Rocks are naturally occurring solids which are composed of minerals & have been used by humans since ages. From Stone Age, rocks are used for various purposes. Also, the metals and minerals found in rock play an important role in our life. Get to know all the Lignite Uses. We have provided you with all information about Lignite rock here. Lignite is a soft brownish coal which shows traces of plants and is intermediate between bituminous coal and peat. Lignite is available in black, brown, dark brown, grey, light to dark grey colors. The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Lignite is black. Get to know more about Lignite rock and characteristics of Lignite rock in the next sections.