe.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Lapis_lazuli_block.jpg/337px-Lapis_lazuli_block.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Lapis_lazuli_block.jpg/337px-Lapis_lazuli_block.jpg" width="225" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Lapis Lazuli, notice the difference in color from azurite.</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
There were sizable deposits of azurite that were mined near <st1:place><st1:city>Lyons</st1:city>,
<st1:country-region>France</st1:country-region></st1:place> during the Middle
Ages. Azurite was also mined during the 12th century in <st1:place>Saxony</st1:place>
and the various silver mines that were located there.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
If azurite is heated it turns black whereas the more
expensive natural ultramarine remains blue when it is heated. If the mineral is
gently heated it produces a deep blue pigment that is often used by the Japanese
in some of their painting techniques.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/9/95/Azurite-Malachite-117944.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="386" src="http://upload.wikimedia.org/wikipedia/commons/9/95/Azurite-Malachite-117944.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Azurute surrounded by malachite.<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Occasionally azurite finds uses beads and other types of jewelry;
it is also used as a decorative stone. The thing that keeps it from being used
more commonly as a gemstone is its softness and the fact that it weathers
easily reverting back to malachite.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
. </div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com1tag:blogger.com,1999:blog-3427371516505437050.post-87852424298775912572012-02-28T15:17:00.001-08:002012-02-28T15:17:08.162-08:00The Emerald Green Garnet Andradite<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/d/d1/Andradite-216056.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="311" src="http://upload.wikimedia.org/wikipedia/commons/d/d1/Andradite-216056.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Demantoid an emerald green variety of andradite garnet on a matrix of serpentine,<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://www.mindat.org/min-223.html">Andradite</a>
is another species longing for the garnet family that is classified as a <a href="http://www.britannica.com/EBchecked/topic/409771/nesosilicate">nesonsilicate</a>
with a formula approximating Ca<sub>3</sub>Fe<sub>2</sub>Si<sub>3</sub>O<sub>12</sub>. This family of <a href="http://minerals.usgs.gov/minerals/pubs/commodity/gemstones/sp14-95/garnet.html">garnets</a>
includes three different varieties they come in various colors. There is one
variety where titanium ions substitute in the formula producing a black stone
that in the gem trade is called <a href="http://www.mindat.org/min-7443.html">melanite</a>,
or is sometimes referred to as titanian andradite. The second stone in this
group is referred to as the <a href="http://www.gemstone.org/index.php?option=com_content&view=article&id=108:sapphire&catid=1:gem-by-gem&Itemid=14">demantoid</a>
garnet that is found ophiolite deposits where it is associated with chromium.
The stones are often the vivid green in color that occur in small crystals
rarely over one carat in size. Because of their rarity they are often worth
more than $1000 per carat in the <a href="http://www.gia.edu/">http://www.gia.edu/</a>
world. The third type of stone in this family is called Topazolite that is
yellowish green in color and is sometimes found in a high enough quality so
they can be cut into faceted gems.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/4/46/Andradite-120511.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="393" src="http://upload.wikimedia.org/wikipedia/commons/4/46/Andradite-120511.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Melanite garnet crystals<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This garnet occurs in <a href="http://www.science.smith.edu/geosciences/skarn/aboutskarn.html">skarns</a>
in impure limestone that has been intruded by igneous rock. Sometimes it is
also found in calcium rich igneous rocks. Probably the most common place to
find andradite is in a rock called serpentine that also produces asbestos.
Andradite garnets have been found in the asbestos mines around <st1:place><st1:city>Thetford
Mines</st1:city>, <st1:state>Quebec</st1:state></st1:place> in small
crystals. <a href="http://www.cst.cmich.edu/users/dietr1rv/serpentine.htm">Serpentine</a>
is thought by geologists to be metamorphosed oceanic crust that was caught up
in a mountain building event where some of the ocean crust was incorporated
into a continental landmass.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/a/a7/Andradite-66648.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="345" src="http://upload.wikimedia.org/wikipedia/commons/a/a7/Andradite-66648.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Topazolite crystals<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
There are several other minerals that are commonly
associated with andradite including this vesuvianite, chlorite, epidote,
spinel, calcite, dolomite and magnetite. One of the varieties of andradite is
often found near iron mines where the over is magnetite. It is found as
braunite on the rock dumps at the old Tillie Foster iron mine in <st1:place><st1:city>Brewster</st1:city>,
<st1:state>New York</st1:state></st1:place>.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/c/c9/Andradite-165273.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/c/c9/Andradite-165273.jpg" width="390" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A faceting grade crystal of demantoid. Sometimes faceted gems cut from this stone can sell for well over $1,000 per carat. Most of these stones are small rare;y affording faceted gems weighing much more then a carat.<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
Andradite is found in <st1:country-region><st1:place>Italy</st1:place></st1:country-region>
around the area of <a href="http://ancienthistory.about.com/od/italialatiumitaly/g/Vesuvius.htm">Mt.
