When the figure is not level people cannot know what is meant by width, depth, or height without being told (or without labels), although length is generally still assumed to mean the direction in which the figure is longest..
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.oal is primarily used as a solid fuel to produce electricity and heat through combustion. World coal consumption was about 7.25 billion tonnes in 2010 (7.99 billion short tons) and is expected to increase 48% to 9.05 billion tonnes (9.98 billion short tons) by 2030.
Coal, the Organic Rock. Coal differs from every other kind of rock in that it is made of organic carbon: the actual remains, not just mineralized fossils, of dead plants.Today the vast majority of dead plant matter is consumed by fire and decay, returning its carbon to the atmosphere as the gas carbon dioxideâit is oxidized.irst the swampy peat is squeezed and heated to form a brown, soft coal called lignite. In the process, the material releases hydrocarbons, which migrate away and eventually become petroleum. With more heat and pressure lignite releases more hydrocarbons and becomes the higher-grade bituminous coal.