BGS Rock Classification Scheme
Lignite - A type of coal. It is a member of the pure humic coal series. The members of the pure humic coal series can be ranked in order as peat (the unlithified form), lignite, bituminous-coal, and anthracite (the lithified forms) based on increasing carbon content and decreasing volatile content. Lignite is a consolidated, dull, soft brown to black coal with many readily discernible plant fragments set in a finer-grained organic matrix. It tends to crack and fall apart on drying. Lignite may be further classified into brown-lignite and black-lignite. British Geological Survey Research Report RR/99/03, section 6.1, table 16 and fig. 10.
| Code | LIGN |
|---|---|
| Description | Lignite - A type of coal. It is a member of the pure humic coal series. The members of the pure humic coal series can be ranked in order as peat (the unlithified form), lignite, bituminous-coal, and anthracite (the lithified forms) based on increasing carbon content and decreasing volatile content. Lignite is a consolidated, dull, soft brown to black coal with many readily discernible plant fragments set in a finer-grained organic matrix. It tends to crack and fall apart on drying. Lignite may be further classified into brown-lignite and black-lignite. British Geological Survey Research Report RR/99/03, section 6.1, table 16 and fig. 10. |
| Qualifiers | No qualifiers currently exist. |
| Definition | Lithified soft brown/black coal, mixture of a wide range of plant debris many individually discernable. Fine-grained 0.032-2mm organic matrix. 60 to 75% carbon, dry, ash-free. Volatiles 46 to 63%. Partly carbonised, cracks & breaks on drying. |
| Linked data | http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/LIGN |
CAVEAT
"Thumbnail" definitions attached to some of the table entries are an interim attempt to provide simple short descriptions of the "unqualified" rock types presented within the BGS Rock Classification Scheme. Every effort has been made to ensure accuracy and consistency but minor contradictions or omissions might be present. The BGS welcomes any feedback pointing out such minor imperfections and/or providing constructive comment and suggestions for improvement of the definitions. In the first instance such feedback should be directed to Dr Tim McCormick.