Vesuvius</a> and other volcanic areas that are underlain by limestone. It is also found in <st1:country-region><st1:place>Russia</st1:place></st1:country-region>
in the Urals. In the <st1:country-region><st1:place>United
States</st1:place></st1:country-region> this stone is found in <st1:state><st1:place>Arizona</st1:place></st1:state>
and <st1:state><st1:place>California</st1:place></st1:state>. On the East Coast several occurrences are in
the <st1:place><st1:city>Danbury</st1:city>, <st1:state>Connecticut</st1:state></st1:place>
area where andradite occurs in limestone deposits along Rt. 7 where the
limestone is in close proximity to intrusions of granite where it is associated
with danburite and idocrase. This is a
mineral that should be found in serpentine or contact altered limestone
anywhere they are found.</div>
<div class="MsoNormal">
<br /></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com1tag:blogger.com,1999:blog-3427371516505437050.post-87967661666198999672012-02-28T06:29:00.001-08:002012-02-28T06:29:10.260-08:00Amber is Fossilized Tree Resin<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Spider_in_amber_(1).jpg/740px-Spider_in_amber_(1).jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="323" src="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Spider_in_amber_(1).jpg/740px-Spider_in_amber_(1).jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Amber with a spider inclusion that came from the Baltic Sea area.<br />Photo by Elizabeth from Holland </td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Although not a gemstone in the proper sense <a href="http://en.wikipedia.org/wiki/Amber">Amber</a> in reality is fossilized
tree <a href="http://en.wikipedia.org/wiki/Resin">resin</a> that is several
million years old. It is one of the oldest gems known to man where it is
mentioned in the Bible and also by <a href="http://www.livius.org/pi-pm/pliny/pliny_e.html">Pliny the Elder</a>, who
lived during the <st1:place>Roman Empire</st1:place>. Pliny was killed by the
eruption of Vesuvius on August 24, 79 A.D.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Although amber is found in many parts of the world its
earliest occurrence was when Amber was found around the <st1:place>Baltic Sea</st1:place>
where it is still mined to this day.
Other places in the world where amber is found include the <st1:country-region><st1:place>United
States</st1:place></st1:country-region>, the <st1:country-region><st1:place>Dominican
Republic</st1:place></st1:country-region>, <st1:country-region><st1:place>New
Zealand</st1:place></st1:country-region> and <st1:country-region><st1:place>Indonesia</st1:place></st1:country-region>. In truth amber enjoys a worldwide occurrence.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/e/e9/Ambre_bleu_dominicain_21207.jpg/800px-Ambre_bleu_dominicain_21207.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="286" src="http://upload.wikimedia.org/wikipedia/commons/thumb/e/e9/Ambre_bleu_dominicain_21207.jpg/800px-Ambre_bleu_dominicain_21207.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Blue amber from the Dominican Republic<br />Photo by Vassil </td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
Mankind has admired amber for thousands of years where he
appreciated its color and natural beauty since <a href="http://www.worldmuseumofman.org/neolithic.php">Neolithic times</a>. Amber is still used as an ingredient in perfumes;
it has also been used as a healing agent in <a href="http://en.wikipedia.org/wiki/Folk_medicine">folk medicine</a>. Amber however finds its major use in Jewelry.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/4/41/Amber.pendants.800pix.050203.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="298" src="http://upload.wikimedia.org/wikipedia/commons/4/41/Amber.pendants.800pix.050203.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Amber pendents with inclusions<br />Photo by Adrian Pingstone</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Geologically there are five recognized classes of amber that
are defined according to their chemical composition. Amber comes from a sticky tree resin that
over time hardens by the loss of volatile chemicals it can contain various
animal and plant remains as inclusions.
