metamorphic
Anthracite Coal
Anthracite (Carbon C)
Hardness: 2.5-3.0; Color: Jet black to dark grey; Luster: Sub-metallic to vitreous (glassy); Crystal structure: Amorphous; Fracture: Conchoidal; Specific Gravity: 1.3-1.7
- Hardness
- 2
- Color
- Jet black to dark grey
- Luster
- Sub-metallic to vitreous (glassy)
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Physical properties
Hardness: 2.5-3.0; Color: Jet black to dark grey; Luster: Sub-metallic to vitreous (glassy); Crystal structure: Amorphous; Fracture: Conchoidal; Specific Gravity: 1.3-1.7
Formation & geological history
Formed through the regional metamorphism of bituminous coal in sedimentary basins under intense pressure and heat, typically associated with mountain-building events (orogenies) such as the Alleghenian orogeny.
Uses & applications
Primarily used as a high-grade fuel for domestic heating and industrial processes (metallurgy) due to its high carbon content and low impurity levels. Also used for water filtration and as a specialty carving material.
Geological facts
Anthracite contains the highest percentage of fixed carbon (86%-97%) of all coal types. It burns with a short, blue, smokeless flame. Despite being classified as a coal, its formation process under metamorphic conditions makes it technically a metamorphic rock.
Field identification & locations
Identify by its characteristic glassy luster and conchoidal fracture which prevents it from staining fingers like lower-grade coals. Commonly found in the Appalachian region of Pennsylvania, USA, as well as parts of South Wales and China.
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