sedimentary
Coal
Coal (Combustible sedimentary rock)
AI-generated identification · may be incorrectHardness: 1-2.5 on the Mohs scale, Color: Black or brownish-black, Luster: Dull to sub-metallic or vitreous, Structure: Amorphous with distinct layering (banded or unbanded), Specific Gravity: 1.1-1.5
- Hardness
- 1-2
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Physical properties
Hardness: 1-2.5 on the Mohs scale, Color: Black or brownish-black, Luster: Dull to sub-metallic or vitreous, Structure: Amorphous with distinct layering (banded or unbanded), Specific Gravity: 1.1-1.5
Formation & geological history
Formed from the accumulation, burial, and compaction of plant debris (peat) in ancient wetland forests and swamps over millions of years, primarily during the Carboniferous and Permian periods.
Uses & applications
Historically and currently used primarily as a solid fossil fuel for electricity generation, steel production, and industrial heat.
Geological facts
Coal beds often preserve exquisite fossilized impressions of ancient ferns and tree barks, providing a crucial window into Earth's prehistoric ecosystems.
Field identification & locations
Easily identified by its light weight, dark black color, black streak, and tendency to soil the fingers when handled. Found worldwide in sedimentary basins.
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