Coal

Coal (from the Old English term col, which has meant "mineral of fossilized carbon" since the 13th century CE) is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.

Throughout Terran history, coal has been used as an energy resource, primarily burned for the production of electricity and/or heat, and is also used for industrial purposes, such as refining metals. A fossil fuel, coal forms when dead plant matter is converted into peat, which in turn is converted into lignite, then sub-bituminous coal, after that bituminous coal, and lastly anthracite. This involves biological and geological processes that take place over a long period.

Coal was the largest source of energy for the generation of electricity on Terra, as well as one of the largest worldwide anthropogenic sources of carbon dioxide releases. In 2011 CE, gross emissions from coal usage were 14,416 million tonnes.

Coal is extracted from the ground by coal mining, either underground by shaft mining, or at ground level by open pit mining extraction. The top coal producer was China. In 2011 China produced 3,520 million tonnes of coal – 49.5% of 7,695 million tonnes world coal production, other large producers were United States (993), India (589), European Union (576) and Australia (416).

Other than by primitive cultures, coal is no longer used in the Union other than as a chemical feedstock

