Unit Study Guide: Rocks, Minerals, and the Rock Cycle

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Name______________________________________________ Date__________________ Per____________

Unit 8.3.1 Study Guide: Rocks, Minerals, and the Rock Cycle

“I Can Statements” are the learning targets for each unit. By the time you take the test for this unit, you should be able to confidently say:

I can state the difference between rocks and minerals.

I can list and describe the properties that help identify the minerals found in rocks.

I can use defining characteristics to group rocks as sedimentary, metamorphic, or igneous.

I can diagram and explain the rock cycle.

One great way to study is to explain concepts to others. Teach the following concepts to a parent, grandparent, aunt, uncle, or even an older sibling.

– Rock Cycle (different rock types, processes that change from one rock type to another, etc.) – Sedimentary Rocks (examples, how they are formed, defining characteristics)

– Metamorphic Rocks (examples, how they are formed, defining characteristics) – Igneous Rocks (examples, how they are formed, defining characteristics) – Relationship between rocks and minerals

– Mineral properties (list and explain)

Signature _______________________________

Rock is a naturally formed, solid material that makes up the crust of the earth. Most rocks contain one or more minerals.

Some rocks may even contain organic compounds. Rocks are classified according to their origin. The rock cycle includes the processes by which rocks are made.

Summarize the paragraph(s) above:

I Can Statements

Teach the Concepts

Read/Summarize

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Igneous Rocks have their origin in molten magma and lava material. When they cool, they form different types of igneous rocks. Intrusive igneous rocks are formed when the magma cools beneath the surface of the earth. Magma, upon reaching the surface of the earth is called lava. Extrusive igneous rocks are formed from the cooling of lava on the surface of the earth. The three major types of igneous rocks include:

• basaltic rocks which are dense, heavy and dark-colored

• granitic rocks which are light-colored and less dense than basaltic rocks

• andesitic rocks which are intermediate between basalt and granite rocks

Sedimentary rocks are formed when fragments of rocks, minerals and/or organic material are compacted and cemented together.

• Clastic sedimentary rocks are formed when rocks and sediment are cemented together.

• Chemical sedimentary rocks precipitate out of solution or are left behind after evaporation has occurred.

Increases in heat and pressure can change both igneous and sedimentary rock into the third major form of rocks, namely, metamorphic rocks. When a rock undergoes metamorphosis, nearly every characteristic is changed, including texture and mineral composition. Under intense heat and pressure the minerals in a metamorphic rock will recrystallize in response to the stress. New crystals will grow in a specific orientation and old crystals will rotate to for an alignment or foliation seen in many metamorphic rocks as banding or layering of similar crystals. Schist and gneiss are examples of a foliated metamorphic rock showing visible bands or layers. Marble is an example of a non-foliated metamorphic rock.

Rocks are constantly changing from one type to another in a never-ending process known as the rock cycle. For instance, sediments of both metamorphic and igneous rocks, resulting from erosion and weathering, can become sedimentary rock.

Sedimentary rock can experience increases in pressure and heat and, thus, become metamorphic rock. Metamorphic rock can melt becoming magma, which in turn, can cool to become igneous rocks. Many of the characteristics of a rock (color, harder, reaction to acid, etc.) are directly related to the mineral that the rock is made from.

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Minerals: A mineral is a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition.

Inorganic: This means that the mineral cannot form from materials that were once part of a living thing. Crystal: the repeating pattern of a mineral’s particles forming a solid. Almost all minerals are compounds, meaning they are made of a combination of multiple elements. Some elements occur in nature in a pure form, and not as part of a compound with other elements.

Elements such as copper, silver, and gold are some of these, and are also minerals.

Each mineral has characteristic properties that can be used to identify it. Mineral Properties: color, streak, cleavage and fracture, luster, hardness, density, crystal structure.

• Color can be used to identify only those few minerals that always have their own characteristic color. This is one of the least effective ways to positively identify a mineral, because many mineral of the same type may come in different colors.

• Streak: The streak of a mineral is the color of its powder left behind when rubbing it against a hard surface like a tile.

• Luster is the term used to describe how light is reflected from a mineral’s surface. Luster types: Metallic, nonmetallic, vitreous (glasslike), adamantine (brilliant), waxy, resinous, and others.

• Hardness: The Mohs hardness scale ranks ten minerals from softest to hardest. A mineral can scratch any mineral softer than itself, but can be scratched by any mineral that is harder.

• Crystal structure: The crystals of each mineral grow atom by atom to form that mineral’s particular crystal structure.

Geologists classify these structures into six groups based on the number and angle of the crystal faces.

• Cleavage and Fracture: The way a mineral breaks apart can help to identify it. A mineral that splits easily along flat surfaces has the property called cleavage. Most minerals do not split apart evenly. Instead, they have a characteristic type of fracture, which describes how a mineral looks when it breaks apart in an irregular way.

• Additional properties of some minerals include: taste, smell, magnetism, fluorescence, and reaction to acid.

Check Yourself!

MINERALS

1. What are the five characteristics of a mineral?

2. What does naturally occurring mean?

3. What does it mean to have a definite chemical composition?

4. Explain Moh’s hardness scale. What are the hardest and softest minerals on the scale?

5. What is streak and how is it tested?

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6. Why is using only color a poor way to identify a mineral?

7. What other properties are useful for identifying a mineral? List four.

ROCK CYCLE AND ROCK TYPES 8. Draw and label the rock cycle.

9. Define each of the rock-forming processes, then tell which rock type(s) include this process in formation.

Process Define Part of formation of which rock type(s)?

(Sedimentary, Igneous, or Metamorphic) Cementation

Compaction Cooling

Complete Melting Crystallization Deposition Erosion Partial Melting Pressure Recrystallization Sedimentation Solidifying Weathering

10. Name the three basic types of rocks and describe how they form.

Rock Type How is it formed?

11. Explain the difference between intrusive and extrusive igneous rocks.

Intrusive Igneous Rock Extrusive Igneous Rock How is it formed?

Physical characteristics

12. Explain how you can tell the difference between and intrusive and extrusive igneous rock.

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13. Explain how it is possible for an igneous rock to be transformed into a metamorphic rock without going through a sedimentary phase.

14. Explain why it is not possible for sedimentary rocks to form underground.

15. Explain why metamorphic rocks always form underground.

16. For each rock type change, determine what process is taking place. In the arrow write the codes for the correct processes.

The first arrow is filled out for you as an example.

17. In the boxes below, explain how you could distinguish between each rock type.

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DIAGRAM A

18. For each letter on the rock cycle chart write the name of the process that takes place there. Choose from the list of processes below.

Processes

-MC (melting & cooling) -WESCC (weathering, erosion,

sedimentation, compaction & cementation) -HP (heat & pressure)

A__________ D__________ G__________

B__________ E__________ H__________

C__________ F__________ I __________

DIAGRAM B

19. Fill in the empty boxes and ovals in the Rock Cycle diagram to the right.

20. Both Diagram A and Diagram are accurate. Explain how they can both be accurate but look so different.

21. What can you conclude about diagrams that represent the rock cycle?

22. To the right are 11 rocks.

Your job is to sort each rock into its respective rock type bucket based on its defining characteristic.

Draw arrows from each rock to the appropriate bucket.

Figure

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References

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