metamorphic
Anthracite Coal
Anthracite
Hardness: 2.5-3.0; Color: Jet black to dark gray with occasional iridescent luster; Luster: Sub-metallic to vitreous; Crystal Structure: Amorphous; Cleavage: Conchoidal fracture; Specific Gravity: 1.3-1.8
- Hardness
- 2
- Color
- Jet black to dark gray with occasional iridescent luster
- Luster
- Sub-metallic to vitreous
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Physical properties
Hardness: 2.5-3.0; Color: Jet black to dark gray with occasional iridescent luster; Luster: Sub-metallic to vitreous; Crystal Structure: Amorphous; Cleavage: Conchoidal fracture; Specific Gravity: 1.3-1.8
Formation & geological history
Formed through the high-grade metamorphism of sedimentary coal deposits (bituminous coal). It undergoes intense pressure and heat over millions of years, typically in fold mountain belts during orogenic events.
Uses & applications
Primarily used for domestic and industrial heating due to its high carbon content and low impurity level. Also used in water filtration and as a specialty fuel for blacksmithing.
Geological facts
Anthracite represents the highest rank of coal, containing 86% to 97% carbon. It is often referred to as 'hard coal' and burns with a short, blue, smokeless flame.
Field identification & locations
Identify by its high luster (shininess), lack of soot when touched compared to other coals, and its tendency to break into smooth, curved surfaces (conchoidal fracture). Commonly found in the Appalachian region of Pennsylvania.
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