1. Earth Science
Metamorphic rockS

2. Origins of Metamorphic Rock
Start with a parent rock
Can be sedimentary, igneous, or metamorphic
Metamorphic rocks
Rocks in which the structure, texture, or composition of the rock have changed (metamorphosis)
changed by heat, pressure, or a combination of both

3. Contact metamorphism
When magma moves through the crust, the magma heats the surrounding rock and changes it.
Some minerals in the surrounding rock are changed into other minerals by this increase in temperature.
The greatest change occurs where magma comes into direct contact with the surrounding rock.

4. Regional metamorphism
occurs when pressure builds up in rock that is buried deep below other rock formations
or when large pieces of the Earth’s crust collide with each other.
The increased pressure and temperature causes rock to become deformed and chemically changed.

5. Composition of Metamorphic Rock
As rocks undergo metamorphism
the original minerals in a rock change physically or chemically into new minerals that are more stable within the new pressure and temperature conditions.
calcite + + +
Heat and Pressure =
quartz
hematite
Garnet

6. Texture of Metamorphic Rock
Two types:
Foliated Metamorphic Rock
Mineral grains are arranged in ribbons or bands
Usually contains aligned grains of flat minerals, such as biotite mica or chlorite
GNEISS
GRANITE
Heat / Pressure

7. Example of a foliated metamorphic rock

8. Although the bands are very small – slate, phylite, and schist are foliated.
Shale
(PARENT ROCK)
Slate
Phylite
Schist

9. Nonfoliated Metamorphic Rock
QUARTZITE
SANDSTONE
Heat / Pressure
Nonfoliated Metamorphic Rock
Mineral grains are not arranged in ribbons or bands
commonly made of one or only a few minerals.

10. Exmaples of nonfoliated metamorphic rock
undergoes
metamorphism
limestone
Marble
undergoes
metamorphism
Anthracite Coal
Bituminous Coal

12. ROCK LAB Slate Foliated Parent Rock: Shale/mudstone
smooth, dull, dark, layers
Marble
Nonfoliated
Parent Rock: limestone
fused calcite crystals, light color

13. Gneiss Quartzite Nonfoliated Foliated Parent Rock: Granite
dark/light bands
Quartzite
Nonfoliated
Parent Rock: Sandstone
Fused quartz crystals

14. Schist
Foliated
Parent Rock: Phyllite
flakey mica layers

15. THINK!
Would it be better to build a statue made of gneiss or marble? WHY? (think of the parent rocks)