metamorphic
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
Hardness: 2.5–3.0 on Mohs scale; Color: Black to steel-gray; Luster: Sub-metallic to vitreous (glassy); Structure: Amorphous/Non-crystalline; Fracture: Conchoidal; Specific Gravity: 1.3–1.8
- Hardness
- 2
- Color
- Black to steel-gray
- Luster
- Sub-metallic to vitreous (glassy)
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Physical properties
Hardness: 2.5–3.0 on Mohs scale; Color: Black to steel-gray; Luster: Sub-metallic to vitreous (glassy); Structure: Amorphous/Non-crystalline; Fracture: Conchoidal; Specific Gravity: 1.3–1.8
Formation & geological history
Formed through the localized metamorphism of bituminous coal under intense heat and pressure, typically during mountain-building events (orogeny). Most deposits are Carboniferous in age (approx. 300 million years old).
Uses & applications
Primary use is for domestic and industrial heating due to its high carbon content and low impurity levels. Historically used in metallurgy and water filtration; also collected as a specimen of high-grade coal.
Geological facts
Anthracite contains the highest carbon count of all coals (86% to 97%) and has the highest energy density. It burns with a short, blue, smokeless flame. It is often referred to as 'hard coal' or 'black gold' in Pennsylvania.
Field identification & locations
Identified in the field by its high luster, clean feel (it doesn't soil fingers like lower grade coal), and conchoidal fracture patterns. Found predominantly in the Appalachian region of the USA (Pennsylvania), China, and Russia.
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