Proustite
Pronunciation : Proust"ite
Part of Speech : n.
Etymology : [From the French chemist, J. L. Proust.] (Min.)
Definition : Defn: A sulphide of arsenic and silver of a beautiful cochineal-red color, occurring in rhombohedral crystals, and also massive; ruby silver.
Source : Webster's Unabridged Dictionary, 1913