Some amber occurs in coal seams that are called <a href="file:///C:/Documents%20and%20Settings/TEMP/My%20Documents/BLOGS/GEMSTONES/COLORED%20GEMS/resinite">resinite</a>. The term ambrite is specifically applied to
amber that found in the coal seams of <st1:country-region><st1:place>New
Zealand</st1:place></st1:country-region>.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/3/30/Amber_Bernstein_many_stones.jpg/800px-Amber_Bernstein_many_stones.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="265" src="http://upload.wikimedia.org/wikipedia/commons/thumb/3/30/Amber_Bernstein_many_stones.jpg/800px-Amber_Bernstein_many_stones.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Amber rough from the Baltic Sea where it is washed up after heavy storms.<br />This amber is waiting to be processed.<br />Photo by Lanzi</td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
One of the rarest members of the amber family is found in
the <st1:country-region><st1:place>Dominican Republic</st1:place></st1:country-region>
that is blue and flouresis under ultraviolet light. Amber is found in several parts of the
eastern <st1:country-region><st1:place>United States</st1:place></st1:country-region>
most notably on <st1:place>Martha’s Vineyard</st1:place> where it is found on
Gayhead. The stone is also found in the <a href="http://dictionary.reference.com/browse/marl">marl</a> deposits of <st1:state><st1:place>New
Jersey</st1:place></st1:state>. </div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com1tag:blogger.com,1999:blog-3427371516505437050.post-52309484922300337282012-02-27T08:03:00.001-08:002012-02-27T08:03:32.404-08:00Ametrine the Astounding Bicolored Stone<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/4/4c/Ametrine_cut.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://upload.wikimedia.org/wikipedia/commons/4/4c/Ametrine_cut.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A faceted example of ametrine<br />Photo by De Wela49</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://en.wikipedia.org/wiki/Ametrine">Ametrine</a>
is a variety of colored quartz where one end of the crystal is amethyst colored
and the other end is citrine colored. Most of these stones are found in <st1:country-region><st1:place>Bolivia</st1:place></st1:country-region>
and are often marketed under the name <a href="http://www.mindat.org/min-4802.html">bolivinite</a>. Because they are
fairly abundant they are not considered to be an expensive gem. Many of these
stones today are actually <a href="http://en.wikipedia.org/wiki/Synthetic">synthetics</a>
made in <st1:country-region><st1:place>Russia</st1:place></st1:country-region>.
</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
In 1994 a Russian chemist perfected a method to make
multicolored quartz crystals in a pressurized vessel. These stones are later
subjected to radiation that brings out the typical Ametrine colors. It is easy
to detect these stones because in nature neither yellow-green nor gold-blue
exists. In nature but artificial ametrine can also be created by treating an
amethyst crystal on one end with heat. Since quartz is a poor conductor of heat
only one end of the crystal that has been heated will change color.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Ametrin_from_Bolivia.jpg/800px-Ametrin_from_Bolivia.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="260" src="http://upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Ametrin_from_Bolivia.jpg/800px-Ametrin_from_Bolivia.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An example of ametrine from Bolivia.<br />Photo by Ra'ike </td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
The most probable cause of a bi-colored amethyst crystal is
by differential heat that is applied to one end of the crystal; in the case of
Bolivianite causing a temperature differential across the length of the crystal
will create a bi-colored stone.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Most of the Ametrine enters into trade comes from a single mine
in <st1:country-region><st1:place>Bolivia</st1:place></st1:country-region>
although there are some other places that produce the same gem notably <st1:country-region><st1:place>Brazil</st1:place></st1:country-region>
and <st1:country-region><st1:place>India</st1:place></st1:country-region>.
There are several legends concerning the Bolivian mine the most prevalent being
the one about a Spanish Conquistador who presented them to the Spanish Queen as
a present after he had learned about the <a href="http://www.mindat.org/loc-11804.html">Anahi mine</a> where they were
produced as a dowry present to Mary by an Indian princess named Anahi from the <a href="http://en.wikipedia.org/wiki/Ayoreos">Ayereos</a> tribe.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/a/a4/Quartz-177270.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/a/a4/Quartz-177270.jpg" width="241" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An ametrine crystal also from Bolivia<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Typically Ametrine is faceted into a rectangular shape with
a 50-50 combination of amethyst and citrine showing its bicolor nature. There
are times when there is a checkerboard pattern of facets that is added to the
top of the stone to increase the natural light reflection. This stone can also
be cut in such a way as to blend the two colors creating a mixture of yellow,
purple, and peach tones in the stone. Ametrine is also a popular stone among
artistic cutters and carvers that like to play with the various colors creating
landscapes from the stone.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
When buying one of these stones the buyer has to remember
that at a Moh’s hardness of 7 it is not a particularly durable stone that
should not be used in rings that are going to be worn steadily. This tone is
more suitable for broaches and pendants. You can buy this stone in just about
any size or shape but remember the color contrast stands out better in stones
over seven carats in size.</div>
<div class="MsoNormal">
<br /></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com2tag:blogger.com,1999:blog-3427371516505437050.post-81333323365147724632012-02-25T18:10:00.001-08:002012-02-25T18:10:43.452-08:00Amazonite the Green Feldspar Gem<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/c/cf/Microcline-20436.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="342" src="http://upload.wikimedia.org/wikipedia/commons/c/cf/Microcline-20436.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Amazonite a green variety of microcline feldspar.<br />
Photo by Rob Lavinsky</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://en.wikipedia.org/wiki/Amazonite">Amazonite</a>
that is also cold Amazon stone is a green colored variety of microcline a type
of feldspar. It got its name from the <a href="http://en.wikipedia.org/wiki/Amazon_River">Amazon River</a> when certain
green stones were formerly obtained from the land surrounding the river although
it is doubtful that any of this green feldspar occurs anywhere in the Amazon
region.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/1/12/Quartz-Microcline-271346.jpg/390px-Quartz-Microcline-271346.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/12/Quartz-Microcline-271346.jpg/390px-Quartz-Microcline-271346.jpg" width="260" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Amazonite with terminated smoky quartz crystals.<br />
Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Although amazonite is a mineral having a limited occurrence
it was originally obtained from the Miass district in the <a href="http://www.traveljournals.net/explore/russia/map/m4081436/ilmen_mountains.html">Ilman
Mountains</a> about 50 miles southwest of <a href="http://en.wikipedia.org/wiki/Chelyabinsk">Chelyabinsk</a>, <st1:country-region>Russia</st1:country-region>.
