| Metamorphic rocks result from the subjection of a parent rock (igneous, sedimentary, or metamorphic) to heat and/or pressure and/or chemically active fluids. Metamorphic rocks are classified according to the parent rock (protolith) and the degree of deformation to which the rocks have been subjected. Metamorphism occurs locally (contact) or on a large scale (regional). |
| Sedimentary parent rock |
Metamorphic product (low to high grade) |
| conglomerates | meta-conglomerates, schists, gneisses |
| breccias | meta-breccias, schists, gneisses |
| sandstone | quartzite, mica schist |
| shale/siltstone/claystone | phyllite, slate, schists, gneisses |
"fubarite"
| limestone/dolostone | marble (color shows "argillaceous" or "carboniferous") |
| peat/coal | anthracite through graphite with or without associated natural gas, petroleum and asphalt; Mississippi-type lead and zinc deposits |
