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The
current featured stone: |
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Axinite |
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| Refractive Index:
1.672-1.704 |
Crystal Structure:
Triclinic |
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| Hardness: 6
1/2 - 7 |
Specific Gravity:
3.18-3.37 |
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Chemical
Composition:
(Ca,Mn)2(Fe,Mn,Mg)
Al2BSi4O15OH
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Occurrences:
Mexico, Pakistan, Tanzania, California |
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| The name Axinite
refers to a group of borosilicate minerals that make an uncommon gem
material. The stones are sufficiently hard for use in jewelry, as is
often the case the material is simply to rare to find a meaningful place on
the market. That said, there has been enough of the this gem available
in the last couple of years, primarily from finds in Pakistan, that we
thought it merited a write-up. Looking at the first photo, you make be
inclined to think of Axinite as just another scarce brown gem with little to
make things more interesting. It's true that there are lot of rare,
brown stones. The next photo should help with that a bit:
Axinite has a strong directional color, or pleochroism, and one of these
colors can be an intense purple. The combination of brown bodycolor
with strong flashes of purple is highly unusual and quite lovely.
There is even more to the story. As
mentioned, Axinite refers to a group of minerals that are the same
structurally but can differ based on the percentage of other elements
present. Most gem Axinite has a high percentage of iron and is
therefore known as Ferro-Axinite. These are the primarily deep brown
gems that are most frequently encountered. Attractive examples of
Magnesio-Axinite have also been discovered in gem quality in the last
several years - interestingly enough at the Tanzanite deposits in Merelani,
Tanzania. These stones have a strikingly different visual appearance -
they tend to be pink-purple (see the double photos below) and will exhibit a
color shift.
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| Deposits in Baja, California
have produced gem Axinites for collectors for many decades, but only
recently have more significant finds in Pakistan allowed larger, cleaner
gems to be faceted. Finally, what's in
a name? Axinite comes from the unusual flattend, wedge shape of the
crystals themselves (see right). While these distinctive beauties are
great for collectors, they tend to limit the available size of finished
gems. Flat crystals make for very poor yields when faceting.
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