mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal Structure: Isometric (often cubic or octahedral); Cleavage: Indistinct; Specific Gravity: 4.9-5.2.

Hardness: 6-6
Color: Pale brass-yellow to golden
Luster: Metallic

Identified March 28, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal Structure: Isometric (often cubic or octahedral); Cleavage: Indistinct; Specific Gravity: 4.9-5.2.

Formation & geological history

Forms in a wide variety of geological settings, including hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic rocks, and in sedimentary rocks like shale and coal. It can form across all geological ages.

Uses & applications

Historically used as a source of sulfur and sulfuric acid. Today, it is primarily used in jewelry (as 'marcasite'), as a collector's specimen, and occasionally in the production of lithium batteries; however, it is no longer a primary iron ore.

Geological facts

Widely known as 'Fool's Gold' due to its resemblance to precious metal. In ancient times, it was used to create sparks for fire-starting. Some specimens contain small amounts of actual gold hidden within the crystal matrix.

Field identification & locations

Identify in the field by its brittle nature (it crushes to powder, whereas gold flattens) and its greenish-black streak when rubbed on a porcelain plate. Common locations include Peru, Spain, and the USA (Colorado/Arizona).