mineral

Pyrite in Shale

Iron Disulfide (FeS2)

Hardness: 6-6.5 Mohs; Color: Pale brass-yellow to gold; Luster: Metallic; Crystal Structure: Isometric (cubic, pyritohedron); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

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

Identified April 7, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs; Color: Pale brass-yellow to gold; Luster: Metallic; Crystal Structure: Isometric (cubic, pyritohedron); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

Formation & geological history

Formed in sedimentary rock (likely shale) through the reduction of sulfates by organic matter in anaerobic conditions. Usually found in hydrothermal veins and sedimentary deposits.

Uses & applications

Primary source of sulfur and sulfuric acid; historically used to create sparks for firearms (wheel-locks); now popular for lapidary use and mineral collecting.

Geological facts

Commonly known as 'Fool's Gold' due to its resemblance to real gold. Unlike gold, which is soft and malleable, pyrite is brittle and will shatter or leave a black streak when tested.

Field identification & locations

Identify in the field by its brassy color, cubic crystal habit, and high hardness (it can scratch glass). It often occurs as clusters or fine-grained masses within darker sedimentary rocks.