sedimentary
Coal
Combustible sedimentary rock
Hardness: 1-2.5 on Mohs scale; Color: Black or dark brown; Luster: Dull to sub-metallic or vitreous; Structure: Amorphous, layered; Specific Gravity: 1.1-1.5
- Hardness
- 1-2
- Color
- Black or dark brown
- Luster
- Dull to sub-metallic or vitreous
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Physical properties
Hardness: 1-2.5 on Mohs scale; Color: Black or dark brown; Luster: Dull to sub-metallic or vitreous; Structure: Amorphous, layered; Specific Gravity: 1.1-1.5
Formation & geological history
Formed from the accumulation, burial, and compaction of plant debris in ancient swamps and wetlands over millions of years (Carboniferous period onward).
Uses & applications
Primary source of electricity generation, steel production, and industrial manufacturing.
Geological facts
Coal is often called 'buried sunshine' because it stores energy captured by plants from the sun hundreds of millions of years ago.
Field identification & locations
Identified by its dark color, relatively light weight, low hardness, and combustibility. Found extensively worldwide in sedimentary basins.
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