It was found here in granitic rocks in small quantities. It can also be found
in the <st1:country-region><st1:place>United States</st1:place></st1:country-region>
as high-quality crystals found in the area of <a href="http://en.wikipedia.org/wiki/Pikes_Peak">Pike's Peak</a>, <st1:state>Colorado</st1:state>.
Some spectacular specimens displaying amazonite along with smoky quartz
crystals in a matrix of albite and orthoclase feldspar have been found around <st1:place>Pike’s
Peak</st1:place>. Another area where amazonite is found in <st1:state><st1:place>Colorado</st1:place></st1:state>
is at <a href="http://en.wikipedia.org/wiki/Crystal_Peak_(Tenmile_Range)">Crystal
Peak</a> in <st1:place><st1:placename>El Paso</st1:placename> <st1:placetype>County</st1:placetype></st1:place>.
There are other places in the <st1:country-region><st1:place>United States</st1:place></st1:country-region>
were amazonite has been found associated with pegmatites like it is in <st1:state><st1:place>Colorado</st1:place></st1:state>.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Amazonite-cut.jpg/634px-Amazonite-cut.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="377" src="http://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Amazonite-cut.jpg/634px-Amazonite-cut.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Amazonite cut in cabochon.<br />
Photo by Eurico Zimbres</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
For many years many people assumed that the bright green
color of amazonite was because of copper compounds that are often similarly
colored having bright blue or green colors. Recent studies that have been
undertaken suggest that the blue-green colors of amazonite are actually caused
by a small amount of lead and water as <a href="http://en.wikipedia.org/wiki/Crystallographic_defect">crystal defects</a>
in the feldspar.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/4/49/Srebro_-_naszyjnik_-_Skarabeusz_nr_1.png/800px-Srebro_-_naszyjnik_-_Skarabeusz_nr_1.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="202" src="http://upload.wikimedia.org/wikipedia/commons/thumb/4/49/Srebro_-_naszyjnik_-_Skarabeusz_nr_1.png/800px-Srebro_-_naszyjnik_-_Skarabeusz_nr_1.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A lapis lazuli pectoral made in Ancient Egypt. A small piece of amazonite can be seen as the round stone at the bottom of the pectoral.<br />
Photo by Henryk Jan Dominiak </td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Amazonite has been used for years when it has been cut and
polished as a gemstone, but as gem it is not advisable to use this in the rings
because it is brittle and fractures is easily.
