mineral

Pyrite-rich Gossan

Iron Sulfide (FeS2) in Ore Matrix

Hardness: 6-6.5 (for Pyrite); Color: Brassy yellow with reddish-brown oxidation crust; Luster: Metallic to earthy; Crystal structure: Isometric; Cleavage: Indistinct

Hardness: 6-6
Color: Brassy yellow with reddish-brown oxidation crust
Luster: Metallic to earthy

Identified May 24, 2026More mineral →

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Physical properties

Hardness: 6-6.5 (for Pyrite); Color: Brassy yellow with reddish-brown oxidation crust; Luster: Metallic to earthy; Crystal structure: Isometric; Cleavage: Indistinct

Formation & geological history

Formed through hydrothermal deposition or sedimentary precipitation in anoxic environments. This specimen appears to be from an oxidation zone (gossan) where iron-bearing minerals have weathered to iron oxides like limonite or goethite.

Uses & applications

Primarily used as an ore of sulfur and for the production of sulfuric acid; occasionally used in low-cost jewelry (as 'marcasite') and as a common mineral for collectors.

Geological facts

Commonly known as 'Fool's Gold' because of its metallic luster and brassy hue which leads novice prospectors to mistake it for real gold. It can sometimes contain trace amounts of actual gold or cobalt.

Field identification & locations

Identify by its brassy color when fresh, its green-black streak on a porcelain plate, and its cubic crystal habit if present. It is found globally in many different geological environments.