mineral side rock

Pyrite Cubes in Matrix

Iron Disulfide (FeS2) in Host Matrix

AI-generated identification · may be incorrect

Hardness: 6-6.5 (Pyrite). Color: Metallic brass-yellow (cube) in a white or tan matrix. Luster: Metallic. Crystal Structure: Isometric/Cubic. Cleavage: Indistinct. Specific Gravity: 4.9-5.2.

Hardness: 6-6
Color: Metallic brass-yellow (cube) in a white or tan matrix
Luster: Metallic

Identified July 4, 2026More mineral side rock →

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Physical properties

Hardness: 6-6.5 (Pyrite). Color: Metallic brass-yellow (cube) in a white or tan matrix. Luster: Metallic. Crystal Structure: Isometric/Cubic. Cleavage: Indistinct. Specific Gravity: 4.9-5.2.

Formation & geological history

Forms in a variety of geological environments, including hydrothermal veins, sedimentary rocks (shale, limestone), and metamorphic rocks. This specific specimen appears to be a cube emerging from a sedimentary or clay-rich host matrix.

Uses & applications

Major ore of sulfur (historically), used in jewelry (as marcasite), and highly popular as a collector's mineral. Occasionally used in the production of sulfuric acid.

Geological facts

Pyrite is famously known as 'Fool's Gold' because its color and high specific gravity can lead novice prospectors to mistake it for gold. However, pyrite is much harder and more brittle than real gold.

Field identification & locations

Identified by its distinctive perfect cubic shape and metallic 'brassy' luster. Can be found globally, with famous cubic specimens coming from Navajun, Spain. To identify in the field, look for the 'iron' smell when struck and its inability to be scratched by a copper penny.