sedimentary

Pyrite in Shale

Iron Sulfide (FeS2) in Argillaceous Shale

AI-generated identification · may be incorrect

Hardness: 6-6.5 (Pyrite) / 3 (Shale); Color: Brass-yellow (Pyrite) on Grey/Black (Shale); Luster: Metallic; Crystal Structure: Isometric/Cubic crystals embedded in a fine-grained matrix; Streak: Greenish-black

Hardness: 6-6
Color: Brass-yellow (Pyrite) on Grey/Black (Shale)
Luster: Metallic

Identified April 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in low-oxygen (anoxic) sedimentary environments where organic matter and sulfates are present. Microbiological activity reduces sulfate to sulfide, which reacts with iron to form pyrite crystals within the settling mud that later lithifies into shale.

Uses & applications

Pyrite is used as a source of sulfur and in the production of sulfuric acid. In this specific form, it is primarily a geological specimen for education or collecting.

Geological facts

Pyrite is known as 'Fool\'s Gold' because of its metallic luster and yellow hue. When found in shale, it often indicates the presence of organic-rich prehistoric mudflats or deep-ocean floors.

Field identification & locations

Identify by looking for metallic, cubic glints against a dull, grey, flaky rock. Use a hand lens to see the sharp crystal edges. Commonly found in sedimentary basins and coal beds.