Anthracite Coal

Hardness: 2.5-2.75 (Mohs scale), Color: Black to dark grey, Luster: Bright, glassy to submetallic, Crystal structure: Amorphous (no defined crystal structure), Cleavage: None (conchoidal fracture), Specific gravity: 1.3-1.8

Anthracite is formed from peat through increasing amounts of pressure and temperature (metamorphism), which removes water and other impurities. It is the highest rank of coal, representing the final stage of coalification. Its formation typically occurred during the Carboniferous period (about 360 to 300 million years ago) from ancient plant matter in ancient swamps and peat bogs.

Primarily used as a clean-burning fuel for residential and commercial heating due to its high carbon content and low volatile matter. Less common than other coal types for industrial power generation because of its higher cost and difficulty in ignition compared to bituminous coal. Historically, it was used in blast furnaces for iron production.

Also known as 'hard coal,' anthracite has the highest carbon content (typically 86-98%) and the fewest impurities of all coal types. It burns with a short, blue, smokeless flame and produces intense heat. The largest anthracite deposits in the world are found in eastern Pennsylvania, USA.

Identify it by its distinct shiny, almost metallic luster (often described as submetallic or vitreous), its black color, and its conchoidal fracture (breaks with a curved, shell-like surface). It is harder and denser than other coal types. It typically doesn't stain hands when handled, unlike lower-grade coals. Common locations include folded mountain belts such as the Appalachian Mountains in the USA, and regions in China, Russia, Ukraine, South Africa, and Vietnam. For collectors, well-formed specimens showcasing its unique luster and fracture patterns are desirable.