Objectives Describe the conditions under which metamorphic rocks form Identify the ways in which geologists classify metamorphic rocks
Vocabulary Word foliated
How Metamorphic Rocks Form Heat and pressure deep beneath Earth’s surface can change any rock into metamorphic rock. Metamorphic rock can form out of igneous, sedimentary, or other metamorphic rocks.
Heat Forming Metamorphic Rock Forces inside Earth can push the rock down toward the heat of the mantle. Pockets of magma rising through the crust provides this heat. granitegneiss shale slate
Pressure Forming Metamorphic Rock The deeper rock is buried in the crust, the greater the pressure on that rock
Classifying Metamorphic Rocks Geologists classify metamorphic rocks by the arrangement of the grains that make up the rock. –When the grains are arranged in parallel layers or bands, they are FOLIATED. –Examples include slate and gneiss.
Slate Common foliated rock. Came from sedimentary rock Shale. Becomes slate with the addition of heat and pressure. –Mica and hornblende form in the slate.
Non-foliated Metamorphic Rocks Mineral grains are arranged randomly. Marble and quartzite are examples. Sandstone Quartzite
Uses of Metamorphic Rocks Marble and slate are the two most useful. –Building material. –Materials used for statues.