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Triplite



Triplite

General
CategoryPhosphate mineral
Chemical formula(Mn,Fe)2(PO4)(F,OH)
Identification
ColorBrown, Salmon, Red
Crystal habitPrismatic, Massive to granular
Crystal systemMonoclinic
CleavageGood
FractureUneven - Flat surfaces
Mohs Scale hardness5
LusterResinous - Greasy
Refractive indexnα=1.650, nβ=1.660, nγ=1.680
StreakYellowish gray
Specific gravity3.44 - 3.9

Triplite (Mn,Fe2+)2(PO4)(F,OH) is a rare mineral that forms in phosphate-rich granitic, pegmatites typically as iregular brown opaque masses. Triplite was first described in 1813 for an occurrence in Chanteloube, Limousin, France. [1] The name is from the Greek triplos for triple, in reference to the three cleavage directions. It has rather low hardness for a gemstone, at 5-5.5 on the Mohs scale. In color and appearance, it is very similar to rhodocrosite, another manganese bearing mineral. Chemically, it is also quite similar to triploidite the difference being that triplite is F dominant while triploidite is OH dominant.

Additional recommended knowledge

Triplite is quite rare and difficult to facet due to its brittleness and cleavage. Only a few cut stones have been reported and all of them are from the Shigar Valley in Pakistan. One specimen from Dudley Blauwet was loaned to the GIA for examination. General absorption to 450nm, weak absorption bands at 470nm and 490nm and a stronger band at 520 – 620nm were observed with a desk model spectroscope. Microscopic inspection revealed finger print type and two phase inclusions. [2]


Occurrence

Triplite (Mn,Fe2+)2(PO4)(F,OH) is a rare fluoro-hydroxide phosphate mineral that forms in phosphate rich granite pegmatites and high temperature hydrothermal veins. Found in the United States in California, Nevada, Arizona, Colorado, South Dakota, Virginia, Connecticut, and Maine. Other occurrences include the Shigar Valley, Pakistan; China; Bavaria, Germany; Kimito, Finland and Karibib, Namibia. [3]


See also


References

  1. ^ Triplite Crystals from Colorado, C. W. Wolf and E. Wm. Heinrich, American Mineralogist, Volume 32, pages 518-526, 1947
  2. ^ Triplite classification (2006, June 05). In Multicolour Gemstones Library.
  3. ^ Rare gem triplite specimen discovered in Tucson. (2006, June 05). Multicolour Gem Ltd. Retrieved online 07:45, June 05, 2007
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Triplite". A list of authors is available in Wikipedia.
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