How do anthracite’s appearance and physical properties differ from those of other coal ranks?

Anthracite represents the highest rank of coal, distinguished from lower-rank coals like lignite and bituminous coal by its unique physical and chemical profile.12

Appearance and Texture

Anthracite is characterized by a black to steel-gray color and a brilliant, almost metallic luster. Unlike many other coal types, such as fusain—which is soft, fibrous, and soils the hands—anthracite is clean to the touch. It is hard and brittle, breaking with a distinct conchoidal fracture that produces sharp, shell-like fragments.13

Physical and Chemical Properties

The primary differences between anthracite and other ranks stem from the degree of coalification, which is driven by intense heat and geological deformation.12

• Composition: Anthracite contains the highest concentration of fixed carbon (86 percent or greater) and the lowest amount of volatile matter (14 percent or less) among all coal ranks.12
• Combustion: It is difficult to ignite but burns slowly with a pale blue flame, emitting relatively little smoke.1
• Formation: While other coals form through burial and temperature increases, anthracite requires higher temperatures (170 to 250 °C) often associated with igneous activity or significant tectonic folding.12