Coal that has a gross calorific value less than 24 MJ/kg (determined in conformance
with ISO 1928), and vitrinite mean random reflectance less than 0.6% (determined in
conformance with ISO 7404-5). Gross calorific value is recalculated to a moist, ash
free basis using bed moisture (determined according to ISO 1015 or ISO 5068). Includes
all low-rank coals, including sub-bitiminous coal. A consolidated, dull, soft brown
to black coal having many readily discernible plant fragments set in a finer grained
organic matrix. Tends to crack and fall apart on drying. Operationally sub-bituminous
and bitiminous coal are qualitatively distinguished based on brown streak for sub-bitiminous
coal and black streak for bituminous coal.
example
brown coal
metalignite
ortholignite
sub bituminous coal
source
Economic commission for Europe, committee on Sustainable Energy- United Nations (ECE-UN),
1998, International Classification of in-Seam Coals: Energy 19, 41 pp.
