mineral

Pyrite in Matrix

Iron Sulfide (FeS2)

Hardness: 6-6.5; Color: Brass-yellow (Pyrite), dark gray/black (Matrix); Luster: Metallic; Crystal Structure: Isometric; Cleavage: Indistinct; Specific Gravity: 4.9-5.2

Hardness: 6-6
Color: Brass-yellow (Pyrite), dark gray/black (Matrix)
Luster: Metallic

Identified June 11, 2026More mineral →

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Physical properties

Hardness: 6-6.5; Color: Brass-yellow (Pyrite), dark gray/black (Matrix); Luster: Metallic; Crystal Structure: Isometric; Cleavage: Indistinct; Specific Gravity: 4.9-5.2

Formation & geological history

Formed in high and low temperature hydrothermal veins, by magmatic segregation, or as an accessory mineral in igneous and sedimentary rocks. Often found in association with quartz and sulfide minerals.

Uses & applications

Major ore for sulfur and sulfuric acid production; historically used in ignition for firearms; ornamental use in inexpensive jewelry (often called 'marcasite'); popular collector specimens.

Geological facts

Commonly known as 'Fool's Gold' because its color and weight lead inexperienced prospectors to believe they have found gold. It is the most common sulfide mineral.

Field identification & locations

Identify in the field by its brassy color, cubic crystal habit, and greenish-black streak when rubbed on a porcelain plate. Common in Peru, Spain, Italy, and the USA.