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[proo-stahyt] /ˈpru staɪt/
noun, Mineralogy
a mineral, silver arsenic sulfide, Ag 3 AsS 3 , occurring in scarlet crystals and masses: a minor ore of silver; ruby silver.
1825-35; named after J. L. Proust; see -ite1 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for proustite


a red mineral consisting of silver arsenic sulphide in hexagonal crystalline form. Formula: Ag3AsS3
Word Origin
C19: from French, named after Joseph Louis Proust (1754–1826), French chemist
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Encyclopedia Article for proustite

a sulfosalt mineral, silver arsenic sulfide (Ag3AsS3), that is an important source of silver. Sometimes called ruby silver because of its scarlet-vermilion colour, it occurs in the upper portions of most silver veins, where it is less common than pyrargyrite. Large, magnificent crystals, of hexagonal symmetry, have been found at Chanarcillo, Chile; other notable localities are Lorrain, Ont., and Freiberg and Marienberg, Ger. It is mined as a silver ore in Mexico and is found in small amounts in the silver mines of the western United States. For detailed physical properties, see sulfosalt (table)

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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