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 Chert Uses. We have provided you with all information about Chert rock here. Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture. Chert is available in black, brown, green, grey, red, white colors. The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Chert is white. Get to know more about Chert rock and characteristics of Chert rock in the next sections.