Pyrite, commonly known as fool’s gold, may be found in a variety of environments along with igneous, metamorphic, and sedimentary rocks. For pyrite to form, sulfate compounds are reduced to sulfide by stripping away oxygen atoms. The sulfide atoms are then able to bind to iron, forming FeS₂ (pyrite). Commonly, pyrite is formed in sedimentary environments where certain bacterial processes result in the reduction of sulfate compounds. If iron is present, pyrite crystals may grow. The crystals form into cubic, octahedral, or pyritohedral shapes.