Pyriet

Pyriet, the Dutch name for pyrite, is an iron sulfide mineral with the chemical formula FeS2. It is one of the most common sulfide minerals and occurs in a wide range of geological settings, including hydrothermal veins, sedimentary rocks, and igneous rocks. Pyrite is large in-scale familiar in many deposits and can form in craftsman-like cubes or more complex crystals, though it also occurs as massive, granular material.

Physically, pyrite has a brass-yellow color with a metallic luster and a greenish-black to brownish-black streak. It crystallizes in the isometric system and frequently forms cube-shaped crystals or pyritohedra, but it also occurs in massive or granular forms. Its hardness on the Mohs scale is 6 to 6.5, and it has a density of about 5.0 g/cm3. The mineral is brittle and tends to fracture conchoidally. Pyrite can tarnish to a darker surface upon exposure to air and moisture.

Occurrence and associations: Pyrite is widely distributed and occurs in a variety of environments, often alongside other sulfide minerals such as marcasite, chalcopyrite, and sphalerite. It is common in quartz veins, coal beds, sedimentary rocks, and metamorphic terrains. Major producers include several countries with rich sulfide-bearing formations.

Significance: Pyrite has been used as a source of sulfur and, historically, indirectly for sulfuric acid production. The name derives from the Greek pyr for fire, because striking pyrite with steel can produce sparks. It is also known as fool’s gold due to its superficial resemblance to native gold. Environmentally, pyrite oxidation can contribute to acid mine drainage, releasing sulfuric acid and iron compounds when exposed to air and water. It remains a popular specimen among mineral collectors.