What are the characteristics of high grade metamorphic rocks?

Slate is a product of low grade metamorphism (not terribly great burial temperatures and pressures are required). Schist and gneiss are produced by medium to high grade metamorphism. In some cases gneisses are produced by higher grade metamorphism than schists. read more

staurolite marks the next metamorphic grade, which is medium-high grade; sillimanite is a characteristic mineral of high grade metamorphic rocks; Index minerals are used by geologists to map metamorphic grade in regions of metamorphic rock. read more

High grade metamorphic rock will appear very solid. All the minerals will be melted and compressed together. Quartzite is a case where the quartz grains of sandstone are compressed to the point that they fuse together around their margins. read more

Metamorphic rocks can be formed from sedimentary, igneous and even other metamorphic rocks. The composition of the rocks as well as the temperature and amount of pressure placed on them all play a role in the type of metamorphic rock formed. For this reason, metamorphic rocks can take on all types of colors and textures. However, foliation and lineation are two characteristics commonly seen in metamorphic rocks and are used to help identify and classify the rocks. read more