Anthracite Coal VB Aqua Water Treatment Industry. Anthracite coal filter helps to protect the Activated carbon filter bed, ... Hardness: 4 Mohs Hard grove: 38dHo Abrasion Value: Standard grain sizes. anthracite The Energy Library. anthracite. a hard, slowburning coal of the highest rank, ... and a hardness of 2 to on the Mohs scale.