FeS2pyriitti

FeS2pyriitti, more commonly known as pyrite or iron disulfide, is a mineral composed of iron and sulfur with the chemical formula FeS2. It is the most abundant sulfide mineral on Earth, found in a wide variety of geological environments, including sedimentary, metamorphic, and igneous rocks. Pyrite is characterized by its pale brass-yellow color and its metallic luster, which often leads to it being mistaken for gold, hence its nickname "fool's gold." The crystal structure of pyrite is cubic, and it commonly forms in well-defined cubic, octahedral, or pyritohedral crystals. It can also occur in massive, granular, or botryoidal forms.

Pyrite is relatively hard, with a Mohs hardness of 6 to 6.5, and brittle. It has a specific gravity of around 5.0. While often considered a subordinate mineral in many ore deposits, pyrite can be a significant source of sulfur and iron. It is also an important indicator mineral in certain geological settings, providing clues about the conditions under which the rocks formed. In some cases, pyrite can oxidize when exposed to air and water, forming sulfuric acid and iron oxides, a process that can contribute to acid mine drainage. Despite its common occurrence, pyrite has found some niche applications, such as in the production of sulfur dioxide for sulfuric acid manufacturing and historically as a source of ignition in flintlock mechanisms.