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.
Additional hazardous byproducts produced by coal-burning plants include, arsenic, chromium, cobalt, lead, manganese, zinc, radionuclides and particulate matter. Each type of coal produces different levels of these pollutants, all of which negatively impact both the environment and our health.hile that technology has in some ways benefited our society, we now recognize the ecological hazards and health risks associated with using coal as an energy source. Coal by itself is not harmful; however, the byproducts of burning coal raise serious health and environmental issues.