Cerargyrite
Pronunciation : Ce*rar"gy*rite
Part of Speech : n.
Etymology : [Gr. (Min.)
Definition : Defn: Native silver chloride, a mineral of a white to pale yellow or gray color, darkening on exposure to the light. It may be cut by a knife, like lead or horn (hence called horn silver).
Source : Webster's Unabridged Dictionary, 1913