sedimentary

Anthracite coal

Anthracite (high-rank coal; predominantly carbon, with minor mineral matter)

AI-generated identification · may be incorrect

Hardness about 2.5–3 Mohs; black to steel-gray, shiny or submettallic luster, brittle, irregular fracture, and generally noncrystalline or amorphous. The specimen’s glossy black, layered appearance is consistent with anthracite, though graphite or another carbon-rich rock is possible.

Identified September 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when bituminous coal was subjected to intense burial, heat, and pressure during regional metamorphism, commonly during mountain building. Its age depends on the coal basin, often Paleozoic (roughly 300–350 million years old).

Uses & applications

Burned as a relatively clean, high-carbon fuel; also used in water filtration and historically in metallurgy. Ordinary hand specimens have little commercial value.

Geological facts

Anthracite has the highest carbon content and greatest energy density of coal ranks, with low moisture and volatile content. It commonly burns with a short, blue flame and little smoke.

Field identification & locations

Identify by its hard, dense, bright black surface, conchoidal-to-irregular fracture, and lack of obvious glassy crystal faces; it should not leave a strongly metallic gray streak like graphite. Common in Pennsylvania, the Appalachian region, China, Russia, and parts of Europe.