IAES Rocks and Minerals: Activity 20 “Identifying Rock Types” Absent Work

Key Words: No new key words.

Getting Started: 1. Read the Introduction and Challenge to Activity 20, “Identifying Rock Types,” in your Student Book on page B-37.

2. Look at Table 1, “Rock Characteristics,” on page B-38 of your Student Book. Review how to identify rocks by rock type. Note the box on page B-39 that shows the relative size of crystals. Unlike the mineral samples examined so far, the size of most mineral crystals is small. The large crystals referred to in the table would be no larger than 0.5 centimeters, while small crystals are generally not even visible without magnification.

Procedure: Part A: Identifying Rock Types 1. Watch the video link below to observe each of the rock samples. Note: When making your observations, ignore the spot of paint used to help identify the rock.

http://www.youtube.com/watch?v=jg6TgPHLy8s

2. Compare each rock to the identifying characteristics in Table 1. Record your observations on Student Sheet 20.1, “Rock Data,” that is attached to this packet. Focus on those observations that help you identify each as either an igneous, metamorphic, or sedimentary rock.

3. Identify each rock as being igneous, sedimentary, or metamorphic on Student Sheet 20.1.

Part B: Identifying the Hikers’ Rock 4. Watch the video link below to observe the hiker’s rock. Compare the rock with the identifying characteristics show in Table 1 above. Hint: Your sample may contain garnets, which are large reddish-brown crystals. When examining crystal size, ignore the garnets and focus instead on the size of the crystals in the rest of the rock. 5. Record your observations on the hiker’s rock on Student Sheet 20.1.

6. Identify the hikers’ rock as being igneous, sedimentary, or metamorphic on Student Sheet 20.1.

Analysis Questions: 1. Do all rocks of the same type, such as all igneous rocks, look the same? Support your answer with evidence from your observations.

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2. What characteristic was most useful in identifying each type of rock listed below? Explain. a. igneous b. metamorphic c. sedimentary

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3. Help Ranger Ormond identify the hikers’ rock by examining the table below.

a. Based on your observations of the rock sample, which rock do you think the hikers found? b. Support your answer with evidence from your investigation. c. Could the hikers have seen diamonds? Explain.

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4. Imagine having to identify another rock. Which of the following facts would be the most helpful to you? Explain your reasoning.

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Follow-Up: 1. What do you think Ranger Ormund should do now?

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