mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5 (Mohs scale), Color: Pale brass-yellow, Luster: Metallic, Crystal structure: Isometric (often cubic or octahedral), Cleavage: Indistinct, Specific Gravity: 4.9-5.2

Hardness: 6-6

Identified April 10, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6-6.5 (Mohs scale), Color: Pale brass-yellow, Luster: Metallic, Crystal structure: Isometric (often cubic or octahedral), Cleavage: Indistinct, Specific Gravity: 4.9-5.2

Formation & geological history

Forms in a wide variety of geological environments including sedimentary deposits, hydrothermal veins, and as an accessory mineral in igneous rocks. It can form across various geological ages.

Uses & applications

Historically used as a source of sulfur and sulfuric acid. Today it is primarily used as a collector specimen, in jewelry (often called 'marcasite'), and sometimes in the production of lithium-ion batteries.

Geological facts

It earned the nickname 'Fool's Gold' because its color and metallic luster often led novice prospectors to confuse it with gold. However, it is much harder and more brittle than real gold.

Field identification & locations

Identified in the field by its brassy color, hardness (it will scratch glass, gold will not), and its greenish-black streak when rubbed on a porcelain plate. Found globally, especially in Peru, Spain, and the USA.