1. Metamorphic Rocks

2. What is a metamorphic rock?
Rocks that have changed
once another rock
Pressure and heat changed the rocks
without melting
Rock has undergone metamorphism

3. Temperature Heat lower limit is 150ºC,
causes molecular expansion
stretches and weakens the bonds in minerals
crystals tend to grow larger by joining together.
minerals can lose water and change minerals
reactions may occur between minerals.
lower limit is 150ºC,
upper limit is the melting temperature

4. Pressure Compresses minerals Causes stress break some bonds
new minerals form
re-oriented minerals

5. Metamorphic Grade High Grade Metamorphism Low Grade Metamorphism
High heat
High pressure
Low Grade Metamorphism
Low heat
Low pressure

6. Types Regional Contact Hydrothermal Large area
Magma touches (comes in contact w/) rock
Hydrothermal
Hot water dissolves minerals
Deposits new minerals

7. Regional Metamorphism
widespread metamorphism
often associated with mountain building

8. Contact Metamorphism heat and sometimes fluid
intrusion of magma into the shallow crust,
Contact metamorphism can also be found in the soil or rock underlying a lava flow.

9. Hydrothermal Metamorphism
Quartz
Hydrothermal solutions
hot water with dissolved minerals
Metallic ore deposits
Can introduce new minerals
Slate

10. Textures Foliated Nonfoliated Preferred orientation Minerals flattened
Blocky crystal shape
No preferred orientation

11. Foliation High Grade Minerals align Because of pressure Granite (top)
Gneiss (bottom)
Same minerals
Foliation in Gneiss

12. Non-Foliated
Low Grade
Low heat/pressure
Crystals can grow

13. Identification Texture Grain size Mineral Composition Foliated
Non foliated
Grain size
Fine grained
Coarse Grained
Mineral Composition

14. Foliated Rocks Non-Foliated
Slate
Schist
Gneiss
Quartzite
Marble

15. Parent rock to Metamorphic

16. Uses of Metamorphic Rocks
Art Sculptures
Marble
Building material
Floor tiles
Counters
Old Chalkboards
Slate

17. Major Concepts Can be formed from any rock
igneous, sedimentary, or existing metamorphic rocks
Involves recrystallization in the solid state
Little change in chemical composition
Driving forces are
changes in temperature, pressure, and pore fluids.
Minerals and new textures are formed