slate

                                       
                                                               slate
What Type of Rock Is It? Metamorphic
What Minerals Make Up the Rock? micas, feldspars, quartz (but they can not be recognized because the grains are so small you would need a microscope to see them); Sometimes contain: pyrite
What Does It Look Like? Slate can be black, grey, brownish red, bluish grey, or greenish grey. It is very fine grained and has thin, quite smooth, flat layers. Unlike shale, slate easily splits into thin flat pieces. It often will scratch glass, with a little difficulty.
How Was It Formed? Slate is usually formed from clay sediments or shale that has been heated and put under pressure by plate collisions. The pressures and temperatures that form slate are lower than those that form schist.