Anthracite Mohs scale), its higher relative density of 1.3–1.4, and luster, which is often semi-metallic with a mildly brown reflection. It contains a high percentage of fixed carbon and a low percentage of volatile matter. It is also free from included soft or fibrous notches and does not soil the fingers when rubbed. Anthracitization is the transformation of bituminous coal into anthracite. The moisture content of fresh-mined anthracite generally is less than 15 percent. The heat content of anthracite ranges from 22 to 28 million Btu per short ton (26 to 33 MJ/kg) on a moist, mineral-matter-free basis. The heat content
Coal liquefaction well as from generation of necessary process heat and electricity inputs to the liquefaction reactors, thus releasing greenhouse gases that can contribute to anthropogenic global warming. Especially if coal liquefaction is conducted without any carbon capture and storage technologies. There are technically feasible low-emission configurations of CTL plants. High water consumption in the water-gas shift reaction or steam methane reforming is another adverse environmental effect. Pyrolysis of coal produces polycyclic aromatic hydrocarbons, which are known carcinogens. On the other hand, synthetic fuels produced by indirect coal liquefaction processes tend to be 'cleaner' than naturally occurring crudes, as heteroatom (e.g. sulfur)