sedimentary

Bituminous coal

Coal, predominantly carbon with macerals and minor clay/pyrite minerals

AI-generated identification · may be incorrect

Black to brownish-black, generally dull to vitreous luster, organic sedimentary material with no consistent crystal structure; Mohs hardness about 2–3, brittle, low density, and commonly leaves a black streak. The pieces appear irregular and glossy, consistent with coal, though anthracite is another possibility.

Identified August 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and heated swamp vegetation in sedimentary basins, typically over millions to hundreds of millions of years; bituminous coal commonly develops during burial and low-grade metamorphism of peat.

Uses & applications

Used primarily as fuel and in electricity generation; selected bituminous coal is converted to coke for steelmaking. Specimens have modest educational and collector interest.

Geological facts

Coal is combustible and may show bright vitrain bands alongside dull fusain or clarain. Anthracite is harder, denser, and more uniformly shiny than bituminous coal.

Field identification & locations

Common in coal-bearing strata worldwide, including the Appalachian, Illinois, Ruhr, and Shanxi basins. Identify by very low density, black streak, organic layering, and burning behavior; avoid testing unknown samples by flame indoors.