BROWN COAL

as defined in the United States and Canada, type of lignitic subbituminous coal occurring in unconsolidated deposits. In Great Britain the term is used synonymously with lignites in general, and, in various continental European countries and Australia, it refers to lignites and subbituminous coals. The brown coal mined in North America varies in colour from yellow to dark brown and has a dull or earthy lustre. It often is banded, with layers of concentrated plant matter alternating with those of resinous materials. Thin layers of black lignite may also be present. Many brown coals of lighter colouring have a fibrous structure in which tree roots and other recognizable plant matter are still apparent, indicating little coalification beyond peat.