metamorphic
Anthracite Coal
Anthracite (Carbon)
Hardness: 2.5-3.0 Mohs; Color: Jet black to dark grey; Luster: Sub-metallic to vitreous (glassy); Crystal Structure: Amorphous; Cleavage: None (conchoidal fracture); Specific Gravity: 1.3-1.8
- Hardness
- 2
- Color
- Jet black to dark grey
- Luster
- Sub-metallic to vitreous (glassy)
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Physical properties
Hardness: 2.5-3.0 Mohs; Color: Jet black to dark grey; Luster: Sub-metallic to vitreous (glassy); Crystal Structure: Amorphous; Cleavage: None (conchoidal fracture); Specific Gravity: 1.3-1.8
Formation & geological history
Formed through the low-grade metamorphism of bituminous coal. It is the result of intense pressure and heat in the Earth's crust, typically associated with mountain-building events (orogenies) such as the Alleghanian orogeny (approx. 300 million years ago).
Uses & applications
Primarily used for high-grade domestic heating due to its high energy density and low smoke. It is also used in metallurgy for smelting, as a filtration medium in water treatment, and occasionally for carving decorative ornaments.
Geological facts
Anthracite is the highest rank of coal, containing 86% to 98% carbon. Unlike other coals, it burns with a short, blue, smokeless flame. It is often referred to as 'hard coal' or 'black diamond.'
Field identification & locations
Identify by its light weight, shiny glass-like luster, and lack of soot when handled compared to soft coal. Found commonly in the Appalachian Mountains of Pennsylvania, USA, as well as in Wales and parts of China. Collect for its brilliant shine and geological rarity compared to other coal types.
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