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 Mylonite Uses. We have provided you with all information about Mylonite rock here. Mylonite is a metamorphic rock formed by ductile deformation during intense shearing encountered during folding and faulting, a process termed cataclastic or dynamic metamorphism. Mylonite is available in black to grey colors. The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Mylonite is white. Get to know more about Mylonite rock and characteristics of Mylonite rock in the next sections.