Prosopite Value, Price, and Jewelry Information

Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons

Prosopite

An overview on Prosopite Jewelry and Gemstones. Covers details and essential information on the physical properties and characteristics of Prosopite gems.

Prosopite Information

Data Value
Name Prosopite
Stone Sizes Prosopite is a nondescript mineral of no gem significance, except for the beautiful blue material from Zacatecas, Mexico. This material is turquoise-blue, with density variable from 2.69-2.85. Distinction from turquoise is chiefly based on the lower refractive index (1.50 vs. 1.62 for turquoise). Mexican prosopite is evenly colored due to approximately 1.4% copper content. It makes an effective and attractive turquoise substitute.
Formula CaAl2(F,OH)8.  
Colors Colorless, white, gray.
Fracture Conchoidal
Hardness 4.5
Cleavage Perfect; not seen on massive material
Crystallography Monoclinic; crystals minute, tabular; commonly massive, granular.
Refractive Index 1.501-1.510
Birefringence 0.009
Luminescence None reported.
Luminescence Present No
Absorption Spectrum Not diagnostic.
Pleochroism None.
Optics a = 1.501; β = 1.503; γ = 1.510. Biaxial (+).
Optic Sign Biaxial +
Luster Vitreous to dull.
Specific Gravity 2.88
Transparency Transparent to translucent.

Optics: a = 1.501; β=1.503; γ=1-510

Biaxial (+).

Occurrence: In tin veins, alkalic pegmatites, and as an alteration product of topaz in volcanic rocks.

St. Peters Dome, El Paso County, Colorado: cryolite deposit.

Dugway district, Tooele County, Utah: greenish color due to a trace of copper.

Santa Rosa, Zacatecas, Mexico: associated with azurite; blue material.

Germany; Tasmania.

Name: From a Greek word meaning a mask, in allusion to the deceptive nature of the material when found as pseudomorphs.

by Joel E. Arem, Ph.D., FGA