sedimentary

Coal

Bituminous Coal (organic sedimentary rock)

Hardness: 0.5–2.5 on Mohs scale; Color: Black to brownish-black; Luster: Vitreous to dull; Structure: Massive or layered; Cleavage: None (conchoidal fracture); Specific Gravity: 1.1–1.5.

Hardness: 0
Color: Black to brownish-black
Luster: Vitreous to dull

Identified July 13, 2026More sedimentary →

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Physical properties

Hardness: 0.5–2.5 on Mohs scale; Color: Black to brownish-black; Luster: Vitreous to dull; Structure: Massive or layered; Cleavage: None (conchoidal fracture); Specific Gravity: 1.1–1.5.

Formation & geological history

Formed from the accumulation of plant remains in swampy environments (peat) that have been subjected to heat and pressure over millions of years, typically during the Carboniferous period (300-360 million years ago).

Uses & applications

Primarily used as a fuel source for electric power generation and industrial heat. It is also a key ingredient in the production of steel (coke) and various chemical processes.

Geological facts

Coal is often called 'buried sunshine' because it stores energy from prehistoric plants. It is the most abundant fossil fuel on Earth, though its use is declining due to environmental impacts.

Field identification & locations

Identify by its black color, relatively light weight compared to silicate rocks, and its tendency to leave a black smudge on hands. Commonly found in sedimentary basins and near old railway tracks where it may have fallen from transport.