metamorphic
Anthracite Coal
Anthracite (high-rank coal)
Hardness: 2.5-3.0 Mohs; Color: Black to deep iron-black; Luster: Submetallic, vitreous to semi-metallic; Crystal Structure: Amorphous; Cleavage: Conchoidal fracture; Specific gravity: 1.3-1.8
- Hardness
- 2
- Color
- Black to deep iron-black
- Luster
- Submetallic, vitreous to semi-metallic
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Physical properties
Hardness: 2.5-3.0 Mohs; Color: Black to deep iron-black; Luster: Submetallic, vitreous to semi-metallic; Crystal Structure: Amorphous; Cleavage: Conchoidal fracture; Specific gravity: 1.3-1.8
Formation & geological history
Formed through the regional metamorphism of bituminous coal in sedimentary basins. Most deposits date to the Carboniferous period (300-360 million years ago) and were created by high pressure and heat during mountain-building events.
Uses & applications
Primarily used for domestic and industrial heating due to its high carbon content and low smoke. Historically used in metallurgy and as a filtration medium for water purification. Occasionally used for carving decorative objects.
Geological facts
Anthracite is the highest rank of coal, containing between 86% and 97% carbon. It has the highest energy density of all coal types and burns with a short, blue, smokeless flame. It accounts for only about 1% of global coal reserves.
Field identification & locations
Identify in the field by its high luster, lack of soot when touched, and conchoidal (glass-like) fracture patterns. It is much harder and cleaner than bituminous coal. Major deposits are found in Eastern Pennsylvania (USA), Wales, and China.
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