However, when cut <a href="http://en.wikipedia.org/wiki/Cabochon">en
cabochon</a> is readily finds use in pendants and lockets. Large masses of this stone are used for <a href="http://en.wikipedia.org/wiki/Stone_carving">carving</a>. </div>
<div class="MsoNormal">
<br /></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com3tag:blogger.com,1999:blog-3427371516505437050.post-76995462004772852952012-02-24T21:20:00.001-08:002012-02-24T21:20:16.459-08:00Apatite as a gemstone<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/2/22/Apatite-(CaF)-Calcite-290699.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="361" src="http://upload.wikimedia.org/wikipedia/commons/2/22/Apatite-(CaF)-Calcite-290699.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A crystal of gemmy apatite on a matrix of quartz.<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://en.wikipedia.org/wiki/Apatite">Apatite</a>
is a whole family of minerals some of them are gems, but the place where you
are most familiar with is your teeth and skeleton that are composed of <a href="http://en.wikipedia.org/wiki/Hydroxylapatite">hydroxalapatite</a>. Basically apatite is composed of calcium
phosphate with extra ions added to its crystalline structure to cause it to be
known as several related names: flourapatite, chlorapatite, bromapatite and in
the case of your bones the OH ion. Apatite is used as the defining mineral for
number five on the <a href="http://geology.about.com/od/scales/a/mohsscale.htm">Moh’s
hardness scale</a>. Hydroxyapatite is a relatively rare form of the mineral are
mostly groups are absent or contain many carbonate and acid phosphate
substitutes that form a large part of bone material.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/b/b9/Apatite-164910.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/b/b9/Apatite-164910.jpg" width="292" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A twinned crystal of Apatite<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://www.mindat.org/min-1572.html">Flourapatite</a>
is much more resistant to acid attack than hydroxyapatite it is for this reason
that fluorine is added to your drinking water and can also be found in your
toothpaste. In the case of the fluoridated water it allows the interchange of
fluoride ions that substitute for hydroxyapatite ions. If you get too much
fluoride into your system it can result in dental or skeletal flouresis.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<a href="http://geology.cr.usgs.gov/capabilities/gronemtrac/geochron/fission/tech.html">Fission
tracks</a> are used by geochemists and geophysicists for determining the
thermal history of orogenic belts and settlements in sedimentary basins. This
is because as a trace element uranium and thorium are found in crystalline
apatite. The same phenomenon is also used in paleontology to establish the
dates of prehistoric wildfires.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Strontiumapatite-ge04c.jpg/105px-Strontiumapatite-ge04c.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Strontiumapatite-ge04c.jpg/105px-Strontiumapatite-ge04c.jpg" width="350" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A faceted gemstone of apatite.<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Apatite in phosphorite is a phosphorus rich sedimentary rock
containing between 18 and 40% of phosphorus pentoxide (P<sub>2</sub>O<sub>5</sub>).
A great deal of the phosphorite is mined in central <st1:state><st1:place>Florida</st1:place></st1:state>
in an area that is called “<a href="http://en.wikipedia.org/wiki/Bone_Valley">Bone
Valley</a>” for use as fertilizer. It contains so much uranium that during the
Cold War if supplied several thousand tons of yellowcake uranium to the Atomic
Energy Commission. The piles of mine slimes resulting from mining and refining
this phosphorite presents a serious <a href="http://en.wikipedia.org/wiki/Environmental_hazard">environmental hazard</a>
not only from the uranium, but also from the contained fluorides. The apatite
contained in phosphorite is in crypto- crystalline masses that are called
colophane. Apatite is also mined from igneous rocks in the <a href="http://en.wikipedia.org/wiki/Kola_Peninsula">Kola Peninsula</a> of
northeast <st1:country-region><st1:place>Russia</st1:place></st1:country-region>
as a fertilizer as well..</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Clear crystals of apatite can be faceted creating an
extremely handsome gem. Because of the sensitivity to heat and shock gems that
are cut from apatite are never heat-treated to improve their looks. Although
apatite is found all over the world most of it is small crystals disseminated
through the rocks; larger crystals are quite rare. Most of the faceting grade
apatite crystals are shades of blue, although some are blue-green.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/1/18/Hornblendite_with_apatite.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="277" src="http://upload.wikimedia.org/wikipedia/commons/1/18/Hornblendite_with_apatite.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A thin section of hornblende and apatite<br />Photo by Pitor Sosnowski</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Most of this faceting material is found in metamorphosed
limestone that is commonly called marble. In general the more impurities that
are found in limestone the more apt it is to produce apatite when it is
metamorphosed. There is a bed of metamorphosed limestone that reaches all the
way from Québec to <st1:state><st1:place>Alabama</st1:place></st1:state> just
of the West of the Precambrian core of the <st1:place>Appalachians</st1:place>.
In many places this is called the <a href="http://en.wikipedia.org/wiki/Great_Appalachian_Valley">Great Valley</a>
of the <st1:place>Appalachians</st1:place> but the same marble belt extends all
the way to <st1:country-region><st1:place>Canada</st1:place></st1:country-region>.
