mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal System: Isometric/Cubic; Cleavage: Poor/Indistinct; Specific Gravity: 4.9-5.2

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

Identified May 21, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal System: Isometric/Cubic; Cleavage: Poor/Indistinct; Specific Gravity: 4.9-5.2

Formation & geological history

Forms in a variety of geological settings including hydrothermal veins, by segregation from magmas, and as an authigenic mineral in sedimentary rocks. It is found in rocks of all ages from the Archean to the Holocene.

Uses & applications

Historically used as a source of sulfur and sulfuric acid. Today it is used in jewelry (as marcasite), in radio receivers (crystal detectors), and sometimes as an ore for gold which is often found in association with it.

Geological facts

Pyrite is nicknamed 'Fool's Gold' because its color and high density lead many amateur prospectors to mistake it for real gold. Unlike gold, it is brittle and will shatter rather than flatten when struck.

Field identification & locations

Identify in the field by its cubic crystal habit, metallic luster, and its dark green to black streak on a porcelain plate (gold has a yellow streak). Commonly found worldwide, especially in Peru, Spain, and the USA.