Anthracite

Anthracite literally "a type of coal", is a hard, compact variety of mineral coal that has a high luster. It has the highest carbon count and contains the fewest impurities of all coals, despite its lower calorific content.
Anthracite is the most metamorphosed type of coal (but still represents low-grade metamorphism), in which the carbon content is between 92% and 98%.
Anthracite media is hydraulically classified to reduce foreign mineral matter and to lower ash content. The water filtration media is then screened and washed to ensure suitability for water filtration purpose . Anthracite characteristically produces reliable improvements in turbidity removal, mostly due to better solids holding capacity. Additionally, low uniformity coefficient media improves flow rates