There is apatite found throughout this entire region, and others like it all
over the world.</div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com3tag:blogger.com,1999:blog-3427371516505437050.post-39856518745715542392012-02-23T19:25:00.001-08:002012-02-23T19:25:08.125-08:00Almandine Garnets<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/3/37/Almandine_-_Russel_Garnet_mine,_Hampden_County,_Massachusetts,_USA.jpg/591px-Almandine_-_Russel_Garnet_mine,_Hampden_County,_Massachusetts,_USA.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/3/37/Almandine_-_Russel_Garnet_mine,_Hampden_County,_Massachusetts,_USA.jpg/591px-Almandine_-_Russel_Garnet_mine,_Hampden_County,_Massachusetts,_USA.jpg" width="393" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A cluster of almandine garnets in matrix.<br />Photo by Rock Currier</td></tr>
</tbody></table>
<div class="MsoNormal">
<a href="http://en.wikipedia.org/wiki/Almandine">Almandine</a>
is a member of the <a href="http://factoidz.com/the-garnet-family-of-gemstones-pyrope-almandine-spessartine-and-grossular/">garnet
family</a> that was known to the ancient <a href="http://en.wikipedia.org/wiki/Roman_Empire">Romans</a> where it was
pronounced “alabandicus” where it was known to <a href="http://www.google.com/search?rlz=1C1CHMQ_en___US311&aq=f&sourceid=chrome&ie=UTF-8&q=pliny+the+elder">Pliny
the Elder</a>. This was a stone that was either found near or worked at the
town of <st1:city><st1:place>Alabanda</st1:place></st1:city> a town in Cariua
in <st1:place>Asia Minor</st1:place>. In composition it is an iron aluminum
garnet possessing a deep red color that inclines toward purple. Almandine as a
stone entering the <a href="http://www.gemvara.com/Red-Garnet-Jewelry/jewelry/b/gemstones-red-garnet/?gclid=CPudpPP2jKQCFdJL5QodLCmOLA">jewelry
trade</a> is either <a href="http://www.google.com/search?rlz=1C1CHMQ_en___US311&aq=f&sourceid=chrome&ie=UTF-8&q=pliny+the+elder">faceted</a>
or cut with a convex face en cabochon when it is then called a carbuncle. When
the stone was viewed through a <a href="http://www.thefreedictionary.com/spectroscope">spectroscope</a> in a
strong light, it generally shows that has three characteristic <a href="http://en.wikipedia.org/wiki/Absorption_band">absorption bands.<o:p></o:p></a></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The stone is one end member of a solid solution series the
other end up being the <a href="http://en.wikipedia.org/wiki/Pyrope">pyrope</a>
garnet that is magnesium rich rather than iron. The chemical formula for
almandine garnets is: Fe<sub>3</sub>Al<sub>2</sub>Si<sub>3</sub>O<sub>12</sub>.
The solid solution occurs when magnesium substitutes for the iron causing an
increasingly rich pyrope composition. Almandine is the ferrous iron member of
the class of garnet minerals that are important group of rock forming silicates
that are the main <a href="http://jersey.uoregon.edu/~mstrick/AskGeoMan/geoQuerry30.html">rock
forming minerals</a> in the <a href="http://geology.about.com/od/platetectonics/a/thecrust.htm">Earth's crust</a>.
<st1:city><st1:place>Crystals</st1:place></st1:city> of almandine are often
seen in mica schist fillet very much like raisins in a pudding. This type of
garnet crystallizes in the cubic space group Ia3d having a that a cell
parameter of 11.512 Å at 100° <a href="http://en.wikipedia.org/wiki/Kelvin">Kelvin.</a></div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Almandine-40514.jpg/298px-Almandine-40514.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Almandine-40514.jpg/298px-Almandine-40514.jpg" width="197" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A gemmy red almandine garnet on a matrix of mica schist<br />Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Almandine can be found rather abundantly in gem gravels
found in <a href="http://en.wikipedia.org/wiki/Sri_Lanka">Sri_Lanka</a>, but
are actually pretty abundant in any stream gravel that is found adjacent to
metamorphic or igneous rock. In this case almandine garnets are a constituent
of the black sand that are classified as stream heavies. Sometimes almandine
garnets are so abundant on beaches that they are mind commercially for their
abrasive qualities.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
In the gem trade almandine garnets have gone by many names
among them are <st1:country-region><st1:place>Ceylon</st1:place></st1:country-region>
ruby. If their color takes a violet tint the stone is sometimes called a Syrian
Garnet. Large deposits of some especially fine album being garnets were found
in the Northern Territory of Australia that were marketed for years as
Australian rubies. An especially interesting variety of the stone that is found
in stream gravel's in parts of <st1:state><st1:place>Idaho</st1:place></st1:state>
show a star when they are cut, and marketed as star garnets.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/e/ea/Costume_jewelry_of_Constance_of_Austria.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="305" src="http://upload.wikimedia.org/wikipedia/commons/e/ea/Costume_jewelry_of_Constance_of_Austria.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A collection of jewlery in Kracow, Poland made from pearls, diamonds, almandine garnet and enamel.<br />Photo by S.F. Burgerer</td></tr>
</tbody></table>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
<o:p><br /></o:p></div>
<div class="MsoNormal">
As a mineral almandine is widely distributed throughout the
world with fine rhombic crystals that are called to <a href="http://en.wikipedia.org/wiki/Dodecahedron">dodecahedra</a> that are found
in the schistose rocks wherever crystalline bedrock is found. In</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
One of the best localities in the <st1:country-region><st1:place>United
