metamorphic
Anthracite
Anthracite (Carbon)
Hardness: 2.5–3.0 on Mohs scale; Color: Black to steel-gray; Luster: Sub-metallic to vitreous (glassy); Crystal structure: Amorphous; Cleavage: Conchoidal fracture; Specific gravity: 1.3–1.8
- Hardness
- 2
- Color
- Black to steel-gray
- Luster
- Sub-metallic to vitreous (glassy)
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Physical properties
Hardness: 2.5–3.0 on Mohs scale; Color: Black to steel-gray; Luster: Sub-metallic to vitreous (glassy); Crystal structure: Amorphous; Cleavage: Conchoidal fracture; Specific gravity: 1.3–1.8
Formation & geological history
Formed through the regional metamorphism of bituminous coal. Intense heat and pressure over millions of years (often Carboniferous period) drive off volatiles, leaving behind 86-98% pure carbon.
Uses & applications
Primarily used as a residential and industrial fuel due to its high energy density and low smoke. Also used in water filtration systems and as a reducing agent in smelting.
Geological facts
Anthracite is the highest grade of coal and contains the highest carbon count and fewest impurities. It burns with a short, blue flame and produces very little smoke or soot compared to softer coals.
Field identification & locations
Identify by its high luster (very shiny compared to other coal), lack of soot when handled, and the way it breaks into smooth, curved surfaces (conchoidal fracture). Commonly found in folded mountain belts like the Appalachians.
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