 __notoc__ thumb|lignite   lignite, often referred to as brown coal, is a soft brown combustible sedimentary rock that is formed from naturally compressed peat. it is considered the lowest rank of coal due to its relatively low heat content. it is mined in china, bulgaria, greece, germany, poland, serbia, russia, turkey, the united states, canada, india, australia and many other parts of europe and it is used almost exclusively as a fuel for steam-electric power generation, but is also mined for contained germanium in china. 45% of germany's electricity comes from lignite power plants, while in greece lignite provides about 50% of its power needs. ==characteristics== lignite is brownish-black in color and has a carbon content of around 25-35%, a high inherent moisture content sometimes as high as 66%, and an ash content ranging from 6% to 19% compared with 6% to 12% for bituminous coal. the energy content of lignite ranges from  (9â17 million btu per short ton) on a moist, mineral-matter-free basis. the energy content of lignite consumed in united states averages  (13 million btu/ton), on the as-received basis (i.e., containing both inherent moisture and mineral matter). the energy content of lignite consumed in victoria, australia averages  (6.5 million btu/ton).  lignite has a high content of volatile matter which makes it easier to convert into gas and liquid petroleum products than higher ranking coals. unfortunately its high moisture content and susceptibility to spontaneous combustion can cause problems in transportation and storage. it is now known that efficient processes that remove latent moisture locked within the structure of brown coal will relegate the risk of spontaneous combustion to the same level as black coal, will transform the calorific value of brown coal to a black coal equivalent fuel while significantly reducing the emissions profile of 'densified' brown coal to a level similar to or better than most black coals.george, a.
Coal Organic_minerals