The mineral pyrite (/ˈpaɪraɪt/ PY-ryte),[6] or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula FeS2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral.[7]
Pyrite cubic crystals on marl from Navajún, La Rioja, Spain (size: 95 by 78 millimetres [3.7 by 3.1 in], 512 grams [18.1 oz]; main crystal: 31 millimetres [1.2 in] on edge)
Pyrite's metallic luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of fool's gold. The color has also led to the nicknames brass, brazzle, and brazil, primarily used to refer to pyrite found in coal.[8][9]
https://en.wikipedia.org/wiki/Pyrite