sedimentary

Anthracite coal

Anthracite; predominantly carbon (C), with minor mineral impurities

AI-generated identification · may be incorrect

Very dark gray to black, semi-metallic to vitreous luster, hard (Mohs 2.5–3), dense, and brittle; commonly shows irregular or subconchoidal fracture and faint layering. The specimen’s black, compact, lustrous appearance is consistent with coal, though identification from a photograph is limited.

Identified September 13, 2026More sedimentary →

Explore Anthracite coal in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Anthracite forms when buried plant-rich sediment (peat) is subjected to intense heat and pressure during regional metamorphism, typically in Paleozoic coal basins. It is technically a metamorphosed sedimentary material rather than a true igneous or metamorphic rock classification in many field guides.

Uses & applications

Used primarily as a clean-burning solid fuel, carbon source, and filtration medium; attractive pieces may be collected, but it is not normally used as a gemstone or building stone.

Geological facts

It has the highest carbon content and greatest heating value of coal types, generally about 86–97% carbon, and burns with a short blue flame and little smoke.

Field identification & locations

Identify by its hard, shiny black surface, low density relative to many ores, black streak, and ability to burn; graphite is softer and leaves a stronger mark. Common in Pennsylvania, Wales, China, Russia, and Vietnam.