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
Allotropes of carbon Instead they were called zeolite-templated carbons (ZTCs). The name derives from their origin inside the pores of zeolites, crystalline silicon dioxide minerals. Another team recognized them as schwarzites and refined the original synthesis technique. A vapor of carbon-containing molecules is injected into the zeolite, where the carbon gathers on the pores' inner walls. It forms a 2D sheet that pulls inwards, creating the negative curve. Dissolving the zeolite leaves the carbon. Glassy carbon or vitreous carbon is a class of non-graphitizing carbon widely used as an electrode material in electrochemistry, as well as for high-temperature crucibles and as a component