Pyrite

Pyrite, also known as iron pyrite, is an iron sulfide and constitutes the most abundant sulfide mineral. Its metallic sheen and pale brass-yellow color often lead to a deceptive resemblance to gold, earning it the widely recognized moniker of "fool's gold."

Typically discovered in conjunction with other sulfides or oxides within quartz veins, sedimentary rock, and metamorphic rock, pyrite is also present in coal beds and occasionally serves as a replacement mineral in fossils. Despite its colloquial name suggesting otherwise, pyrite can occasionally coexist with small amounts of actual gold.