metamorphic
Anthracite Coal
Anthracite
Hardness: 2.5-3.0 Mohs; Color: Iron-black to submetallic lead-gray; Luster: Submetallic, vitreous; Crystal Structure: Amorphous; Cleavage: Conchoidal fracture; Specific gravity: 1.3–1.4
- Hardness
- 2
- Color
- Iron-black to submetallic lead-gray
- Luster
- Submetallic, vitreous
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Physical properties
Hardness: 2.5-3.0 Mohs; Color: Iron-black to submetallic lead-gray; Luster: Submetallic, vitreous; Crystal Structure: Amorphous; Cleavage: Conchoidal fracture; Specific gravity: 1.3–1.4
Formation & geological history
Formed through the burial and intense metamorphism of organic plant matter under high pressure and temperature over millions of years (often Carboniferous period). It is the highest rank of coal.
Uses & applications
Primarily used as a high-quality fuel for domestic and industrial heating, in the production of steel (metallurgy), and water filtration media.
Geological facts
Anthracite is sometimes referred to as 'hard coal' or 'black diamond'. It has the highest carbon content (86% to 98%) and the fewest impurities of all coal types.
Field identification & locations
Identify in the field by its high luster, lack of sooty residue compared to bituminous coal, and its tendency to break with smooth, curved (conchoidal) surfaces. Commonly found in folded mountain belts like the Appalachians.
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