An overview on Prosopite Jewelry and Gemstones. Covers details and essential information on the physical properties and characteristics of Prosopite gems.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Crystallography||Monoclinic; crystals minute, tabular; commonly massive, granular.|
|Colors||Colorless, white, gray.|
|Cleavage||Perfect; not seen on massive material; fracture conchoidal.|
|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.|
Optics: a = 1.501; β=1.503; γ=1-510
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.
Name: From a Greek word meaning a mask, in allusion to the deceptive nature of the material when found as pseudomorphs.