What is Pyrite?

Mary McMahon
Mary McMahon

Pyrite, also called Fool's Gold, is a distinctly golden colored mineral that contains a mixture of iron and sulfur. It can be found all over the world, and the sulfur it contains was historically extracted for a variety of industrial processes. The stone sometimes contains trace amounts of gold, but not usually enough to make it valuable, and it is also sometimes used in jewelry, under the label of marcasite. The origin of the name for the stone is Greek; pyrite means “fire stone” and is a reference to its ancient use to start fires by striking it against another rock to create sparks.

Sulfur is found in pyrite.
Sulfur is found in pyrite.

This mineral has a metallic sheen and a striking crystalline structure. Some pyrites come in other shapes, such as rounds, but the most common form resembles a jumbled pile of crystals with thin lines or striations along their faces. Pyrite is very brittle, and shatters easily along the joins of the crystals. Unlike gold, it is not workable. Iron composes approximately 46% of the mineral, with the remainder made up by sulfur and trace impurities such as gold, nickel, arsenic, and copper.

Pyrite has a few interesting properties: in addition to creating sparks, the mineral can conduct a weak current. Although it is mainly an ornamental curiosity, it is sometimes mined commercially. Industrially, pyrite can be chemically treated to extract sulfur and trace minerals like gold and copper. This chemical treatment is highly polluting, so most mining companies with more ready access to the individual minerals will avoid using it.

Other minerals such as quartz, galena, fluorite, calcite, and gold are often found in close proximity to pyrite, which is sometimes used as an indicator stone for these other minerals. It is extremely common in deposits of sedimentary rocks, ore deposits, and around hydrothermal deposits, where the heat and pressure could combine the sulfur and iron. Although pyrite is common all over the world, it is particularly widespread in the American Midwest, South Africa, Eastern Europe, and Peru.

Most rock shops carry small pieces of pyrite and some jewelry made from it, and larger chunks of the mineral are sometimes available as well. It can make an intriguing paperweight, or a fun gift for a treasure obsessed child. Many rock collectors also enjoy collecting particularly striking specimens with well formed crystals or interesting shapes.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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