Section 3-7 How are metamorphic rocks classified? Earth Science Section 3-7 How are metamorphic rocks classified?

Classifying Metamorphic rocks Petrologists (those who study rocks, and how they are formed) classify metamorphic rocks based on the texture of the rock. Metamorphic rocks have 2 kinds of textures: foliated, and nonfoliated. Original rock Metamorphic rock Texture Granite, shale Gneiss Foliated Granite, shale, basalt Schist Shale Slate Sandstone Quartzite Nonfoliated Limestone Marble nonfoliated

Branded Metamorphic Rocks Foliated Texture: The mineral crystals in foliated metamorphic rocks are arranged in bands.—These rocks tend to break along the crystal bands. Foliated rocks are formed when existing ricks are placed under great heat and pressure until they melt and recrystallize into mineral that form bands EX: Gneiss, Schist

Metamorphic Rocks Without Bands Nonfoliated Rocks: Metamorphic Rocks that don’t have their minerals arranged in bands. Nonfoliated Rocks do not break into layers. EX: Marble and Quartzite