metamorphic
Anthracite Coal
Anthracite
Hardness: 2.5-3.0 (Mohs); Color: Black to dark steel-gray; Luster: Sub-metallic to vitreous (glassy); Structure: Amorphous/foliated texture; Cleavage: Conchoidal fracture; Specific Gravity: 1.3-1.8
- Hardness
- 2
- Color
- Black to dark steel-gray
- Luster
- Sub-metallic to vitreous (glassy)
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Physical properties
Hardness: 2.5-3.0 (Mohs); Color: Black to dark steel-gray; Luster: Sub-metallic to vitreous (glassy); Structure: Amorphous/foliated texture; Cleavage: Conchoidal fracture; Specific Gravity: 1.3-1.8
Formation & geological history
Formed through the prograde metamorphism of bituminous coal. It involves the application of intense heat and pressure over millions of years, typically in areas of mountain-building (orogeny), dating from the Carboniferous period approx. 300 million years ago.
Uses & applications
Primarily used as a high-grade fuel for residential and industrial heating due to its high carbon content and low impurities. Also used in water filtration systems and as a source for activated carbon.
Geological facts
Anthracite is the highest rank of coal, containing 86%-97% carbon. It has the highest energy density of all coal types and burns with a short, blue, smokeless flame.
Field identification & locations
Field identification: Look for its distinct metallic luster and 'clean' feel compared to other coals (it doesn't soil fingers easily). Found in folded mountain belts like the Appalachian Mountains in Pennsylvania, USA.
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