sedimentary
Coal
Combustible Sedimentary Rock
AI-generated identification · may be incorrectHardness 1-2.5 on Mohs scale, black or brownish-black color, dull to sub-metallic luster, amorphous crystal structure, uneven fracture, and low specific gravity (1.3-1.4).
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Physical properties
Hardness 1-2.5 on Mohs scale, black or brownish-black color, dull to sub-metallic luster, amorphous crystal structure, uneven fracture, and low specific gravity (1.3-1.4).
Formation & geological history
Formed from compressed plant debris accumulated in ancient swamps over millions of years, primarily during the Carboniferous period.
Uses & applications
Extensively used for electricity generation, industrial steel production, and previously for home heating.
Geological facts
Coal represents ancient solar energy stored as carbon and contains fossilized plant structures visible under microscopic analysis.
Field identification & locations
Identified by its dark color, relative lightness, and soil-black streak; commonly found in sedimentary basins worldwide.
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