Pirite

Pirite, also known as pyrite, is an iron sulfide mineral with the chemical formula FeS2. It is one of the most common sulfide minerals and is widely distributed in sedimentary, metamorphic, and igneous rocks. It has a metallic luster and a brass-yellow color that resembles gold, earning the nickname fool's gold. Crystals are typically cubic or pyritohedral, and it forms in the isometric crystal system. The Mohs hardness is about 6–6.5, and its streak is greenish-black to brownish-black.

Occurrence and formation: Pyrite forms in a variety of geological environments, including hydrothermal veins, sedimentary diagenesis, and metamorphic rocks. It commonly occurs with quartz, chalcopyrite, marcasite, and other sulfides, as disseminations, nodules, or euhedral crystals. Large, well-formed crystals are particularly valued by collectors. It is abundant in many ore deposits and can form framboidal aggregates in coal beds.

Uses and economic importance: Pyrite is not a major source of iron but has historically provided sulfur for chemical processes, especially for the production of sulfuric acid through roasting to release sulfur dioxide. It has also been used as a gemstone and decorative mineral in jewelry and carvings, particularly when it forms attractive crystals. The mineral is often collected and studied in geology and mineralogy.

Safety and environmental considerations: When exposed to air and moisture, pyrite can oxidize to form iron oxides and sulfuric acid, contributing to acid mine drainage and environmental degradation around mines. Fine pyrite dust can be an inhalation hazard.