metamorphic
Anthracite Coal
Anthracite (Carbon-based solid)
Hardness: 2.5 - 3.0 on Mohs scale; Color: Black to steel grey; Luster: Sub-metallic to vitreous; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; 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 - 3.0 on Mohs scale; Color: Black to steel grey; Luster: Sub-metallic to vitreous; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific Gravity: 1.3 - 1.8.
Formation & geological history
Formed through the regional metamorphism of bituminous coal under intense pressure and heat within the Earth's crust. Most deposits date back to the Carboniferous period (approx. 300-360 million years ago) and are found in folded mountain belts.
Uses & applications
Predominantly used as a high-grade fuel for domestic and industrial heating due to its high carbon content and low impurities. It is also used in water filtration systems and as a carbon additive in steel manufacturing.
Geological facts
Anthracite is the highest rank of coal, containing 86% to 97% carbon. Unlike other coals, it burns with a clean blue flame and produces very little smoke or soot, making it the 'cleanest' burning fossil fuel.
Field identification & locations
Identify in the field by its high luster (looking almost like black glass), relative lightness compared to rocks of similar size, and the fact that it does not soil fingers like softer coals. Commonly found in Pennsylvania (USA), Wales, and parts of China.
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