mineral

Pyrite

Iron Sulfide (FeS2)

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

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

Identified July 11, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in a variety of geological settings including hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic rocks, and in sedimentary environments like coal beds and shale through the action of bacteria in anaerobic conditions.

Uses & applications

Historically a source of sulfur and sulfuric acid. Today, it is primarily used as a collector specimen, in jewelry (often incorrectly called 'marcasite'), and sometimes as an ore for gold as they are frequently found together.

Geological facts

Commonly known as 'Fool's Gold' due to its resemblance to real gold. Unlike gold, it is brittle and leaves a greenish-black streak when rubbed on a porcelain plate, whereas gold is malleable and leaves a yellow streak.

Field identification & locations

Identify by its metallic luster, golden hue, and characteristic crystal shapes. It is found globally, with famous deposits in Spain, Italy, and the USA. Collectors should look for sharp cubic forms and avoid exposure to high humidity, as some specimens can oxidize and decay over time.