| Slate is heavy, often dark colored and smooth
        when it breaks in sheets. It does not contain visible minerals, but with
        a microscope, you would see that all its minerals are lined up. The
        properties of slate make it ideal to use on the top of pool tables,
        shingles on roofs, walking stones, and the original blackboards, which
        teachers write on. Phyllite resembles slate but has a somewhat
        coarser texture. The flat surfaces have a lustrous sheen due to mica and
        chlorite. However, it is not as hard or flat as slate, and not used in
        construction like slate.  
         Slate outcrops in Grand Canyon
 |  Phyllite
  Slate roof
  
         |