sedimentary
Coal
Bituminous or sub-bituminous coal (carbonaceous rock)
AI-generated identification · may be incorrectHardness: 2.5-3 on the Mohs scale, Color: Black to dark brown, Luster: Dull to sub-vitreous, Crystal structure: Amorphous, Specific Gravity: 1.1-1.5
- Hardness
- 2
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Physical properties
Hardness: 2.5-3 on the Mohs scale, Color: Black to dark brown, Luster: Dull to sub-vitreous, Crystal structure: Amorphous, Specific Gravity: 1.1-1.5
Formation & geological history
Formed from compressed plant remains in ancient wetland forests (swamps/peat bogs) over millions of years (primarily Carboniferous and Permian periods).
Uses & applications
Historically used as a primary fossil fuel for electricity generation, heating, and steel production.
Geological facts
Coal deposits record major climate and botanical shifts in Earth's history, preserving fossilized remains of ancient ferns, giant club mosses, and horsetails.
Field identification & locations
Lightweight relative to typical rocks, black and sooty to the touch, burns readily. Found in sedimentary basins worldwide.
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