The Many Names of Coal
| By Rank | |
| Coal Rank |
BTU |
| Subbituminous coal | 8,000 to 10,000 |
| Bituminous coal | 10,000 to 14,000 |
| Anthracite coal | 12,000 to 14,000 |
| By Origin | |
| Origin | Explanation |
| Boghead coal | Coal derived primarily from algae. |
| Cannel Coal | Coals made up of microspores settling underwater as in a lake. |
| Humic Coal | Coals derived primarily from woody tissue |
| Sapropelic Coal | Coal derived primarily from spores and algae |
| Hard Coal | Bituminous and anthracite coals |
| Brown Coal | Sometimes used for lignite and in some countries, subbituminous. |
| Lignite | Not a true coal, formed from peat that was never deeply buried |
| By Use | |
| Grade Name | Explanation |
| Steam coal | Coal used in electrical power plants to produce the steam that runs generators. |
| Metallurgical coal | Coal suitable for making coke for use in steel making blast furnaces. |
| Coke | Produced by partially burning coal in a reduced oxygen atmosphere. This removes most of the gasses leaving a solid that burns with a higher temperature than coal. There are two grades of coke |
| Chemical Coke | Chemical grade coke is a lower grade and is used for reducing phosphate rock in electric furnaces and in the production of calcium carbide. |
| Metallurgical Coke | Metallurgical grade coke produces a much higher temperature and is used as the heat source in blast furnaces for making iron etc. |
| By Ash Content | |
| Ash Content | Percent Ash |
| Low ash coal | 3% to 8% |
| Medium ash coal | 8% to15% |
| High ash coal | > 15 % |
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