mineral

Pyrite (Fool's Gold) Ore

Iron Disulfide (FeS2)

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

Hardness: 6-6
Color: Pale brass-yellow to gray-black
Luster: Metallic

Identified April 9, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in hydrothermal veins, by magmatic segregation, or as an authigenic mineral in sedimentary rocks. It occurs across various geological eras where sulfur and iron are present in oxygen-poor environments.

Uses & applications

Major source of sulfur for sulfuric acid production; historically a source of iron. Used as an ornamental stone and in jewelry (marcasite jewelry). Significant in mineral collecting and used in early radio receivers.

Geological facts

Known as 'Fool's Gold' because its color and weight can confuse prospectors, though it's much harder and more brittle than real gold. It can create sparks when struck against steel.

Field identification & locations

Identify in the field by its metallic luster, yellowish-gray color, and streak test (it leaves a green-black streak, unlike gold which leaves a yellow streak). Commonly found in Spain, Italy, and the USA.