Anthracite is a type of hard, high-carbon coal that is used in water treatment processes, primarily as a filtration media. It is known for its high density and hardness, making it an effective material for removing suspended particles, turbidity, and other impurities from water. Anthracite's angular shape and porous structure allow for efficient filtration, as it provides a large surface area for trapping contaminants. It's commonly used in both industrial and municipal water treatment systems, often in combination with other media like sand and gravel, to enhance water quality and clarity.