Earth and Space Science / Unit 2: Minerals and Rocks
2.6 Metamorphic Rocks
Notes
Metamorphic rocks form when existing rock is changed by heat, pressure or hot fluids, but without melting.
- Foliated rocks have layered or banded minerals from directed pressure: slate, schist, gneiss.
- Nonfoliated rocks have no layers: marble (from limestone), quartzite (from sandstone).
- Increasing metamorphism: shale becomes slate, then phyllite, schist and gneiss.
- If rock melts, it becomes magma and later igneous rock, not metamorphic.
Practice
Marble forms when which rock is metamorphosed?
Heat and pressure recrystallize limestone into marble.
What is the key difference between metamorphism and melting?
Metamorphic rocks change in the solid state.
Rock with distinct bands of light and dark minerals is most likely:
Gneiss is a coarse banded foliated rock.
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