metamorphic
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
Hardness: 2.5–3.0 on Mohs scale; Color: Black to dark iron-gray; Luster: Sub-metallic to vitreous (glassy); Crystal structure: Amorphous; Cleavage: Conchoidal fracture; Specific gravity: 1.3–1.4
- Hardness
- 2
- Color
- Black to dark iron-gray
- Luster
- Sub-metallic to vitreous (glassy)
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Physical properties
Hardness: 2.5–3.0 on Mohs scale; Color: Black to dark iron-gray; Luster: Sub-metallic to vitreous (glassy); Crystal structure: Amorphous; Cleavage: Conchoidal fracture; Specific gravity: 1.3–1.4
Formation & geological history
Formed from the accumulation of plant matter that has undergone extreme heat and pressure over millions of years, typically during mountain-building events (orogeny). It has the highest carbon content (86-97%) of all coal types.
Uses & applications
Primarily used for high-grade domestic and industrial heating, water filtration media, and as a reducing agent in metal smelting due to its high energy density and low impurity levels.
Geological facts
Anthracite is known as 'hard coal' and represents the highest metamorphic grade of coal. It burns with a short, blue, smokeless flame. The most significant deposits were formed during the Carboniferous period, roughly 300 to 360 million years ago.
Field identification & locations
Identify in the field by its distinct shiny, metallic appearance and clean handle (it doesn't leave black soot on hands like bituminous coal). Commonly found in the Appalachian region of Pennsylvania, USA, and parts of Wales and China.
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