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 Limestone Uses. We have provided you with all information about Limestone rock here. Limestone is a sedimentary rock composed mostly of calcite and aragonite, which are different crystal forms of calcium carbonate. Limestone is available in beige, black, blue, brown, cream, gold, green, grey, light green, light grey, linen, pink, red, rust, silver, white, yellow colors. The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Limestone is white. Get to know more about Limestone rock and characteristics of Limestone rock in the next sections.