Coal the heat and pressure of deep burial causes the loss of water, methane and carbon dioxide and an increase in the proportion of carbon. Thus first lignite (also called "brown coal"), then sub-bituminous coal, bituminous coal, and lastly anthracite (also called "hard coal" or "black coal") may be formed. The wide, shallow seas of the Carboniferous Period provided ideal conditions for coal formation, although coal is known from most geological periods. The exception is the coal gap in the Permian–Triassic extinction event, where coal is rare. Coal is known from Precambrian strata, which predate land plants—this coal is presumed to
Coal in Australia tailings and chitter). The Federal Government has, as part of its pledge to mitigate global warming, committed A$100 million to commission a climate change-fighting "clean coal" and carbon sequestration research institute to make Australia a leader in this emerging technology. Carbon sequestration technology is not expected to be commercially viable for at least 5 to 10 years, but the Federal Labor government argues that it is a vital technology given Australia's reliance on coal-fired electricity. The merits of "clean coal" have been highly disputed by some technical experts and environment awareness groups. Coal in Australia Coal is mined in every