mineral

Auriferous Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5 Mohs. Color: Brass-yellow to grayish-gold. Luster: Metallic. Crystal Structure: Isometric (cubic). Cleavage: Poor/Indistinct. Specific Gravity: 4.9-5.2.

Hardness: 6-6
Color: Brass-yellow to grayish-gold
Luster: Metallic

Identified June 18, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs. Color: Brass-yellow to grayish-gold. Luster: Metallic. Crystal Structure: Isometric (cubic). Cleavage: Poor/Indistinct. Specific Gravity: 4.9-5.2.

Formation & geological history

Forms in hydrothermal veins, contact metamorphic deposits, and as an accessory mineral in igneous and sedimentary rocks. Common in the Huachuca Mountains and surrounding Cochise County (Arizona) in Laramide-era sulfide deposits.

Uses & applications

Historically used as an ore of sulfur and sulfuric acid. Occasionally used as a minor gemstone or for specimen collecting. Sometimes indicates the proximity of gold in quartz veins.

Geological facts

Known as 'Fool's Gold' because its color and luster are similar to real gold, though it is much harder and more brittle. The name comes from the Greek 'pyros' meaning fire, because it sparks when struck by metal.

Field identification & locations

Identify by its brittle nature (it crushes to powder), greenish-black streak, and high hardness (it will scratch glass). Common in Southern Arizona mining districts like Bisbee and Tombstone.