Fools Gold -

Pyrite forms in a wide variety of environments, including igneous, metamorphic, and sedimentary rocks. The Many Faces of Fool's Gold | American Scientist

Pyrite is an iron disulfide distinguished by its pale, brassy-yellow color and metallic luster. Despite its appearance, it is easily distinguished from real gold through several physical tests: Fools Gold

: It commonly forms perfect cubic, octahedral, or pyritohedral (12-faced) crystals. Pyrite forms in a wide variety of environments,