Anthracite Coal

Hardness: 2.5-2.75 on Mohs scale. Color: Black to dark grey. Luster: Vitreous to sub-metallic (bright, shiny). Crystal structure: Amorphous, no true crystal structure. Specific Gravity: 1.3-1.8. It is brittle and has a conchoidal fracture.

Anthracite coal forms from peat through a process called coalification, which involves intense pressure and heat from burial within the Earth's crust over millions of years. It is considered the highest rank of coal, representing the final stage of coal formation. Its geological age typically ranges from Carboniferous to Permian periods, approximately 359 to 252 million years ago.

Primarily used as a clean-burning fuel for residential and industrial heating due to its high carbon content and low volatile matter. It is also used in some industrial processes as a filter medium and in the production of carbon electrodes.

Anthracite is known as 'hard coal' and produces more energy per pound than other types of coal (bituminous, sub-bituminous, and lignite) while burning with less smoke. It is relatively rare, accounting for only about 1% of the world's total coal reserves. The largest known deposits are found in Pennsylvania, USA.

In the field, anthracite can be identified by its jet-black color, bright, almost metallic luster, and its hardness (it should be difficult to scratch with a fingernail). It often has a conchoidal (shell-like) fracture. It does not easily smudge or leave significant black residue when handled, unlike lower grades of coal. Common locations include Eastern Pennsylvania (USA), parts of Wales (UK), Russia, Ukraine, and China.