Lignite 5 : Brownish-black coal, intermediate between peat and bituminous coal; especially one in which the texture of the original wood is distinct (synonym Brown Coal). (Bul 10C)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}