mineral

Pyrite (Fools Gold)

Iron Sulfide (FeS2)

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

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

Identified April 10, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow; 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, by magmatic segregation in igneous rocks, and as a diagenetic mineral in sedimentary rocks like shale. Found across all geological ages.

Uses & applications

Historically used as a source of sulfur and in the production of sulfuric acid. Used sometimes in jewelry (referred to as 'marcasite' in the trade) and widely collected by mineral enthusiasts.

Geological facts

Known as 'Fools Gold' because its color and luster frequently misled prospectors. It is the most common sulfide mineral and can generate sparks when struck against steel or flint.

Field identification & locations

Identify by its brittle nature (gold is soft/malleable), its greenish-black streak (gold has a yellow streak), and its cubic crystal habit. Commonly found in metamorphic rocks, quartz veins, and coal crystals.