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Historical Information

Prosopite is named from the Greek word prosopon meaning mask in allusion to the deceptive character of mineral (as pseudomorphs).

Prosopite is a rare halide mineral that is commonly found as granular or powdery masses or as minute colorless crystals to about 6 mm. Prosopite is usually a nondescript mineral of no gem significance except for the beautiful turquoise to sky blue material found at the Santa Rosa Mine, Noche Buena, Zacatecas, Mexico This source has produced small quantities of massive material of turquoise to sky blue that can be made into beautiful cabochons (see picture above). This is the only location to produce such beautiful blue material large enough for gem use. Blue Prosopite from Zacatecas, Mexico may appear very similar to light colored Turquoise fromvarious sources.

Distinction from Turquoise is mainly based on the lower refractive index (1.50 vs. 1.62 for Turquoise). This blue Prosopite gets its color from approximately 1.4% Copper content.

Prosopite is found at the following localities: In Germany, from Altenberg, Saxony. At HornĂ­ Slavkov (Schlaggenwald), Czech Republic. From Perga, Volyn, Ukraine. In Russia, from Miass, Ilmen Mountains, Southern Ural Mountains; on the Yenisei Ridge, Siberia; and in the Zharchikhinsk molybdenum deposit, on the west side of Lake Baikal, eastern Siberia. In the Ivigtut cryolite deposit, southwestern Greenland. From Mt. Bischoff, Tasmania, Australia. In the USA, at St. Peters Dome, near Pikes Peak, El Paso County, and in the Goldie carbonatite, McClure Mountain-Iron Mountain, Fremont County, Colorado; in the Dugway district, Tooele County, Utah; at the Zapot pegmatite, 25 km northeast of Hawthorne, Fitting district, Mineral County, Nevada; from the Grand Reef mine, Aravaipa district, Graham County, and 16 km north of Bouse, La Paz County, Arizona; in the Morefield pegmatite mine, Amelia, Amelia County, Virginia. In Mexico, at the Santa Rosa mine, Mazapil, Zacatecas, Mexico. From Tsumeb, Namibia.