Pyrriitti

Pyrriitti, also known as iron pyrite or fool's gold, is an iron sulfide mineral with the chemical formula FeS2. It is one of the most common sulfide minerals on Earth and is found in a wide variety of geological environments, including sedimentary, metamorphic, and igneous rocks. Pyrriitti often occurs in association with other sulfide minerals like chalcopyrite and sphalerite, as well as with quartz and calcite.

Physically, pyrriitti is characterized by its pale brass-yellow color and its metallic luster. It is relatively hard, with a Mohs hardness of 6 to 6.5, and is brittle, meaning it can be easily broken. Pyrriitti often forms well-defined cubic or pyritohedral crystals, though it can also be found in massive or botryoidal forms. Its density is about 4.9 to 5.0 g/cm³.

Due to its appearance, pyrriitti has historically been mistaken for gold by prospectors, hence its nickname "fool's gold." Despite its deceptive appearance, pyrriitti has no significant economic value as a source of gold. However, it does have industrial uses. It is sometimes used in the production of sulfuric acid and sulfur dioxide, and has been explored as a potential material for solar cells, although its efficiency is limited. In mineral collecting, well-formed pyrriitti crystals are prized for their aesthetic appeal.