mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

AI-generated identification · may be incorrect

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden-yellow; 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-yellow
Luster: Metallic

Identified March 15, 2026More mineral →

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Physical properties

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

Formation & geological history

Forms in diverse environments including magmatic segregation, hydrothermal veins, and as an authigenic mineral in sedimentary rocks. It is found in rocks of all geological ages, from Precambrian to recent.

Uses & applications

A major source of sulfur and sulfuric acid; historically used as a spark generator in early firearms (whelock); used in jewelry (marcasite jewelry) and as popular specimen for collectors.

Geological facts

Commonly nicknamed 'Fool's Gold' because its color and metallic luster often led novice prospectors to mistake it for real gold. However, it is much harder than gold and brittle rather than malleable.

Field identification & locations

Identify in the field by its brassy color, hardness (it can scratch glass), and its greenish-black streak. It is common worldwide, with significant deposits in Spain, Peru, Italy, and the USA (Arizona, Pennsylvania).