States</st1:place></st1:country-region> is located at <st1:place><st1:placename>Gore</st1:placename>
<st1:placetype>Mountain</st1:placetype></st1:place> in the <a href="http://en.wikipedia.org/wiki/Adirondack_Mountains">Adirondack mountains</a>
of <st1:place><st1:placename>New York</st1:placename> <st1:placetype>State</st1:placetype></st1:place>
at the town of <st1:city><st1:place>North</st1:place></st1:city> Creek. Some of
the crystals that are found enclosed in <a href="http://en.wikipedia.org/wiki/Gabbro">gabbro</a> are more than a meter
across they are mined by the <st1:place><st1:placename>Gore</st1:placename> <st1:placetype>Mountain</st1:placetype></st1:place>
mining company that crushes them for <a href="http://en.wikipedia.org/wiki/Abrasive">abrasives</a>. Many of these
garnets from this particular deposit are faceting grade and makes an extremely
attractive gems.</div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com2tag:blogger.com,1999:blog-3427371516505437050.post-43776965119392969962012-02-20T07:54:00.001-08:002012-02-20T07:54:18.146-08:00Aquamarine as a Gemstone<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<div class="MsoNormal">
<a href="http://www.bernardine.com/gemstones/aquamarine.htm">Aquamarine</a> is a member of the <a href="http://www.mindat.org/min-819.html">beryl</a> family of gemstones that
is usually colored various shades of blue/green or may appear as either light
green or even as dark blue stones rivaling sapphire in color. The mineral is a beryllium aluminum
cyclosilicate with the formula Be<sub>3</sub>Al<sub>2</sub>(SiO<sub>3</sub>)<sub>6</sub>. <a href="http://www.crystalworlds.com/Meaning_Double_Terminated.htm">Terminated crystals</a> of beryl are relatively
rare, but are known to occur. The stone
has a value as a gemstone, and is a common ore of the metal beryllium. In the case of aquamarine a small amount of
iron that causes crystal defects in the crystal is the cause of its color. The mineral beryl because of impurities in
the crystal does occur in several different colors including green blue, yellow,
red and white.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/e/ee/Beryl-118637.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="345" src="http://upload.wikimedia.org/wikipedia/commons/e/ee/Beryl-118637.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Aquamarine in a matrix of feldspar crystals.and other minerals including schorl the black crystal in the middle of the specimen.<br />
Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal" style="text-align: center;">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
The colors of aquamarine can range from light blue like that
of the sky to a deep blue of the sea.
The darker the color the higher the price some aquamarines can sell for
as much as $2,000 per caret although lighter stones only fetch a few dollars
per carat. The stone itself is
fascinatingly beautiful with much appeal to women all over the world because it
can complement or eye color. For
creative gemstone cutters it is an inspiration because of its ability to be cut
in so many designs and still keep its beauty.</div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/1/18/Beryl-271353.jpg/337px-Beryl-271353.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/18/Beryl-271353.jpg/337px-Beryl-271353.jpg" width="225" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A water etched crystal of aquamarine from Brazil<br />
Photo by Rob Lavinsky</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Aquamarine is epitomized by its blue color, and the deeper
blue the color the more expensive the stone making it one of the most popular
stones rivaling at times its more expensive cousin emerald that also belongs to
the beryl family. The stone is hard
enough at Mohs hardness of 7.5 to 8 so it can be used in most types of jewelry
making it almost as popular as the classic stones emerald, ruby and
sapphire. In reality aquamarine is
related to the emerald, but unlike its more famous cousin it usually free of
flaws. One flaw that is sometimes seen
in aquamarine is long thin tubes that sometimes lend to its beauty in the form
of <a href="http://en.wikipedia.org/wiki/Chatoyancy">chatoyancy</a> forming tiger eyes or more rarely a star stone much like star
sapphire. Both forms of the stone command
very high prices. </div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/1/16/Aquamarin_cut.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="293" src="http://upload.wikimedia.org/wikipedia/commons/1/16/Aquamarin_cut.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An example of a pear shaped aquamarine faceted gem.<br />
Photographer Unknown</td></tr>
</tbody></table>
<div class="MsoNormal" style="text-align: center;">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
The color of aquamarine is caused by ions of iron causing
crystal defects in the mineral beryl that is normally clear that is called
<a href="http://www.mineralszone.com/gemstones/goshenite.html">goshenite</a> my mineralogists because its type locality is in Goshen,
Massachusetts were it is found in lithium bearing pegmatites. Aquamarine can range from a pale blue to a
strongly colored sea blue. In some
aquamarines you can see a light greenish simmer that is a typical feature of
the stone. Thee most prized color
however is a pure clear blue transparent stone bringing out the transparency
and shine of this magnificent stone.</div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com2tag:blogger.com,1999:blog-3427371516505437050.post-51044727975544481492012-02-17T03:50:00.002-08:002012-02-17T03:51:26.956-08:00The Royal Purple Stone Amethyst<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<div class="MsoNormal">
At one time the amethyst was considered to be a precious
stone and was even found among the crown jewels of <st1:country-region><st1:place>France</st1:place></st1:country-region>.
