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