Ce*rar"gy*rite (s&esl;*rär"j&ybreve;*rīt), n. [Gr. ke`ras horn + 'a`rgyros silver.] (Min.) 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).