ˌärs( ə )nō, ärˌsenō+ noun
( -s )
Etymology: arsen- + pyrite
: a mineral FeAsS consisting of a hard tin-white or grayish iron sulfarsenide occurring in prismatic orthorhombic crystals or in masses or grains, found chiefly in crystalline rocks, and constituting the principal ore of arsenic (hardness 5.5-6, specific gravity 5.9-6.2) — called also arsenical pyrites, mispickel