About
Pyrite occurs in numerous shapes and habits. The smaller crystal aggregates may give off a beautiful glistening effect in light, and the larger crystals may be perfectly formed, including fascinating cubes, penetration twins, and other interesting crystal forms. The perfect cubes of Pyrite embedded in a matrix from the famous Spanish mines are especially treasured among collectors. Many of these specimens have fallen out of the matrix and have been repaired by having them glued back into the matrix.
Pyrite has the same chemical formula as the rarer mineral Marcasite, but it crystallizes in a different crystal system, thereby classifying it as a separate mineral species. Aggregates of iron sulfide (FeS2) where the crystal structure cannot be determined without complex analyzing material may be wrongly labeled by dealers. Some Pyrite specimens are labeled as Marcasite, and some Marcasite specimens as Pyrite.
For additional information, see the gemstone section on Pyrite.
Crystal Forms & Aggregates
Other ID Marks
Striking Features
Environment
Varieties
✓ common · ✗ uncommon
- Cathedral Pyrite— Pyrite with etched, gothiclike markings
- Dollar— Flat disc of radiating Pyrite or Marcasite.
- Pyrite Cube— Large, undistorted, cubic shaped Pyrite.
- Pyrite Sun— Synonym of Pyrite Dollar.
- Pyritohedron— Pyrite with with a pyritohedral shape.
- Rainbow Pyrite— Iridescent Pyrite from the Volga River of Russia. Rainbow Pyrite is usually in spherical concretions that contain internal shrinkage fractures, and the iridescence is caused by oxidation.
Polymorphs
Uses
Noteworthy Localities
Enormous deposits of Pyrite in the form of small crystal clusters exist in the Huaron Mining District in Peru. Other outstanding Peruvian localities are the Quiruvilca Mine, La Libertad; and the Huanzala, Huánuco. Most of the amateur collector Pyrite comes from the Peruvian locations in abundance, though fine outstanding crystals have also come from there as well.
In the Ampliación a Victoria Mine, Navajún, La Rioja, (formerly Logroño), Spain, large perfect cubic Pyrite crystals, are mined in abundance. They are frequently embedded in a light brown matrix, and are occasionally inter-penetrating. Excellent pyritohedral crystals occur in Rio Marina on the island of Elba, Italy, which is a classic locality. A locality which has recently brought interestingly shaped, complex Pyrite crystals to the market is the Merelani Hills, Arusha, Tanzania.
In the U.S., fine Pyrite localities abound. In Park City, Bingham Co., Utah, large, well shaped pyritohedrons and cubes were once found. The Bingham Canyon Mine, Salt Lake Co., Utah is also a classic occurrence, where few of the excellent Pyrites from the mine are saved from the mining crusher. Large, intergrown cubes, many times partially octahedral, occurred in abundance at Leadville, Lake Co., Colorado. Pyrite "dollars" are well-known from Sparta, Randolph Co., Illinois. The French Creek Mine in Chester Co., Pennsylvania is famous for the octahedral crystals that occur there, although most are distorted. Ross Co., Ohio, produces rounded tubular growths of Pyrite, some reaching several feet in size, as well as growths of spiky, pineapple-like crystals.
Common Mineral Associations
Distinguishing Similar Minerals
Cobaltite - Lacks yellow color of Pyrite, lower hardness.
Marcasite - Crystallizes in different crystal system.
Pyrrhotite - Lower hardness, darker color, different crystal form.
Small, gold colored, massive or flaky Pyrite may be confused with Gold, but is easily distinguished by Pyrite's black streak and Gold's yellow streak (and by Gold's low hardness and lack of brittleness.)
Photos
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