sedimentary

Coal (Anthracite/Bituminous)

Carbo fossilium (primarily Carbon)

AI-generated identification · may be incorrect

Hardness: 0.5–2.5 (Mohs scale); Color: Black to dark brown; Luster: Dull to sub-metallic/vitreous; Texture: Brittle, often with a blocky or conchoidal fracture; Density: 1.1–1.5 g/cm³.

Hardness: 0
Color: Black to dark brown
Luster: Dull to sub-metallic/vitreous

Identified June 28, 2026More sedimentary →

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Physical properties

Hardness: 0.5–2.5 (Mohs scale); Color: Black to dark brown; Luster: Dull to sub-metallic/vitreous; Texture: Brittle, often with a blocky or conchoidal fracture; Density: 1.1–1.5 g/cm³.

Formation & geological history

Formed from the accumulation of plant remains in swampy environments (peat) that undergo biochemical and physical changes over millions of years through burial, heat, and pressure (lithification). Most major deposits date to the Carboniferous period (300-360 million years ago).

Uses & applications

Primarily used as a fuel for electricity generation and industrial heating; used in the production of steel (coke) and as a raw material for various chemicals and synthetic fibers.

Geological facts

Coal is often referred to as 'buried sunshine' because it contains the solar energy captured by plants millions of years ago. It is the largest source of energy for the generation of electricity worldwide.

Field identification & locations

Identify in the field by its characteristic black color, lightweight feel compared to silicate rocks, and its ability to leave a black smudge on hands or a streak plate. It is commonly found in sedimentary basins and near mining regions in areas like Appalachia or the Ruhr Valley.