Description
Pyrite, also known as iron pyrite, is a mineral with the chemical formula FeS2, or iron disulfide. This mineral is an important source of iron and sulfur. It often crystallizes in well-formed, euhedral cubes with characteristic striations and a golden sheen. It is also known as "tinsel" or "fool's gold" because it was sometimes confused with gold. The term "cat's gold" is sometimes used incorrectly, but this actually refers to yellow mica or resin. Because pyrite is so common, it can create the illusion of great wealth, although it is not very valuable (although it can be sold). Pyrite is found in the company of other sulfur-bearing minerals and oxides, in quartz veins, sedimentary rocks in coal seams, and as a replacement mineral in fossils. Pyrite is a disulfide with sulfur pairs of (S2)2- and Fe2+ ions, surrounded by an octahedral structure in a t2g6 low-spin state. Because both ions have a closed configuration, it is a diamagnetic semiconductor. When pyrite weathers, iron (hydr)oxides are formed and sulfuric acid is released. This acid can react with other minerals, leading to the formation of minerals such as gypsum, alunite, and jarosite. A well-known source of pyrite is the island of Elba. The name "pyrite" derives from the ancient Indo-European word "pyr" (fire), similar to "pyrotechnics" (the art of fireworks) or the English word "pyre" (burning pyre), because one could create sparks by striking pyrite against flint or iron. Today, "flint" means something entirely different, namely a form of SiO2. Other names for pyrite include ferrous sulfide, ferric sulfide, and the less common terms ironblende and iron chert. In the past, pyrite was sometimes sold as imitation gold because of its golden sheen. However, this sheen changes when the surface is tilted, while with real gold, the sheen remains constant.
