sedimentary

Coal

Anthracite or Bituminous Coal

Hardness: 0.5-2.5 (Mohs scale), Color: Black to brownish-black, Luster: Dull to sub-metallic, Structure: Amorphous/Organic, Specific Gravity: 1.1–1.5. Low density and relatively lightweight.

Hardness: 0

Identified July 8, 2026More sedimentary →

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Physical properties

Hardness: 0.5-2.5 (Mohs scale), Color: Black to brownish-black, Luster: Dull to sub-metallic, Structure: Amorphous/Organic, Specific Gravity: 1.1–1.5. Low density and relatively lightweight.

Formation & geological history

Formed from the accumulation of plant remains in swampy environments that are buried and subjected to heat and pressure over millions of years (Carboniferous period).

Uses & applications

Primarily used as a fuel source for electricity generation and industrial heating; also used in steel production (as coke) and chemical manufacturing.

Geological facts

Coal is often referred to as 'buried sunshine' because it stores 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 by its black color, light weight, and tendency to leave a black smudge on fingers or porcelain. Found in sedimentary basins and coal seams. Collectors look for plant fossils often embedded within shale layers near coal.