mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

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

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

Identified March 30, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in high and low temperature hydrothermal veins, as an accessory mineral in igneous rocks, and in sedimentary rocks like coal and shale through the reduction of sulfur. Found in rocks of various geological ages from Precambrian to recent.

Uses & applications

Historically used as a source of sulfur for sulfuric acid production; currently used in jewelry (as marcasite), in car batteries, and as an industrial catalyst. Widely sought after by mineral collectors.

Geological facts

Commonly nicknamed 'Fool's Gold' because its color and metallic luster often led prospectors to mistake it for gold. It is unique among sulfide minerals because it can spark when struck against steel, which led to its name derived from the Greek word 'pyr' (fire).

Field identification & locations

Identify in the field by its brittle nature and greenish-black streak (real gold is soft and leaves a yellow streak). Commonly found in Spain (Rio Tinto), Peru (Huanzala), and across the USA (Colorado and Illinois). Collectors should look for distinct geometric cubic shapes.