As with igneous and sedimentary rocks, metamorphic rocks are classified on the basis of texture (grain size, shape, orientation) and mineral composition. However, the classification of metamorphic rocks is more difficult to get into than with igneous and sedimentary rocks, for a couple of reasons.
Metamorphic rocks are classified as either foliated or nonfoliated . Foilated rocks have layers of mineral grains. Nonfoliated rocks have little or no layering. ( just took the test)
