sedimentary
Anthracite Coal
Anthracite (Metamorphosed Carbon)
Hardness: 2.5-3 (Mohs scale); Color: Black or brownish-black; Luster: Submetallic to vitreous (glassy); Crystal Structure: Amorphous; Cleavage: Conchoidal fracture; Specific Gravity: 1.3-1.8.
- Hardness
- 2
- Color
- Black or brownish-black
- Luster
- Submetallic to vitreous (glassy)
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Physical properties
Hardness: 2.5-3 (Mohs scale); Color: Black or brownish-black; Luster: Submetallic to vitreous (glassy); Crystal Structure: Amorphous; Cleavage: Conchoidal fracture; Specific Gravity: 1.3-1.8.
Formation & geological history
Formed from the accumulation of plant matter in swampy environments (peat) that underwent high pressure and heat over millions of years (carbonization), typically during the Carboniferous period. Although it is a coal, it is often considered the highest grade of coal due to low volitiles and high carbon content.
Uses & applications
Primarily used as a fuel for domestic heating and industrial processes (smelting iron) due to its high energy density and clean-burning properties. Also used in water filtration systems.
Geological facts
Anthracite is the most metamorphosed type of coal, containing between 86% and 97% carbon. It burns with a short, blue, smokeless flame. It accounts for only about 1% of global coal reserves.
Field identification & locations
Identified in the field by its dark black color, shiny/metallic luster, and the fact that it does not soil fingers like softer coals (bituminous). Found in folded mountain belts like the Ridge-and-Valley province of the Appalachians.
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