FeS2 – pyrite – is an iron sulfide. Pyrite has a metallic sheen and pale brass-yellow hue. Its strong resemblance to gold led to its nickname of "fool's gold.” Pyrite forms intricate cubic, octahedral, dodecahedral, and other crystals. Its magnetic properties are due to impurities caused by magnetic elements (Mn, Ni, Co). Pyrite gives off sparks on impact, which led to its past use in firearms. Pyrite is a raw material in the production of sulfuric acid and sulfur. Pyrite is also used to make jewelry.