metamorphic
Anthracite Coal
Anthracite
Hardness: 2.5-3.0 (Mohs scale). Color: Black to dark steel gray. Luster: Sub-metallic to vitreous (glassy). Structure: Amorphous (non-crystalline). Cleavage: Conchoidal fracture. Specific Gravity: 1.3-1.8.
- Hardness
- 2
- Color
- Black to dark steel gray
- Luster
- Sub-metallic to vitreous (glassy)
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Physical properties
Hardness: 2.5-3.0 (Mohs scale). Color: Black to dark steel gray. Luster: Sub-metallic to vitreous (glassy). Structure: Amorphous (non-crystalline). Cleavage: Conchoidal fracture. Specific Gravity: 1.3-1.8.
Formation & geological history
Formed through the regional metamorphism of bituminous coal under high pressure and temperature. It originates from organic plant matter buried in swamps over millions of years, primarily during the Carboniferous period.
Uses & applications
Primarily used for heating and power generation due to its high carbon content and low impurity levels. High-quality specimens are used in water filtration and as a pigment or for carving decorative items.
Geological facts
Anthracite is the highest rank of coal, containing 86% to 98% carbon. It burns with a blue flame and produces very little smoke or soot compared to lower-grade coals like lignite or bituminous.
Field identification & locations
Identify by its distinctive metallic sheen, hardness (it won't smudge fingers as easily as soot-like coal), and conchoidal fracture. Found in fold mountain belts such as the Appalachians in Pennsylvania, USA, and South Wales, UK.
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