metamorphic
Anthracite Coal
Anthracite
Hardness: 2.5-3.0; Color: Black or dark iron-gray; Luster: Sub-metallic to vitreous (glassy); Crystal structure: 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: 2.5-3.0; Color: Black or dark iron-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 under high pressure and temperature in folded mountain belts. It is typically found in geological formations dating back to the Carboniferous period.
Uses & applications
Primarily used for domestic and industrial heating due to its high carbon content and low impurity levels. Historically used in metallurgy and as a filtration medium for water treatment.
Geological facts
Anthracite is the highest rank of coal, containing 86% to 98% carbon. It burns with a short blue flame and produces very little smoke or soot compared to other coal types.
Field identification & locations
Identify in the field by its distinct glassy luster, clean touch (it does not soil fingers like softer coal), and tendency to break in curved, shell-like (conchoidal) patterns. Found in the Appalachian mountains of Pennsylvania, USA, as well as in South Wales and China.
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