Pyrite (Fool's Gold): An Often-misunderstood Iron-Sulfide Mineral (RM-04)
Pyrite is often mistaken for gold because it is brassy yellow, although most gold is bright orange yellow. But color is about all pyrite and gold have in common. Pyrite is hard enough to scratch most metals and breaks up easily when struck with a hammer. Gold is soft and malleable and may be rolled into thin sheets. Pyrite occurs in geometric crystal forms, such as cubes, octahedra, and pyritohedra, but can be massive or graular and occasionally fibrous. Gold can also form in geometric crystals but is mostly roundish globs, wiry masses, or flakes.

Pyrite, the most common sulfide mineral, is found in almost any kind of rock in Indiana. It has been mined as a source of sulfur for sulfuric acid, fertilizers, etc. Today, most sulfur comes from native sulfur deposits of the Gulf Coast and from sulfurous crude oils. When coal containing pyrite is burned, sulfur dioxide, a serious pollutant in the atmosphere, is formed.

Our Hoosier State Beneath Us: Rocks and Minerals


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