- Proustite
Proustite is a sulfosalt
mineral consisting ofsilver sulfarsenide, Ag3AsS3, known also as light red silver or ruby silver ore, and an important source of the metal. It is closely allied to the corresponding sulfantimonide,pyrargyrite , from which it was distinguished by the chemical analyses ofJ. L. Proust in1804 , after whom the mineral received its name.Many of the characters being so similar to those of pyrargyrite they are mentioned under that species. The prismatic crystals are often terminated by the scalenohedron and the obtuse rhombohedron, thus resembling
calcite (dog-tooth-spar) in habit. The color isscarlet -vermilion and the lustreadamantine ;crystal s are transparent and very brilliant, but on exposure to light they soon become dull black and opaque. The streak is scarlet, the hardness 2.5, and thespecific gravity 5.57.The mode of occurrence is the same as that of
pyrargyrite , and the two minerals are sometimes found together. Magnificent groups of large crystals have been found atChañarcillo inChile ; other localities which have yielded fine specimens are Freiberg andMarienberg inSaxony ,Joachimsthal inBohemia andMarkirch inAlsace .ee also
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List of minerals
*List of minerals named after people
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