Metamorphic Rocks

Rocks

1. Rocks can go through changes where they become a brand new rock. This process is called __metamorphism__________.

2. This word is Greek. Meta means ____changed_______ and morphos means __shape________.

Rocks

3. Metamorphic rocks occur when the __structure_____, ___texture____, or __composition____ of the rock have changed.

4. All of these types of rock (__igneous________, _____sedimentary_____ and _____metamorphic_____) can be changed by __heat____, ___pressure___, or a combination of both.

Origins of Metamorphic Rock

5. Texture or mineral composition of a rock can change if the __temperature____ or __pressure____ of the new environment is different from the one that the rock was originally formed in.

6. The temperature that most metamorphism will occur is between __50__ oC to __1000__ oC. However some rocks will go through metamorphosis above 1000oC.

7. The __depth__ and __pressure___ that metamorphic rocks form is what allows the rock to heat to this temperature and stay solid.

Origins of Metamorphic Rock

8. The depth that most rocks go through metamorphic changes is at depths greater than _2_ km (kilometers) which is about 1.25 miles.

9. Large movements within the crust of the earth adds more _pressure__ on the rock during metamorphism. This can cause __mineral____ __grains___ in rock to align (line up) in certain directions.

Composition of Metamorphic Rock

10. Metamorphism happens when __temperature____ and ___pressure____ inside Earth’s crust change.

11. Original ___minerals___ change into new ___minerals____. For example calcite, quartz, and hematite will crystallize to form the metamorphic mineral __garnet__.

Textures of Metamorphic Rock

12. Scientists classify igneous, sedimentary, and metamorphic rocks by their __texture__.

13. Metamorphic rocks have two textures - __foliated____ or ___nonfoliated____.

Foliated Metamorphic Rock

14. The texture of a metamorphic rock that has mineral grains arranged in __planes___ or __bands___ is called __foliated___.

15. This metamorphic rock usually contains __aligned___ (lined up) grains of __flat_ minerals.

Foliated Metamorphic Rock

16. A metamorphic rock can continue to change into another __metamorphic____ rock if it exposed to more __heat___ and ___pressure____. For example: sedimentary shale becomes __slate___ (metamorphic), which become __phyllite___ with more heat and pressure. Then with more heat and pressure it can become __schist__, only to have more heat and pressure make it become _gneiss_.

Nonfoliated Metamorphic Rock

17. The texture of a metamorphic rock that has mineral grains that are not arranged in __planes___ or ___bands__ is called ___nonfoliated___. The minerals are not __aligned__ (not lined up).

18. These rocks are commonly made of _1__ or only a few minerals.

19. During metamorphism, the crystals of the minerals may change in __size___ or __composition___ called __recrystallization____.

Nonfoliated Metamorphic Rock

20. Examples of this are: quartz sandstone (sedimentary rock) is exposed to __heat__ and ___pressure___, and the minerals recrystallize to form __quartzite__; also limestone is exposed to __heat___ and __pressure___, and the minerals recrystallize and become ___marble____.

Metamorphic Rock Structures

21. When metamorphic rocks change shape because of force placed on them, they can be __squeezed___ or _stretched____. This is called __deformation___. Some deformations are called __folds__ or __bends__.

Examples

Quartzite is a coarse-grained metamorphic rock derived from sandstone.

Marble is a metamorphic rock that comes from metamorphosed limestone or dolomite.

Examples

Slate is a fined grained metamorphic rock.

Phyllite is a fined grained metamorphic rock.

Examples

Schist is a course grained metamorphic rock.

Gneiss is a medium to course grained metamorphic rock.