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<TD><H1><A HREF=http://store.unconventionallapidarist.com/Category685>Lapidary Rough</A> / Iolite</H1></TD>
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<P><p><b>Cordierite</b> (mineralogy) or <b>iolite</b> (gemology) is a magnesium iron aluminium cyclosilicate. Iron is almost always present and a solid solution exists between Mg-rich cordierite and Fe-rich sekaninaite with a series formula: (Mg,Fe)<sub>2</sub><span class="mw-redirect">Al</span><sub>3</sub>(Si<sub>5</sub>AlO<sub>18</sub>) to (Fe,Mg)<sub>2</sub>Al<sub>3</sub>(Si<sub>5</sub>AlO<sub>18</sub>)<sup id="cite_ref-0" class="reference"><span>[</span>1<span>]</span></sup>. A high temperature polymorph exists, <span class="new">indialite</span>, which is isostructural with beryl and has a random distribution of Al in the (Si,Al)<sub>6</sub>O<sub>18</sub> rings.<sup id="cite_ref-1" class="reference"><span>[</span>2<span>]</span></sup></p>
<p>Cordierite is named after the French geologist P. L. A. Cordier (1777 - 1861).</p>
<p>As the transparent variety iolite, it is often used as a gemstone. The name "iolite" comes from the Greek word for violet. Another old name is <i>dichroite</i>, a Greek word meaning "two-colored rock", a reference to cordierite's strong pleochroism.
It has also been called "water-sapphire" and "Vikings' Compass"
(because of its ability to determine the direction of the sun on
overcast days<sup class="noprint Template-Fact"><span title="This claim needs references to reliable sources since October 2008" style="white-space: nowrap;"></span></sup>). Gem quality iolite varies in color from sapphire blue to blue violet to yellowish gray to light blue as the light angle changes.</p>
<p>Iolite is sometimes used as an inexpensive substitute for sapphire. It has a low price tag because it is much softer than sapphires<sup id="cite_ref-5" class="reference"><span></span><span></span></sup>
and is abundantly found in Sri Lanka, India, Burma, Australia's
Northern Territory, Namibia, Brazil, Tanzania, Madagascar, Connecticut,
and the Yellowknife area of the Northwest Territories of Canada.</p>
<font class="font2">This article is licensed under the
<a target="_blank" rel="nofollow" title="http://www.gnu.org/copyleft/fdl.html" class="external text" href="http://www.gnu.org/copyleft/fdl.html">GNU Free Documentation License</a>.
It uses material from the <a target="_blank" rel="nofollow" title="http://en.wikipedia.org/wiki/Iolite" class="external text" href="http://en.wikipedia.org/wiki/Iolite">Wikipedia article "Iolite"</a></font></P>
<BR clear=left><BR><P><A HREF=http://store.unconventionallapidarist.com/Product13369 TITLE="Iolite Rough"><IMG SRC="https://store.nexternal.com/lapidarist/images/ioltrgh1003-01.jpg" ALIGN=left ALT="Iolite Rough" NAME="Iolite Rough" BORDER=0></A>
<A HREF=http://store.unconventionallapidarist.com/Product13369 TITLE="Iolite Rough">Iolite Rough</A>
-- <B>$12.00</B>
-- Iolite Rough( 0.79" x 0.63" x 0.54" )</P>
<BR clear=left><BR><P><A HREF=http://store.unconventionallapidarist.com/Product13370 TITLE="Iolite Rough"><IMG SRC="https://store.nexternal.com/lapidarist/images/ioltrgh1005-01.jpg" ALIGN=left ALT="Iolite Rough" NAME="Iolite Rough" BORDER=0></A>
<A HREF=http://store.unconventionallapidarist.com/Product13370 TITLE="Iolite Rough">Iolite Rough</A>
-- <B>$6.00</B>
-- Iolite Rough( 0.67" x 0.56" x 0.41" )</P>
<BR clear=left><BR><P><A HREF=http://store.unconventionallapidarist.com/Product13371 TITLE="Iolite Rough"><IMG SRC="https://store.nexternal.com/lapidarist/images/ioltrgh1006-01.jpg" ALIGN=left ALT="Iolite Rough" NAME="Iolite Rough" BORDER=0></A>
<A HREF=http://store.unconventionallapidarist.com/Product13371 TITLE="Iolite Rough">Iolite Rough</A>
-- <B>$5.00</B>
-- Iolite Rough( 0.68" x 0.55" x 0.34" )</P>
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