Pyrite

Pyrite is a brass-yellow mineral with a bright metallic luster. It has a chemical composition of iron sulfide and is the most common sulfide mineral. It forms at high and low temperatures and occurs, usually in small quantities, in igneous, metamorphic, and sedimentary rocks worldwide. Pyrite is so common that many geologists would consider it to be a ubiquitous mineral. The name "pyrite" is after the Greek "pyr" meaning "fire" given because pyrite can be used to create the sparks needed for starting a fire if it is struck against metal or another hard material. Pyrite has a nickname that has become famous - "Fool's Gold." The mineral's gold color, metallic luster, and high specific gravity often cause it to be mistaken for gold by inexperienced prospectors. However, pyrite is often associated with gold. The two minerals often form together, and in some deposits pyrite contains enough included gold to warrant mining. https://www.mindat.org/min-3314.html https://geology.com/minerals/pyrite.shtml