mineral

Pyrite in Matrix (Commonly called Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5 (Mohs); Color: Brass-yellow; Luster: Metallic; Crystal Structure: Isometric (cubic/octahedral/pyritohedral); Cleavage: Indistinct; Specific Gravity: 4.8–5.0

Hardness: 6-6
Color: Brass-yellow
Luster: Metallic

Identified April 10, 2026More mineral →

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Physical properties

Hardness: 6-6.5 (Mohs); Color: Brass-yellow; Luster: Metallic; Crystal Structure: Isometric (cubic/octahedral/pyritohedral); Cleavage: Indistinct; Specific Gravity: 4.8–5.0

Formation & geological history

Formed in high and low-temperature hydrothermal veins, as an accessory mineral in igneous rocks, and in sedimentary rocks like shale and coal. It can form across various geological ages from Precambrian to recent epochs.

Uses & applications

Historically used for the production of sulfuric acid and sulfur. Today, it is primarily used as a minor ore of gold (as it often occurs with gold), in jewelry (as marcasite), and as a popular specimen for collectors.

Geological facts

Its name comes from the Greek 'pyritēs lithos', meaning 'stone which strikes fire', because it creates sparks when struck against steel. It is often mistaken for gold, but it is much harder and leaves a black or greenish-black streak, whereas gold leaves a yellow streak.

Field identification & locations

Identify in the field by its brassy color, cubic crystal habits, and high density. It is commonly found worldwide, notably in Spain, Peru, Italy, and the USA. Collectors should look for distinct geometric crystal shapes.

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