metamorphic
Anthracite Coal
Anthracite (Carbon-rich metamorphic rock)
Hardness: 2.5–3 on Mohs scale; Color: Black or dark iron-gray; Luster: Sub-metallic to vitreous (glassy); Structure: Massive/amorphous; Cleavage: Conchoidal fracture; Specific Gravity: 1.3–1.8
- Hardness
- 2
- Color
- Black or dark iron-gray
- Luster
- Sub-metallic to vitreous (glassy)
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Physical properties
Hardness: 2.5–3 on Mohs scale; Color: Black or dark iron-gray; Luster: Sub-metallic to vitreous (glassy); Structure: Massive/amorphous; Cleavage: Conchoidal fracture; Specific Gravity: 1.3–1.8
Formation & geological history
Formed through the low-grade metamorphism of bituminous coal under intense heat and pressure. Most high-quality deposits originated during the Carboniferous period (300-360 million years ago) from compressed plant matter in swamp environments.
Uses & applications
Primarily used as a high-grade fuel for domestic and industrial heating due to its high carbon content and low smoke. Also used in water filtration systems and as a source of carbon for steel production.
Geological facts
Anthracite has the highest carbon count (86%-98%) and the fewest impurities of all coal types. It is often referred to as 'hard coal' and burns with a short, blue, smokeless flame.
Field identification & locations
Identify by its shiny, black, glass-like appearance and the fact that it does not soil fingers when touched (unlike bituminous coal). It is commonly found in the Appalachian region of Pennsylvania, UK, China, and Vietnam.
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