pyrite (n.) Look up pyrite at Dictionary.com
"metallic iron disulfide, fool's gold," 1550s, from Old French pyrite (12c.), from Latin pyrites, from Greek pyrites lithos "stone of fire, flint" (so called because it glitters), from pyrites "of or in fire," from pyr (genitive pyros) "fire" (see fire (n.)). Related: Pyritic.