sedimentary

Anthracite coal

Anthracite; predominantly carbon (C), with minor macerals, ash, sulfur, and trace minerals

AI-generated identification · may be incorrect

Black to steel-gray, typically submetallic to vitreous luster, dense and relatively hard (Mohs about 2–3), with irregular to subconchoidal fracture and little visible crystal structure. The specimen appears massive and brittle, though lighting limits certainty; the small silvery object may be separate metal or mineral.

Identified September 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Anthracite forms when buried plant-rich peat is progressively metamorphosed under high heat and pressure, producing very high fixed-carbon content. It is mainly Paleozoic in age, especially from Carboniferous coal basins.

Uses & applications

Used as a high-grade solid fuel, in water filtration, and historically for ironmaking. Attractive, lustrous pieces are occasionally collected, but it is not generally a gemstone.

Geological facts

Anthracite burns with a short blue flame, little smoke, and high heat compared with bituminous coal. It commonly shows conchoidal fracture and may leave a black streak.

Field identification & locations

Identify it by its hard, shiny black appearance, low density relative to many ores, black streak, and lack of obvious plant layering; it should not fizz in dilute acid. Common localities include Pennsylvania, Wales, Vietnam, China, and parts of Russia.