sedimentary

Anthracite Coal

Anthracite

Hardness: 2.0-2.5 Mohs; Color: Black or dark grey; Luster: Submetallic, vitreous (glassy); Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Density: 1.3-1.7 g/cm3

Hardness: 2
Color: Black or dark grey
Luster: Submetallic, vitreous (glassy)

Identified July 9, 2026More sedimentary →

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Physical properties

Hardness: 2.0-2.5 Mohs; Color: Black or dark grey; Luster: Submetallic, vitreous (glassy); Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Density: 1.3-1.7 g/cm3

Formation & geological history

Formed from the remains of ancient plant matter that underwent intense heat and pressure over millions of years (Carboniferous period). It is the highest grade of coal and is often considered to be on the border of metamorphic rock due to the pressure required to form it.

Uses & applications

Primarily used as a high-quality fuel for domestic heating and industrial power generation. Historically used in smelting iron. Used as a filter medium in water treatment due to its purity.

Geological facts

Anthracite contains the highest carbon content of all coals (86-97%) and has the fewest impurities. It burns with a short blue flame and produces very little smoke or soot compared to bituminous coal.

Field identification & locations

Identified in the field by its high luster (shinier than typical coal), deep black color, and the way it breaks into smooth, curved surfaces (conchoidal fracture). It is much cleaner to handle than other types of coal. Common in the Appalachian mountains of Pennsylvania.