mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5 Mohs. Color: Pale brass-yellow. Luster: Metallic. Crystal structure: Isometric. Cleavage: Indistinct. Specific gravity: 4.9–5.2. Streak: Greenish-black to brownish-black.

Hardness: 6-6
Color: Pale brass-yellow
Luster: Metallic

Identified April 10, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs. Color: Pale brass-yellow. Luster: Metallic. Crystal structure: Isometric. Cleavage: Indistinct. Specific gravity: 4.9–5.2. Streak: Greenish-black to brownish-black.

Formation & geological history

Formed in high and low-temperature hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic rocks, and in sedimentary rocks such as shale, coal, and limestone. It can form in various geological ages ranging from the Precambrian to the present.

Uses & applications

Major ore for the production of sulfur and sulfuric acid. Used as a semiconductor material in solar panels. Often collected as mineral specimens and used in jewelry (labeled as 'marcasite' in the trade).

Geological facts

Known as 'Fool's Gold' because its color often confused prospectors. Unlike gold, it is brittle and will shatter if struck, and it produces a spark when struck against steel. It is the most common sulfide mineral.

Field identification & locations

Identify by its metallic luster and brassy color. Check streak color (black/greenish) to distinguish from gold (yellow streak). Look for cubic or octahedral crystal habits. Commonly found worldwide in mining districts, especially in Peru, Spain, and the USA.