Modified True/False
Indicate
whether the sentence or statement is true or false. If false, change the identified word or
phrase to make the sentence or statement true.
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1.
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Magma
is a slushy mix of molten rock, gases, and mineral crystals.
_________________________
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2.
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Porphyritic textures indicate that magma has cooled very slowly throughout
crystallization. _________________________
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3.
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Sandstone, with abundant quartz and orthoclase feldspar, is among the most
durable of igneous rocks. _________________________
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4.
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Valuable ore deposits are often associated with igneous extrusions.
_________________________
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5.
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Different
minerals melt and crystallize at different temperatures.
_________________________
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6.
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Igneous
rocks can be identified by their physical properties of crystal size and texture.
_________________________
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7.
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Igneous
rocks are rarely used as building materials because of their strength, durability, and beauty.
_________________________
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8.
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Diamonds are
sometimes found in igneous intrusions known as kimberlites.
_________________________
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Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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9.
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As
the water content of rock increases, the melting point ____. a. | first increases,
then decreases | c. | decreases | b. | remains the same | d. | increases | | | | |
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10.
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A
model that illustrates the predictable patterns of mineral formation from cooling magma is
____. a. | Bowen's reaction
series | c. | layered
intrusion formation | b. | crystal separation | d. | mineral composition | | | | |
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11.
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Intrusive igneous rocks form ____. a. | fine-grained rocks | b. | when a molten
mass of rocks cools quickly | c. | on Earth's surface | d. | coarse-grained
rocks | | |
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12.
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Rocks are
formed when magma ____. a. | erodes | c. | crystallizes | b. | undergoes radioactive
decay | d. | weathers | | | | |
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13.
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Igneous
rocks that cool slowly beneath Earth’s crust are ____. a. | extrusive | c. | sedimentary | b. | intrusive | d. | always magnetic | | | | |
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14.
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Igneous
rocks that cool quickly on Earth’s surface are ____. a. | extrusive | c. | metamorphic | b. | intrusive | d. | always magnetic | | | | |
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15.
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Extrusive
rocks, which cool more rapidly than intrusive rocks, are generally more ____. a. | coarsely
grained | c. | radioactive | b. | finely grained | d. | magnetic | | | | |
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16.
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Factors that
affect a rock’s melting point include ____. a. | pressure and water content | c. | rarity | b. | value as a gem | d. | usefulness as a building material | | | | |
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17.
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Valuable ore
deposits and gem crystals are often associated with ____. a. | oceans | c. | thin crustal
areas | b. | oil deposits | d. | igneous intrusions | | | | |
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Completion
Complete each sentence or
statement.
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18.
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Rock formed
from the crystallization of magma is called _________________________.
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19.
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___________________________________ illustrates the relationship between cooling magma
and mineral formation.
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20.
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A(n)
____________________ rock, such as dunite, has low silica content and very high iron and magnesium
content.
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21.
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A rock that
has grains of two different sizes has ____________________ texture.
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22.
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A(n)
____________________ is a vein of extremely large-grained minerals.
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23.
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A rare,
ultramafic rock that might contain diamonds is a(n) ____________________.
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Matching
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Match each item with the correct statement below. a. | felsic | e. | pegmatite | b. | kimberlite | f. | porphyritic | c. | lava | g. | ultramafic | d. | mafic | | | | |
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24.
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Magma
that flows out onto Earth's surface
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25.
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Light-colored rock such as granite that has high silica content
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26.
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Dark-colored rock such as gabbro that is rich in iron and magnesium
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27.
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Rock
that is very high in iron and magnesium
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28.
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Texture characterized by large, well-formed crystals surrounded by finer-grained
crystals of the same mineral
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29.
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Vein
of extremely large-grained minerals
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30.
