Editing Anthracite (section)

== Properties ==
[[File:Ibbenbueren Anthracite.JPG|thumb|Anthracite coal from [[Ibbenbüren, Germany]]]]
[[File:Anthracite coal (Photo by John Mortimore).jpg|thumb|Anthracite from [[Bay City, Michigan]]]]
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Anthracite is similar in appearance to the [[mineraloid]] [[jet (lignite)|jet]] and is sometimes used as a jet imitation.

Anthracite differs from ordinary [[bituminous coal]] by its greater hardness (2.75–3 on the [[Mohs scale of mineral hardness|Mohs scale]]),<ref name="USGSHardness">{{cite book | title=Mineral Resources of the Appalachian Region; USGS Professional Paper 580 | publisher=[[USGS]] | author=US Geological Survey and US Department of Mines | year=1968 | page=126}}</ref> its higher [[relative density]] of 1.3–1.4, and luster, which is often semi-metallic with a mildly green reflection. It contains a high percentage of fixed carbon and a low percentage of [[Volatility (chemistry)|volatile]] matter. It is also free from included soft or fibrous notches and does not soil the fingers when rubbed.{{sfn|Bauerman|1911|p=105}} 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 26 to 33 MJ/kg (22 to 28 million [[British thermal unit|Btu]]/[[short ton]]) on a moist, mineral-matter-free basis. The heat content of anthracite coal consumed in the United States averages 29 MJ/kg (25 million Btu/ton), on the as-received basis, containing both inherent moisture and mineral matter.

Since the 1980s, anthracite refuse or mine waste has been used for [[fossil fuel power plant|coal power generation]] in a form of [[recycling]]. The practice known as [[mine reclamation|reclamation]] is being applied to culm piles antedating laws requiring mine owners to restore lands to their approximate original condition.

Chemically, anthracite may be considered as a transition stage between ordinary bituminous coal and [[graphite]], produced by the more or less complete elimination of the volatile constituents of the former, and it is found most abundantly in areas that have been subjected to considerable stresses and pressures, such as the flanks of great mountain ranges.{{sfn|Bauerman|1911|p=105}} Anthracite is associated with strongly deformed [[sedimentary rock]]s that were subjected to higher pressures and temperatures (but short of metamorphic conditions) just as bituminous coal is generally associated with less deformed or flat-lying sedimentary rocks. The compressed layers of anthracite that are deep mined in the folded [[Ridge-and-Valley Appalachians|Ridge and Valley Province]] of the [[Appalachian Mountains]] of the [[Coal Region]] of East-central [[Pennsylvania]] are extensions of the same layers of bituminous coal that are mined on the generally flat lying and undeformed sedimentary rocks further west on the [[Allegheny Plateau]] of [[Kentucky]] and [[West Virginia]], Eastern [[Ohio]], and [[Western Pennsylvania]].

In the same way the anthracite region of [[South Wales]] is confined to the contorted portion west of [[Swansea]] and [[Llanelli]], the central and eastern portions producing [[steam coal]], [[coking coal]] and domestic house coals.{{sfn|Bauerman|1911|pp=105-106}}

Anthracite shows some alteration by the development of secondary divisional planes and fissures so that the original stratification lines are not always easily seen. The thermal conductivity is also higher; a lump of anthracite feels perceptibly colder when held in the warm hand than a similar lump of bituminous coal at the same temperature.{{sfn|Bauerman|1911|p=105}}

Anthracite has a history of use in [[blast furnace]]s for iron smelting; however, it lacked the pore space of metallurgical [[coke (fuel)|coke]], which eventually replaced anthracite.<ref>{{Harvnb|Rosenberg|1982|pp=89}}</ref>