a bronze-colored, typically magnetic, hexagonal mineral, FeS, usually found with pentlandite; iron sulfide
See pyrrhotite in American Heritage Dictionary 4
(pĭrˈə-tītˌ) also pyr·rho·tine(-tīnˌ)
noun
A brownish-bronze iron sulfide mineral, FeS, characterized by weak magnetic properties and used as an iron ore and in the manufacture of sulfuric acid. Also called magnetic pyrites.