metamorphic
Anthracite Coal
Anthracite
Hardness: 2.5-3.0 (Mohs); Color: Iron-black to sub-metallic gray; Luster: Metallic to sub-metallic; Crystal Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Specific Gravity: 1.3-1.7
- Hardness
- 2
- Color
- Iron-black to sub-metallic gray
- Luster
- Metallic to sub-metallic
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Physical properties
Hardness: 2.5-3.0 (Mohs); Color: Iron-black to sub-metallic gray; Luster: Metallic to sub-metallic; Crystal Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Specific Gravity: 1.3-1.7
Formation & geological history
Formed through the regional metamorphism of bituminous coal in areas of high heat and tectonic pressure. It represents the highest grade of coalification, where organic matter is compressed over millions of years (often Carboniferous period).
Uses & applications
Historically used as a clean-burning fuel for residential heating and steam generation. Currently used in industrial filtration (water treatment) and as a carbon additive in the steel industry.
Geological facts
Anthracite contains the highest percentage of fixed carbon (86% to 98%) and the lowest amount of volatile matter of all coal types. It burns with a short, blue, smokeless flame.
Field identification & locations
Identify by its shiny black surface and conchoidal (shell-like) fracture. Unlike other coals, it does not soil fingers when handled. Commonly found in Pennsylvania, USA, the UK, and parts of China.
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