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Igneous Rock Lab
Note: Remember you are responsible for graphs, charts and other items that form part of the overall summary of this topic. You will need a copy of the Earth Science References tables.
Background: Igneous rock is one of the three (3) main types of rocks. Igneous rock is formed by magma or lava becoming cooled and solidifying. The rock may form with or without crystallization below the surface or on the surface of the planet. Remember that magma is molten rock below the Earthís surface while lava is molten rock that has erupted onto the Earthís surface through a volcano or fissure (crack) in the Earthís surface. Lava cools much more quickly than magma because it is on the surface. Cooling rates influence the texture of igneous rocks: quick cooling will give fine grains while slower cooling will result in coarse grains. Remember that igneous rocks are classified based on their texture and composition.
Directions: Using the ESRTís answer the following questions:
1. What is the texture of rhyolite?
2. What is the crystal size of rhyolite?
3. Is rhyolite intrusive or extrusive?
4. Plutonic is also referred to as intrusive or extrusive?
5. Estimate the percentage of each mineral in rhyolite:
a. __________% Potassium Feldspar
b. __________% Quartz
c. __________% Biotite
d. __________% Amphibole (hornblende)
6. List the minerals in andesite.
7. What is the texture of scoria?
8. Name a fine-grained igneous rock with no quartz.
9. Name a coarse-grained igneous rock with no quartz.
10. Which mineral is present in much greater quantities in peridotite than in gabbro?
11. What is the texture of granite?
12. What is the crystal size of granite?
13. Is granite intrusive or extrusive?
14. Estimate the percentage of each mineral in gabbro:
a. __________% Plagioclase Feldspar
b. __________% Pyroxene
c. __________% Olivine
d. __________% Amphibole
e. __________% Biotite
15. Name a fine-grained textured igneous rock with no pyroxene.
16. Name a coarse-grained textured igneous rock with no pyroxene.
17. Contrast rhyolite and basalt in the following categories:
c. percentage of Iron (Fe) & Magnesium (Mg)
d. percentage of Quartz
18. Name a felsic intrusive rock.
19. Name a light-colored plutonic rock.
20. Felsic rocks generally have a __________ color.
21. Mafic rocks generally have a __________ color.
22. Intrusive igneous rocks have large or small mineral crystals because of slow or fast cooling?
23. Name four (4) felsic igneous rocks:
24. Name four (4) mafic igneous rocks:
25. Name a plutonic mafic igneous rock.
26. Which igneous rock cooled slowly underground and contains mostly quartz and potassium feldspar?
27. How does the percentage of aluminum in an igneous rock affect its density?
28. Which igneous rock is fine-grained and has a lot of pyroxene?
29. Name a coarse-grained igneous rock composed mostly of olivine.
30. Name an intrusive, dense, dark igneous rock.
31. What two (2) characteristics are used to classify igneous rocks?
32. Where an igneous rock formed can be inferred from the rocks __________.
33. What causes the differences of texture in igneous rocks?
34. Fill in the blanks on the following chart:
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