Anthracite coal
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Coal_anthracite.jpg
Anthracite is a hard, compact variety of mineral coal that has a high luster. It differs from bituminous coal in that it contains little or no bitumen, therefore it burns with an almost invisible flame. The purer specimens consist almost wholly of carbon.
Anthracite coal is a product of metamorphism and is associated with metamorphic rocks, as bituminous coal is associated with sedimentary rocks. In the eastern United States, layers of bituminous coal that are strip mined on the (sedimentary) Allegheny Plateau of Kentucky and West Virginia are the same layers that are deep mined in the folded (metamorphic) Appalachian Mountains of Pennsylvania.
It was first experimentally burned as a fuel on February 11, 1808 by Judge Jeese Fell in Wilkes-Barre, Pennsylvania on a open grate in a fireplace.
Anthracite delivers high energy per its weight and burns cleanly with little soot, making it a sought after variety of coal and hence of higher value. It is also used as a filter medium.
In the early 20th century United States, the Lackawanna Railroad started using only the more expensive anthracite coal, dubbed themselves "The Road of Anthracite," and advertised widely that thanks to this travelers on their line could make railway journeys without getting their clothing stained with soot. The advertisements featured a white-clad woman named Phoebe Snow and poems containing lines like "My gown stays white / From morn till night / Upon the road of Anthracite".
Most anthracite coal in the United States is found in eastern Pennsylvania where there are 7 billion short tons (6.4 petagrams) of minable reserves. Deposits at Crested Butte, Colorado were mined historically. Anthracite deposits of an estimated 3 billion short tons (2.7 Pg) in Alaska have never been mined.
Anthracite is similar in appearance to the mineraloid jet, and is sometimes used to imitate it.
It is hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter. 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/ton (26 to 33 MJ/kg) on a moist, mineral-matter-free basis. The heat content of anthracite coal consumed in the United States averages 25 million Btu/ton (29 MJ/kg), on the as-received basis (i.e., containing both inherent moisture and mineral matter). Note: Since the 1980s, anthracite refuse or mine waste has been used for steam electric power generation. This fuel typically has a heat content of 15 million Btu/ton (17 MJ/kg) or less.