metamorphic
Anthracite Coal
Anthracite (Carbon Content: 86%–98%)
Hardness: 2.5–3.0 Mohs; Color: Jet black to dark gray, often with a sub-metallic luster; Luster: Vitreous to sub-metallic; Crystal Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 1.3–1.8
- Hardness
- 2
- Color
- Jet black to dark gray, often with a sub-metallic luster
- Luster
- Vitreous to sub-metallic
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Physical properties
Hardness: 2.5–3.0 Mohs; Color: Jet black to dark gray, often with a sub-metallic luster; Luster: Vitreous to sub-metallic; Crystal Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 1.3–1.8
Formation & geological history
Formed through the regional metamorphism of sedimentary bituminous coal under high pressure and temperature. It is the highest grade of coal, primarily dating from the Carboniferous Period (300-360 million years ago).
Uses & applications
Used primarily for residential and commercial heating due to its high density and clean burn. Historically significant in the iron and steel industry; also used in water filtration systems and as a semi-precious material for jewelry or carving.
Geological facts
Anthracite is often called 'hard coal' or 'black diamond.' It contains the highest energy density of all coal types and burns with a short, blue, smokeless flame. It accounts for only about 1% of the world's total coal reserves.
Field identification & locations
Identify in the field by its high luster, lack of soot when handled, and the way it breaks into smooth, curved surfaces (conchoidal fracture). Commonly found in the Appalachian region of Pennsylvania (USA), Wales (UK), and parts of China.
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