Lecture 7

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6.3 What is the role of pressure in metamorphism?

• Pressure increases with depth into Earth, which causes many minerals to metamorphose into denser minerals that are more stable at high pressure.
• Recrystallization at high pressure changes rock texture without changing chemical composition or mineral content.
• Foliation describes planes of minerals formed in response to stress. It is recognized by a preferred orientation of minerals, or reshaped or alternating bands of minerals.