The Association of United States property in materials testing and characterization of coal is the 4 series.Characterization of coal as a 4 series.By carbon, from the most to least is: anthracite bikini 2 Minas. SAP Business 2 Minas and lignite
Testing and Materials Society of the United States has identified four priority coal is classified into four coal-order types, which are arranged from highest to lowest carbon anthracite, bituminous coal and lignite, sub-bituminous coal.