mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6–6.5 Mohs scale. Color: Pale brass-yellow with occasional tarnish. Luster: Strong metallic. Crystal Structure: Isometric (often cubic or pyritohedral crystals). Cleavage: Poor/Indistinct. Specific Gravity: 4.9–5.2.

Hardness: 6–6
Color: Pale brass-yellow with occasional tarnish
Luster: Strong metallic

Identified March 14, 2026More mineral →

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Physical properties

Formation & geological history

Formed in a variety of geological settings including hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic rocks, and as a sedimentary replacement mineral (often replacing fossils or organic matter).

Uses & applications

Historically used as a source of sulfur and for making sulfuric acid; used in jewelry as 'marcasite'; used in the production of lithium batteries; frequently kept as a decorative specimen for collectors.

Geological facts

Commonly known as 'Fool's Gold' due to its metallic luster and yellow hue. It can be distinguished from gold by its brittleness, hardness, and the black/greenish-black streak it leaves on a streak plate.

Field identification & locations

Identify in the field by its brassy color, cubic habit, and inability to be scratched by a copper penny or steel knife. Found globally, with notable deposits in Spain, Peru, and the USA. Collectors look for sharp, mirror-like crystal faces.