Coal that has vitrinite mean random reflectance greater than 2.0% (determined in conformance
with ISO 7404-5). Less than 12-14 percent volatiles (dry, ash free), greater than
91 percent fixed carbon (dry, ash free basis). The highest rank coal; very hard, glossy,
black, with semimetallic luster, semi conchoidal fracture.
source
Economic commission for Europe, committee on Sustainable Energy- United Nations (ECE-UN),
1998, International Classification of in-Seam Coals: Energy 19, 41 pp; see also Neuendorf
et al. 2005; http://en.wikipedia.org/wiki/Coal#Types_of_coal; Eberhard Lindner; Chemie
für Ingenieure; Lindner Verlag Karlsruhe, S. 258
