Pyrite (Iron Pyrite) "Fools Gold"

Pyrite is the classic "Fool's Gold". There are other shiny brassy yellow minerals, but pyrite is by far the most common and the most often mistaken for gold. Whether it is the golden look or something else, pyrite is a favorite among rock collectors. It can have a beautiful luster and interesting crystals. It is so common in the earth's crust that it is found in almost every possible environment, hence it has a vast number of forms and varieties.

Unlike gold, which is prized because of its color, brightness, workability, and rareness, Pyrite is not a metal, but rather, a sulfide made up of iron and sulfur. Pyrite is much harder and more brittle, and it tarnishes to a dark brown. Fool's Gold is very common, and this has led to many people thinking they had discovered real gold over the years. Pyrite forms when hydrogen sulfide combines with iron. These common elements often fuse and are carried by heated fluids to cracks in native rocks where pyrite is deposited. It is attractive, and many museums keep specimens of Pyrite for display or educational purposes.

Bravoite is the name given to a nickel-rich iron sulfide. It is closely related to pyrite but contains up to 20% nickel. Some mineral books treat it as a variety of pyrite. Pyrite is a polymorph of Marcasite, which means that it has the same chemistry, FeS2, as Marcasite; but a different structure and therefore different symmetry and crystal shapes. Pyrite is difficult to distinguish from Marcasite when a lack of clear indicators exists.