| Since the mountains of Appalachia were rich in anthracite, a superior grade of coal, the industry grew rapidly. |
| Coal is usually classified into the sub-groups known as anthracite, bituminous, lignite, and peat. |
| Some anthracite is as fully xyloid as are some lignites and semi-bituminous coals. |
| For more than twenty years the anthracite miners have groaned under most intolerable and inhuman conditions. |
| Depending on the degree of carbon concentration and coalification, one differentiates between lignite, bituminous coal and anthracite. |
| In 1840 iron ore had only recently been discovered and anthracite coal mining had not yet begun. |
