Rock Identifier
Pyrite in Quartz (Iron Sulfide (FeS2) in Silicon Dioxide (SiO2)) — Mineral
Mineral

Pyrite in Quartz

Iron Sulfide (FeS2) in Silicon Dioxide (SiO2)

Hardness: 6-6.5 (Pyrite), 7 (Quartz); Color: Brass-yellow metallic grains in tan/white matrix; Luster: Metallic (gold-like) and vitreous; Crystal system: Cubic/Isometric (Pyrite); Specific gravity: 4.9-5.2.

Hardness
6-6
Color
Brass-yellow metallic grains in tan/white matrix
Luster
Metallic (gold-like) and vitreous
Identified More mineral

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Physical properties

Hardness: 6-6.5 (Pyrite), 7 (Quartz); Color: Brass-yellow metallic grains in tan/white matrix; Luster: Metallic (gold-like) and vitreous; Crystal system: Cubic/Isometric (Pyrite); Specific gravity: 4.9-5.2.

Formation & geological history

Formed in hydrothermal veins and through metamorphic processes where sulfur-rich fluids crystallize in fractures within host rocks, often associated with gold-bearing ores. Common in ancient mountain-building environments.

Uses & applications

Source of sulfur and sulfuric acid in industry; indicator mineral for gold prospecting; popular for student education 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 leaves a greenish-black streak when rubbed on a porcelain plate.

Field identification & locations

Identify in the field by checking for metallic luster and cubic crystal habits; check hardness with a steel knife (pyrite is harder than gold). Frequently found in mining districts and sedimentary rock outcrops near metallic deposits.