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 Marl Uses. We have provided you with all information about Marl rock here. Marl is an unconsolidated sedimentary rock consisting of clay and lime. Marl is available in beige, brown, green, grey, white colors. The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Marl is white. Get to know more about Marl rock and characteristics of Marl rock in the next sections.