Anthracite Coal

Physical Properties

Hardness: 2.5-3.0 Mohs; Color: Black to steel-gray; Luster: Submetallic, vitreous, or brilliant; Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Specific Gravity: 1.3-1.8

Formation & Geological History

Formed through the low-grade metamorphism of bituminous coal under high pressure and temperature during mountain-building events (orogeny). Most deposits date from the Carboniferous Period (300-360 million years ago).

Uses & Applications

Primary use is for domestic and industrial heating as a smokeless fuel. Historically used in metallurgy and water filtration. Often collected as mineral specimens or used for carving decorative objects.

Geological Facts

Anthracite is the highest rank of coal, containing 86-97% carbon. It has the highest energy density of all coal ranks and burns with a short, blue, smokeless flame.

Field Identification & Locations

Identify by its shiny black surface, clean touch (it does not soil the hands like softer coal), and characteristic shell-like (conchoidal) fracture. Commonly found in folded mountain belts like the Appalachian Mountains in Pennsylvania.

Identified on: 5/2/2026

Mode: Standard