Regional Metamorphism Regional metamorphism is caused by large movements of the Earth's crust such as mountain building creating great pressure and heat on the rocks forming the crust. The rocks becomes folded over each other, twisted and doubled. Some minerals that are common to all types of rock are quartz, feldspar and muscovite. Some minerals found only, or mainly in metamorphic rocks are garnet, kyanite, staurolite, cordierite, epidote, and chlorite. Many minerals growing in this type of rock tend to have crystals growing in a particular direction.
New minerals grow at right angles to the direction of maximum pressure.
They will likely have cleavage in that direction as well. Rocks such as marbles and quartzite do not develop a visible fabric as a rule. They have iron minerals. This article may not be copied, distributed or reprinted in any form without the author's permission. To contact the author, please use the e-mail address provided.