Prosopite Value, Price, and Jewelry Information


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

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

Prosopite Value

The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.

Prosopite Information

DataValue
NameProsopite
Crystallography Monoclinic; crystals minute, tabular; commonly massive, granular.
Refractive Index 1.501-1.510
Colors Colorless, white, gray.
Luster Vitreous to dull.
Fracture Conchoidal
Hardness 4.5
Specific Gravity 2.88
Birefringence 0.009
Cleavage Perfect; not seen on massive material
Stone SizesProsopite 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.
Luminescence None reported.
Transparency Transparent to translucent.
Absorption Spectrum Not diagnostic.
FormulaCaAl2(F,OH)8.  
Pleochroism None.
Optics a = 1.501; β = 1.503; γ = 1.510. Biaxial (+).

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.