metamorphic
Anthracite Coal
Anthracite
Hardness: 2.5–3 on Mohs scale; Color: Black to steel-grey; Luster: Sub-metallic to vitreous; Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Specific Gravity: 1.3–1.8
- Hardness
- 2
- Color
- Black to steel-grey
- Luster
- Sub-metallic to vitreous
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Physical properties
Hardness: 2.5–3 on Mohs scale; Color: Black to steel-grey; Luster: Sub-metallic to vitreous; Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Specific Gravity: 1.3–1.8
Formation & geological history
Formed through the intense metamorphism of peat and lower-grade coal layers under high heat and pressure, typically during mountain-building events (orogeny). Most is 300-360 million years old (Carboniferous period).
Uses & applications
Primarily used for heating and industrial filtration. Historically used for domestic fuel and steam generation. Higher grades are used in water purification and as a recarburizer in steel production.
Geological facts
Anthracite is the highest grade of coal and contains the highest percentage of fixed carbon (86-97%). Unlike lower-grade coal, it burns with a blue, smokeless flame and is very clean to the touch.
Field identification & locations
Identify in the field by its high luster (shiny appearance), black streak, and conchoidal (shell-like) fracture. It is much harder and cleaner than bituminous coal. Commonly found in Pennsylvania, USA, and parts of the UK and China.
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