Geology Test 1 Hawkins – Flashcards
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What are the 5 things a mineral must be?
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1. solid 2. inorganic 3. natural 4. crystal-like patterns 5. specific chemical composition
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Most minerals are made from a combination of 8 elements...
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1. Silicon (Si) 2. Oxygen (O) 3. Aluminum (Al) 4. Magnesium (Mg) 5. Iron (Fe) 6. Sodium (Na) 7. Potassium (K) 8. Calcium (Ca)
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If a mineral has Si and O, it is called...
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silicate mineral
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The __________ is the base for all silicates.
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tetrahedral
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Silicate tetrahedral has a charge of...
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-4
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What two elements make up the silica tetrahedral?
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silica and oxygen
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Fe
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Iron +2
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Mg
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Magnesium +2
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Al
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Aluminum +3
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K
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Potassium +1
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Na
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Sodium +1
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Ca
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Calcium +2
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What are the two main groups of minerals?
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Silicates and Non-silicates
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6 classes of non silicate minerals...
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1. Oxides 2. Sulfides 3. Carbonates 4. Sulfates 5. Halides 6. Phosphates
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2 types of silicates?
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Ferromagnesian and nonferromagnesian
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polymorphism
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same chemical composition but different crystal structures
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3 categories of intrusive rocks...
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1. Phaneritic 2. Aphenitic 3. Porphyritic
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phaneritic (coarse grain)
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visible crystals deeper in the earth cools slowly
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aphanetic (fine grain)
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no visible crystals closer to surface cools fast
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porphyritic
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combination of phaneritic and aphanetic
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Two categories of extrusive rocks...
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1. Glassy 2. Vesicular
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Glassy
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cools extremely rapidly
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Vesicular
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fast cooling, gases are escaping
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How does magma form?
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from the rocks that existed before hand
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Viscosity
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resistance to flow
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high viscosity
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thick and stiff (lots of tetrahedrals)
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low viscosity
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thin and runny ( not a lot of tetrahedrals)
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Example of a deep intrusion
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plutons
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Deep intrusion with surface exposure greater than 100 km
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batholiths
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Deep intrusion with surface exposure less than 100 km
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laccoliths and stocks
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Shallow intrusions
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dikes and sills
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dike vs sill
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dikes- cut across sills- fill
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Definition of volcanic neck
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shallow intrusion formed when magma solidifies in throat of volcano
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Definition of xenolith
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rock fragment which becomes enveloped in a larger rock during crystallization of the encapsulating rock (xenolith is older compared to surrounding rock)
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What is a diapir?
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rising blob of magma
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What type of cleavage does muscovite have?
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basil cleavage
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Which of the following is NOT a mineral? a. quartz b. diamond c. petroleum d. gold
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c. petroleum
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In nature most examples of minerals do NOT grow as large, well-formed, euhedral crystals. T/F
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True
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The color of a mineral in powdered for is termed _______. a. color b. specific gravity c. luster d. streak
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d. streak
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With regard to minerals, hardness refers to _________. a. the ability to resit breaking when being struck with a hammer b. the ability to resist being scratched by other substances c. the ability to resist chemical reactions with other substances d. an absence of cleaving
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b.
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Cleavage in minerals refers to _______. a. a tendency to break in an irregular pattern b. a tendency to break along planes of weakness c. the sharpness of edges between crystal faces d. the development of distinct crystal faecs
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b.
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All other factors being equal, intrusive rocks that form deep within Earth ________ than intrusive rocks that cool near the surface. a. are more felsic b. contain a smaller proportion of volatiles c. cool more slowly d. cool more rapidly
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c.
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Which type of magma has the greatest silica content? a. felsic b. intermediate c. mafic d. ultramafic
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a.
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If a body of magma becomes more felsic, its viscosity will ______. a. increase b. decrease c. stay the same
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a.
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Viscosity depends on ____________. a. temperature b. volatile content c. silica content d. all of the above are correct
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d.
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In Bowen's discontinuous reaction series, the first mineral to crystallize from a mafic melt is ______. a. olivine b. plagioclase c. pyroxene d. quartz
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a.
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When magma crystallizes, ________ are formed. a. intrusive igneous rocks b. extrusive igneous rocks c. volatiles d. pyroclastic debris
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a.
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Bowen's continuous reaction series describes the crystallization behavior of a single mineral _________. a. olivine b. plagioclase c. pyroxene d. quartz
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b.
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A dike intruding the surface would most likely have what texture? a. phaneritic b. aphanitic c. porphyritic d. andesitic
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b.
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A pluton would most likely have what igneous texture? a. phaneritic b. aphantic c. porphyritic d. andesitic
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a.
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Igneous rocks are named by composition and _______. a. number of minerals present b. don't pick me c. texture d. gas content
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c.
