sedimentary

Anthracite coal (likely)

Anthracite; carbon-rich coal composed mainly of maceral vitrinite, with variable mineral impurities

AI-generated identification · may be incorrect

Very dark gray to black, brittle, commonly submetallic to vitreous luster, and often shows conchoidal or irregular fracture. Hardness is about 2.5–3 on the Mohs scale; pieces may display layered or blocky texture and feel relatively lightweight.

Identified September 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Anthracite forms when buried bituminous coal undergoes intense heat and pressure during regional metamorphism, commonly associated with mountain building. It is usually Paleozoic in age, though age depends on the coal basin.

Uses & applications

Used as a high-carbon fuel, reducing agent, filtration medium, and historically in ironmaking; attractive lustrous pieces are collected but it is not generally a gemstone.

Geological facts

The specimen’s black, shiny, irregular fragments are consistent with anthracite, although the image alone cannot exclude bituminous coal, graphite-rich rock, or industrial carbon material.

Field identification & locations

Identify by black streak, low density, brittle fracture, and burning behavior; anthracite generally burns with little smoke and a hot blue flame. Common deposits occur in Pennsylvania, Wales, Ukraine, China, and Vietnam.