This particular stone came from the basalt outcrops along the <st1:place>Bay of
Fundy</st1:place> near <st1:place><st1:city>Parsboro</st1:city>, <st1:state>Nova
Scotia</st1:state></st1:place>. </div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/5/57/FrenchCrownJewelsLouvre-1.jpg/794px-FrenchCrownJewelsLouvre-1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="301" src="http://upload.wikimedia.org/wikipedia/commons/thumb/5/57/FrenchCrownJewelsLouvre-1.jpg/794px-FrenchCrownJewelsLouvre-1.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The French Crown Jewels that are kept in the Louvre</td></tr>
</tbody></table>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
Amethyst is a form of quartz that has a hardness of seven
making it suitable for jewelry and when cut it takes a very high polish.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/5/56/Kryszta%C5%82_ametystu_Brazylia_Rio_Grande_do_Sul.jpg/513px-Kryszta%C5%82_ametystu_Brazylia_Rio_Grande_do_Sul.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/5/56/Kryszta%C5%82_ametystu_Brazylia_Rio_Grande_do_Sul.jpg/513px-Kryszta%C5%82_ametystu_Brazylia_Rio_Grande_do_Sul.jpg" width="342" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An amethyst crystal from Brazil</td></tr>
</tbody></table>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
Among the many forms of crystals that it takes is one
special type called scepter crystals that form with a narrow bottom that widens
at the top.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/5/5f/Amethist_quartz.jpeg/463px-Amethist_quartz.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/5/5f/Amethist_quartz.jpeg/463px-Amethist_quartz.jpeg" width="307" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A scepter crystal of amethyst.</td></tr>
</tbody></table>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
A common form for amethyst to take is the lining of the
geode. The best place in the world to find these amethyst geodes is in the
basalt flows of <st1:country-region><st1:place>Uruguay</st1:place></st1:country-region>
that formed as bubbles in the basalt as it was cooling.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/6/63/Amethyste_geode.jpg/400px-Amethyste_geode.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/6/63/Amethyste_geode.jpg/400px-Amethyste_geode.jpg" width="266" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An amethyst filled geode from Uruguay. In this case the crystals form a druse inside a bubble formed in basalt. Note the green iron staining in the outside of the geode. The geodes are eroded from the basalt flow and are found lying on the soil.<br />
Photo by Didier Descouens</td></tr>
</tbody></table>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
At other times it is just found cavity. </div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/7/77/Druse.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="201" src="http://upload.wikimedia.org/wikipedia/commons/7/77/Druse.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This is a druse of amethyst found in a small geode.</td></tr>
</tbody></table>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
When amethyst is cut the stone was usually faceted one of
forms it takes is an emerald cut although there are many other types of faceted
stones that it can take.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/3/36/Amethyst_cut.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="353" src="http://upload.wikimedia.org/wikipedia/commons/3/36/Amethyst_cut.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An emerald cut amethyst</td></tr>
</tbody></table>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
Some amethyst is cut in the intaglio style something like a
cameo only the surface of the stone has the design incised.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/8/8e/Intaille_en_am%C3%A9thyste.JPG/438px-Intaille_en_am%C3%A9thyste.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/8/8e/Intaille_en_am%C3%A9thyste.JPG/438px-Intaille_en_am%C3%A9thyste.JPG" width="291" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An intaglio cut amethyst.</td></tr>
</tbody></table>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
For centuries amethyst is then used in jewelry as a faceted
stone or en cabochon. It</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/a/a8/Ametystring.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="347" src="http://upload.wikimedia.org/wikipedia/commons/a/a8/Ametystring.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A ring with an amethyst stone.</td></tr>
</tbody></table>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
Sometimes amethyst if the crystal is large enough is carved
in the statues. The Chinese are particularly adept at this artform.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/f/f4/Vaso_de_jaspe_con_Neptuno_y_caracol_(Prado_O-54)_01b.jpg/527px-Vaso_de_jaspe_con_Neptuno_y_caracol_(Prado_O-54)_01b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/f4/Vaso_de_jaspe_con_Neptuno_y_caracol_(Prado_O-54)_01b.jpg/527px-Vaso_de_jaspe_con_Neptuno_y_caracol_(Prado_O-54)_01b.jpg" width="351" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">an antique vase made in the 1600s containing many different stones including amethyst.<br />
<br />
<div style="text-align: left;">
<span style="font-size: small;">Photos from Wikimedia Commons</span></div>
</td></tr>
</tbody></table>
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
</div>Geotekhttp://www.blogger.com/profile/10726009423220137783noreply@blogger.com2