schist mineral rock specimen from mining and quarrying industries. schist is a medium-grade metamorphic rock with medium to large

aged ancient biotite brown coarse crystal decorative extraction formation fossil gemmology gemological gemology geologic geological geology gray grunge industry layered material metamorphic mica mineral mineralogy mining natural nature object old ore ornamental pattern pebble piece quartz quartzbiotite raw rock rough rustic sample schist shale specimen stone surface texture textured wild