sedimentary
Coal (Bituminous Coal)
Caustobiolith / Sedimentary Rock
Hardness: 1.5 to 2.5 on the Mohs scale, Color: Dark black to dark brown, Luster: Dull to sub-vitreous or greasy, Crystal Structure: Amorphous (organic rock made mostly of carbon), Specific Gravity: 1.1 to 1.4
- Hardness
- 1
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Physical properties
Hardness: 1.5 to 2.5 on the Mohs scale, Color: Dark black to dark brown, Luster: Dull to sub-vitreous or greasy, Crystal Structure: Amorphous (organic rock made mostly of carbon), Specific Gravity: 1.1 to 1.4
Formation & geological history
Formed from the accumulation, burial, and compaction of plant debris (peat) in ancient swamps and wetlands over millions of years (primarily during the Carboniferous period), undergoing lithification under high pressure and temperature.
Uses & applications
Primarily used for electricity generation, steel production, and industrial manufacturing as a fossil fuel.
Geological facts
Coal beds often contain preserved fossilized plant fragments, bark, and spores from ancient forests that existed over 300 million years ago.
Field identification & locations
Can be identified by its dark black color, relatively low weight (light specific gravity), dark streak, and dirty or sooty feel when handled. Found worldwide in sedimentary basins.
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