sedimentary
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
Mohs hardness: 2.5-3.0; Color: Black to dark steel gray; Luster: Sub-metallic to brilliant vitreous; Crystal structure: Amorphous; Cleavage: None (conchoidal fracture); Specific gravity: 1.3-1.8.
- Hardness
- 2
- Color
- Black to dark steel gray
- Luster
- Sub-metallic to brilliant vitreous
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Physical properties
Mohs hardness: 2.5-3.0; Color: Black to dark steel gray; Luster: Sub-metallic to brilliant vitreous; Crystal structure: Amorphous; Cleavage: None (conchoidal fracture); Specific gravity: 1.3-1.8.
Formation & geological history
Formed through the extreme compression and heating of organic peat and bituminous coal over hundreds of millions of years, typically during mountain-building events (orogeny) such as those in the Carboniferous period.
Uses & applications
Primarily used for high-efficiency domestic heating, metallurgical processes, and filtration media. High-quality pieces are sometimes used for carving decorative objects.
Geological facts
Anthracite has the highest carbon count of all coal types (86% to 98%) and the fewest impurities. It burns with a short, blue, smokeless flame.
Field identification & locations
Identify by its characteristic shiny luster, smooth conchoidal fracture, and the fact that it does not soil fingers like softer coals. Found in folded mountain belts like the Appalachians of Pennsylvania, USA.
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