1. Chapter 3 Section 7 How are metamorphic rocks classified?
Objective:
Explain the difference between foliated and nonfoliated metamorphic rocks.

2. Key Terms
foliated: texture of a metamorphic rock that has mineral crystals arranged in bands.
nonfoliated: texture of a metamorphic rock that does not have mineral crystals arranged in bands.

3. Classifying Metamorphic Rocks
Petrologists classify metamorphic rocks based on the texture of the rock. Metamorphic rocks have two kinds of textures, foliated and nonfoliated. The texture of a metamorphic rock is determined by the arrangement of its mineral crystals.

4. Classifying Metamorphic Rocks
CLASSIFICATION OF METAMORPHIC ROCKS
Original Rock
Metamorphic Rock
Texture
Granite, shale
Gneiss
Foliated
Granite, shale, basalt
Schist
Shale
Slate
Sandstone
Quartzite
Nonfoliated
Limestone
Marble

5. CLASSIFY:
How are metamorphic rocks grouped?

6. Banded Metamorphic Rocks
The mineral crystals in some metamorphic rocks are arranged in bands. The texture of a metamorphic rock with minerals arranged in bands is called foliated. Foliated rocks tend to break along their mineral crystal bands.

7. Banded Metamorphic Rocks
Foliated metamorphic rocks are formed when existing rocks are placed under great heat and pressure. Under this great heat and pressure, the minerals in the rocks melt and recrystallize into minerals that form bands.

8. Banded Metamorphic Rocks
Gneiss (NICE) is a foliated metamorphic rock. Gneiss is formed when granite is put under great heat and pressure.
Schist is another rock that has bands of recrystallized minerals. Schist is formed from shale, basalt, or granite. Slate is also formed from shale.

9. Banded Metamorphic Rocks

10. 2. COMPARE:
How are gneiss and schist similar?

11. Metamorphic Rocks Without Bands
The texture of a metamorphic rock that does not have its minerals arranged in bands is nonfoliated. Nonfoliated metamorphic rocks do not break in layers.
Marble and quartzite are nonfoliated metamorphic rocks. Marble is formed from limestone. Marble contains large mineral crystals of calcite.

12. Metamorphic Rocks Without Bands
Quartzite is formed from sandstone put under great heat and pressure. Quartzite has large crystals or quartz.

13. 3. IDENTIFY:
Which metamorphic rock has large crystals of quartz formed from sand?

14. Classwork CHECKING CONCEPTS What are two textures of metamorphic rock?
What causes banding in metamorphic rock?
How do foliated rocks break?
A metamorphic rock without banding has what kind of texture?

15. Classwork THINKING CRITICALLY
Use the “Classification of Metamorphic Rocks” table.
5. INTERPRET: Which metamorphic rocks are formed when granite is subjected to high heat and pressure?
6. INTERPRET: Which metamorphic rock is formed from limestone?
7. INTERPRET: Which metamorphic rocks can be formed from shale?
8. INTERPRET: From which sedimentary rock is quartzite formed?
9. CLASSIFY: Is slate a foliated or a nonfoliated metamorphic rock? Why?