mineral

Pyrite in Matrix (often with Chalcopyrite)

Iron Sulfide (FeS2) / Copper Iron Sulfide (CuFeS2)

Hardness: 6-6.5; Color: Brass-yellow to greenish-gold; Luster: Metallic; Crystal Structure: Isometric (cubic/octahedral); Cleavage: Indistinct; Specific Gravity: 4.8–5.1.

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

Identified April 12, 2026More mineral →

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Physical properties

Hardness: 6-6.5; Color: Brass-yellow to greenish-gold; Luster: Metallic; Crystal Structure: Isometric (cubic/octahedral); Cleavage: Indistinct; Specific Gravity: 4.8–5.1.

Formation & geological history

Formed in hydrothermal veins, as an accessory mineral in igneous rocks, and by contact metamorphism. It can also form in sedimentary environments under reducing conditions.

Uses & applications

Primary source of sulfur and sulfuric acid in the past; occasionally an ore of copper or iron. It is popular among collectors and used in costume jewelry.

Geological facts

Commonly known as 'Fool's Gold' because its color and weight can trick beginner prospectors into thinking it is gold. It can contain trace amounts of actual gold within its structure.

Field identification & locations

Identify by its 'brassy' metallic luster, greenish-black streak (real gold has a yellow streak), and its brittleness (gold is malleable). Common in mining districts worldwide.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral