Lignite, often referred to as brown coal, is a soft brown combustible sedimentary rock formed from naturally compressed peat. It is considered the lowest rank of coal due to its relatively low heat content. It has a carbon content around 25-35%. It is mined all around the world and is used almost exclusively as a fuel for steam-electric power generation, but is also mined for its germanium content in China. As of 2014, about 12% of Germany's energy and, specifically, 27% of Germany's electricity comes from lignite power plants, while in Greece, lignite provides about 50% of its power needs.