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Ultramafic rock that can contains diamonds
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Match
each item with the correct statement below. a. | Extrusive rock | g. | Porphyritic texture | b. | Intrusive
rock | h. | Layered
intrusion | c. | Felsic rock | i. | Pegmatite | d. | Intermediate rock | j. | Kimberlite | e. | Mafic rock | k. | Zoned crystal | f. | Ultramafic
rock | | | | |
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31.
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Dark color
with low silica content; high iron/magnesium content
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32.
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Vein of
extremely large-grained minerals
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33.
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Sodium-rich
outer layers, calcium-rich core
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34.
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Coarse-grained
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35.
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Composed of
distinct bands of minerals
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36.
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Fine-grained, glassy
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37.
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Long
pipelike intrusion; may contain diamonds
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38.
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Light color
with high silica content
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39.
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Large and
small crystals in same rock
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40.
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Very dark
color with very high levels of iron/magnesium
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41.
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Medium color
with moderate silica content
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Short Answer
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42.
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How
does the geothermal gradient of continental crust differ from that of oceanic
crust?
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43.
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What
causes the difference in grain size between intrusive igneous rocks and extrusive Igneous
rocks?
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44.
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How
is partial melting related to fractional crystallization?
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45.
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A
group of igneous rocks are found. The rocks all have very low silica contents. Based on this
characteristic alone, to what group of igneous rocks do these rocks likely belong?
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Compare and contrast each pair of related terms or phrases.
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46.
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intrusive
igneous rock, extrusive igneous rock
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47.
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magma,
lava
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48.
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felsic,
mafic
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49.
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Which rock
type or feature forms when rapid cooling of magma does not allow its calcium-rich core to react
completely with the magma?
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50.
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Which rock
type or feature forms when crystallization begins slowly and then becomes rapid?
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51.
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Which rock
type or feature may be formed when magma is forced rapidly upward, creating pipelike
intrusions?
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52.
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In general,
do intrusive rocks crystallize more rapidly or less rapidly than do extrusive rocks?
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53.
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What is
partial melting? Explain how partial melting affects igneous rock formation.
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54.
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What is
fractional crystallization? Does it add or remove elements from magma? Explain your
answer.
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55.
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What
relationship does Bowen’s reaction series illustrate? What crystallization patterns did Bowen
discover in feldspars and iron-rich minerals?
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56.
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What are the
three main groups of igneous rocks? What are the characteristics of each group?
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57.
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Why would
crystals formed early in magma crystallization have larger, better-shaped crystals than those that
formed later?
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58.
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What is
porphyritic texture? What sequence of events produces porphyritic texture in rocks?
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The diagram
shows the proportions of minerals in common igneous rocks. Use the diagram to answer the following
questions.
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59.
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What four
groups of igneous rocks are shown in the diagram?
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60.
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Which rocks
are lighter in color—those on the left side of the diagram or those on the right?
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61.
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What
categories of rock grain are shown on the diagram?
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62.
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How are
silica content and color related in this diagram?
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63.
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Do the
groups of igneous rocks shown in the diagram exhibit an abrupt change from one group to another or a
continuous change from one rock type to the next? Explain your answer.
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64.
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Rock Sample
A is coarse-grained, 90 percent olivine, and 10 percent pyroxene. What is the name of the rock? What
group is it in?
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65.
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Is rock
Sample A dark or light in color?
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66.
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Rock Sample
B is coarse-grained, 25 percent quartz, 65 percent feldspar, and 10 percent unidentified minerals.
What is the name of the rock? What group is it in?
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67.
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If a rock
sample with the same mineral content as Sample B was fine-grained instead of coarse-grained, what
would its name be?
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68.
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Do
calcium-rich feldspars occur in felsic rocks or in mafic rocks?
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69.
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What is the
primary mineral component of felsic rocks? Ultramafic rocks?
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Problem
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70.
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According to the diagram below, what elements are removed from this particular magma
during fractional crystallization? What effect does this have on the overall proportions of the
remaining elements—Al, Ca, Si, O, Na, and K—in the magma?
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