sedimentary
Bituminous Coal (with Anthracite or Vitrinite inclusion)
Organic-rich Sedimentary Rock (Carboniferous classification)
Hardness: 0.5 to 2.5 on Mohs scale; Color: Black, brownish-black with earthy brown exterior; Luster: Vitreous (glassy) to dull; Crystal structure: Amorphous/Organic; Specific gravity: 1.1–1.4.
- Hardness
- 0
- Color
- Black, brownish-black with earthy brown exterior
- Luster
- Vitreous (glassy) to dull
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Physical properties
Hardness: 0.5 to 2.5 on Mohs scale; Color: Black, brownish-black with earthy brown exterior; Luster: Vitreous (glassy) to dull; Crystal structure: Amorphous/Organic; Specific gravity: 1.1–1.4.
Formation & geological history
Formed from the high-pressure burial and heating of anaerobic peat (plant matter) over millions of years, typically during the Carboniferous period (300-360 million years ago); found in deltaic and swamp-forest environments.
Uses & applications
Primary source for electricity generation and heating; also used in the production of coke for steel manufacturing and high-strength carbon fibers.
Geological facts
This specimen appears to show a cross-section of 'bright' vitrinite coal within a more weathered or silty matrix. Coal is technically a 'biolith', a rock made almost entirely of organic material rather than minerals.
Field identification & locations
Identify in the field by its light weight (low density), black streak when rubbed on porcelain, and tendency to fracture into blocky or conchoidal shapes. Commonly found in the Appalachian Basin (USA), China, and Australia.
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