1. C HAPTER 5: R OCKS Section 1: Classifying Rocks

2. W HAT ARE ROCKS MADE OF ? Rocks are mixtures of minerals and other materials. Some contain only a single mineral; others contain several minerals (ex. granite = quartz + feldspar + hornblende + mica) Rock-forming minerals : approx. 20 common minerals that make up most of the rocks of Earth’s crust

3. L ECTURE C HECK 1 Question: What are rocks made of?

4. L ECTURE C HECK 1 Question: What are rocks made of? Answer: Mixtures of minerals and other materials

5. M INERAL C OMPOSITION AND C OLOR Color provides clues to the rock’s mineral composition Granite : light-colored rock with high silica content Basalt : dark-colored rock with low silica content Shape and color of crystals Tests used to identify minerals (e.g. acid test)

6. L ECTURE C HECK 2 Question: How is silica content related to color?

7. L ECTURE C HECK 2 Question: How is silica content related to color? Answer: High-silica content is associated with lighter color and low-silica content is associated with darker color.

8. T EXTURE Texture : look and feel of the rock’s surface Grain : particles of minerals or other rocks, which give the rock its texture Size: coarse, fine Shape: rounded, jagged Pattern: banded, nonbanded

9. L ECTURE C HECK 3 Question: What are the three things that you can observe about grain?

10. L ECTURE C HECK 3 Question: What are the three things that you can observe about grain? Answer: size, shape, and pattern

11. C LASSIFYING R OCKS Geologists must use color, composition, texture, and other tests to classify and identify rocks.

12. H OW R OCKS F ORM Three groups of rocks based on origin Igneous : form from cooling of magma or lava Sedimentary : form when particles of other rocks or the remains of plants and animals are pressed and cemented together; layers buried below the surface Metamorphic : form when an existing rock is changed by heat, pressure, or chemical reactions; most deep underground

13. L ECTURE C HECK 4 Question: Limestone forms on the ocean floor in tropical environments. What type of rock do you think limestone is?

14. L ECTURE C HECK 4 Question: Limestone forms on the ocean floor in tropical environments. What type of rock do you think limestone is? Answer: sedimentary

15. P OST - LESSON Q UIZ 1. What type of rock is formed when an existing rock is changed by intense heat and pressure deep underground? a. sedimentary b. igneous c. metamorphic d. mineral

16. P OST - LESSON Q UIZ 2. What type of rock is formed from magma or lava cooling? a. sedimentary b. igneous c. metamorphic d. mineral

17. P OST - LESSON Q UIZ 3. What type of rock forms when particles of other rocks or the remains of plants and animals are pressed and cemented together? a. sedimentary b. igneous c. metamorphic d. mineral

18. P OST - LESSON Q UIZ 4. What term describes the look or feel of a rock’s surface? a. texture b. grain c. density d. mass

19. P OST - LESSON Q UIZ 5. Which is not a characteristic that can be used to identify rocks? a. color b. crystal shape c. reaction to acid d. size of rock