Metamorphic Rocks
Metamorphic rocks are those which have been changed from one form to another by the high pressure and temperature environment of the Earth. "Metamorphism" means the process of changing form. The changes can be applied to either sedimentary or igneous rock. Lutgens and Tarbuck provide a useful table of some of the varieties of metamorphic rock.
Metamorphic
rock | Texture | Parent
rock | Description |
| Slate | Foliated | Shale | Very fine grained |
| Phyllite | Foliated | Shale | Fine-to-medium grained |
| Schist | Foliated | Shale, granitic and volcanic rocks | Coarse-grained micaceous minerals |
| Gneiss | Foliated | Shale, granitic and volcanic rocks | Coarse-grained, non-micaceous |
| Marble | Nonfoliated | Limestone, dolostone | Composed of interlocking calcite grains |
| Quartzite | Nonfoliated | Quartz sandstone | Composed of interlocking quartz grains |
| Hornfels | Nonfoliated | Any fine-grained material | Fine-grained |
| Migmatite | Weakly foliated | Mixture of granitic and mafic rocks | Composed of contorted layers |
| Mylonite | Weakly foliated | Any material | Hard, fine-grained rock |
| Metaconglomerate | Weakly foliated | Quartz-rich conglomerate | Strongly stretched pebbles |
| Amphibolite | Weakly foliated | Mafic volcanic rocks | Coarse-grained |
|
Index
Reference
Lutgens and Tarbuck
Ch 7 |