mineral

Pyrite

Iron Disulfide (FeS2)

Hardness: 6-6.5 on the Mohs scale. Color: Pale brass-yellow with a metallic luster. Crystal structure: Isometric (often cubic or dodecahedral). Cleavage: Poor/Indistinct. Specific gravity: 4.9-5.2.

Hardness: 6-6
Color: Pale brass-yellow with a metallic luster

Identified February 5, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on the Mohs scale. Color: Pale brass-yellow with a metallic luster. Crystal structure: Isometric (often cubic or dodecahedral). Cleavage: Poor/Indistinct. Specific gravity: 4.9-5.2.

Formation & geological history

Forms in a wide range of geological environments, including hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic rocks, and in sedimentary rocks like shale and coal. It forms through the reaction of iron-bearing minerals with sulfide-rich fluids.

Uses & applications

Primarily used in the production of sulfuric acid and sulfur dioxide. It is historically significant as a source of ignition (fire-making). Today, it is popular in affordable jewelry (often incorrectly called 'marcasite') and as an entry-level collector's specimen.

Geological facts

Commonly known as 'Fool's Gold' because its color and metallic luster frequently confused prospectors. Unlike gold, pyrite is brittle and leaves a greenish-black streak, whereas gold is malleable and leaves a yellow streak.

Field identification & locations

Identify in the field by its brassy color, hardness (it will scratch glass, unlike gold), and characteristic cubic crystal shapes or striations. It is found globally, with notable deposits in Spain, Peru, Italy, and the USA. For collectors, it is a staple mineral due to its beautiful geometric crystal habits.