Rock Name | Grade | Grain Size | Parent Rock | ||
Fine Grained |
Shale or Mudstone |
||||
Shale |
|||||
Medium to |
Shale, basaltic rocks |
||||
Shale, Granite, Andesite |
|||||
Basalt, Gabbro |
|||||
Fine Grained |
Any rock type |
||||
Peat, Lignite, or Bituminous Coal |
|||||
Basalt, Gabbro, or Peridotite |
|||||
Fine to Coarse Grained |
Limestone, Dolostone |
||||
Quartz Sandstone |
|||||