mineral

Pyrite in Gossan

Iron Sulfide (FeS2) in Ferruginous Rock

Hardness: 6-6.5 (Pyrite), 5-6 (Gossan host); Color: Brass-yellow metallic grains in reddish-brown earthy matrix; Luster: Metallic (pyrite) to dull (matrix); Structure: Isometric crystals (cubic or pentagonal dodecahedron) or granular; Cleavage: Indistinct; Specific Gravity: Approx. 4.88-5.02.

Hardness: 6-6
Color: Brass-yellow metallic grains in reddish-brown earthy matrix
Luster: Metallic (pyrite) to dull (matrix)

Identified June 9, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through hydrothermal precipitation of iron sulfides in mineral veins, followed by surface weathering (oxidation) that creates the iron-rich 'gossan' capping. It can occur in deposits spanning various geological ages, often associated with Precambrian to Mesozoic volcanic activity.

Uses & applications

Pyrite is used as an ore of sulfur and for the production of sulfuric acid; in the past, it was used as a sparking material. The gossan is a classic 'iron hat' indicator used by geologists to locate deeper base-metal or gold deposits.

Geological facts

Pyrite is famously known as 'Fool\'s Gold' because its color often confused prospectors. Historically, gossans were vital to miners because they pointed to valuable copper, lead, or zinc ores lying beneath the oxidized surface layer.

Field identification & locations

Look for the characteristic brassy-yellow metallic glint against a rusty, porous, or earthy reddish-brown rock. It is commonly found in mining districts globally, particularly in Spain, Peru, and the Western USA. To identify pyrite, scratch it against a porcelain streak plate; it will leave a greenish-black streak, unlike real gold which leaves a yellow streak.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

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

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic