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The
current featured stone: |
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Wulfenite |
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| Refractive Index:
2.405-2.283 |
Crystal Structure:
Tetragonal |
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| Hardness: 3 |
Specific Gravity:
6.50-7 |
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Chemical
Composition:
PbMoO4
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Occurrences:
Mexico, Morocco, Namibia, Arizona |
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| Where does one
begin with a discussion of Wulfenite as a gem material? It's a
collector's gem to be sure, indeed it's a classic "rare stone" in that it is
too fragile to see use in jewelry. It is also too tempting to resist
for those brave souls willing to facet it - the sheer intensity of color and
optical properties of Wulfenite make finished gems visual knockouts.
As such, fine examples have been, and continue to be of interest to
collectors.
Specimen collector's know Wulfenite well.
As a mineral, it is not terribly uncommon and its thin, tabular crystals are
easily spotted at mineral shows the world over. It is in the nature of
these crystals that we have another reason for the rarity of faceted
Wulfenite; although sometimes quite gemmy, the crystals are often much too
thin for cutting. Take a look at the photo below for a gem that was to
follow the morphology of the typical Wulfenite crystal.
Gems have been cut from Wulfenite crystals from
a number of localities. From Arizona come the intense reddish oranges,
the pure oranges are typically Mexican, while the trove of the Tsumeb
deposit has given us colorless, light yellow and even blue Wulfenites.
The unusual inky-blue stones were part of an extremely limited find at
Tsumeb and, as yet, have not been found elsewhere.
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The Los Lamentos Mountains of
Chihuahua, Mexico have proved to be a decent source of facet grade rough -
the crystals from this locality are generally thicker than what is typical.
If not for pieces from this deposit, finished stones would be even more
scarce in the market. So,
you have the high optical properties and a superb range of very saturated
colors. The problem of course is the hardness, at only 3 (at best) on
the Moh's scale, we have to move Wulfenite to the collector's cabinet only.
Still, it is hard no to appreciate it as a gem material, albeit a rare and
delicate one. |
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Yellow (Congo) and colorless Wulfenite
(Tsumeb) flank an image of Franz Xaver von Wulfen for whom the mineral is
named |
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