sedimentary

Likely anthracite coal fragments

Anthracite; predominantly carbon (C), with minor mineral ash and sulfides

AI-generated identification · may be incorrect

Black to steel-gray, brittle, commonly angular fragments with bright submetallic to vitreous surfaces; Mohs hardness about 2–3, noncrystalline/amorphous carbon, and no cleavage. The silvery patches may be pyrite or reflective fracture surfaces.

Identified August 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Anthracite forms when bituminous coal is subjected to intense burial, heat, and pressure during regional metamorphism, typically over hundreds of millions of years. Common source beds are Carboniferous–Permian coal basins.

Uses & applications

Used as a high-carbon fuel, smokeless heating coal, filtration media, and occasionally as a mineral specimen; it has little jewelry value.

Geological facts

Anthracite contains the highest fixed-carbon content of coal, generally about 86–97%, and burns with a short blue flame and little smoke. It can leave a black streak and may contain shiny pyrite-bearing zones.

Field identification & locations

Identify it by its hard, glassy black appearance, low soot, and conchoidal or irregular fracture; a streak test and lack of metallic malleability help distinguish it from metal ore. Common in Pennsylvania, Wales, China, Russia, and Vietnam.