Geology Exam 2

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seashell
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66675
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Geology Exam 2
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2011-02-17 13:26:24
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Geology minerals
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Material for test 2
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  1. Each mineral has a...
    and...
    Definite chemical composition; internal atomic structure
  2. Sodium Chloride (NaCl)
    Halite, tastes like salt
  3. Fe2O3
    Hematite
  4. Why study minerals?
    • fundamental building block of rocky planet
    • rock = mixture of minerals
    • form under physical & chemical conditions
    • help us understand earth processes
    • most metals originate from minerals
    • manufacturing
    • biological processes from minerals as well
  5. seashells & pearls=
    bones & teeth=
    • calcium carbonate
    • phosphate minerals
  6. most abundant element (universe, sun, humans)
    hydrogen
  7. earth's comp
    oxygen - 50, iron -17, silicon/magnesium - 14
  8. earth's crust comp
    oxygen- 47, silicon- 28
  9. earth's atmosphere comp
    nitrogen -78, oxygen - 21
  10. density =
    =mass/volume
  11. lead has high or low density
    high density mineral contains...
  12. Lead sulfide (PbS)
    Galena, heavy shiney silver metallic
  13. What is Mohs?
    Hardness scale, with log scale of absolute hardness on y axis
  14. List the 9 Mohs's hardness scale minerals
    • Diamond.Corundum.Topaz.Quartz.
    • Feldspar.Apatite.Florite.Calcite.Gypsum.Talc
  15. colors vary depending on...
    impurities
  16. Name cleavage of each mineral:
    Mica. Florite. Calcite. Quartz
    single.double.rhombihedral.none
  17. Titanium makes quartz...
    Iron makes quartz...
    • pink
    • purple
  18. Type of bond is determined by...
    ....the arrangement of electrons around the nuclei of the atoms involved
  19. ionic bond...
    electrons transfered.weaker than covalent bonds. ex NaCl
  20. covalent bond....
    eletrons shared. strongest bond. ex: carbon or water
  21. metallic bond...
    electrons roam between atoms. makes them conductive and shiney
  22. van der waals bond....
    unequal electron distribution around nuclei creates weak charge assymentry. ex "soft" minerals like talc
  23. two minerals that have both ionic and covalent bonds
    • Calcite (CaCO3)
    • Quartz (SiO3)
  24. the lopsided geometry of water gives it......which allows it to pull apart weakly bonded minerals
    polarity
  25. a mineral is....
    • naturally occuring solid
    • usually inorganic
    • defined chemical composition
    • an ordered atomic structure
  26. a mineral isn't....
    • man-made (cubic zirconia or synthetic ruby)
    • liquid or gas
    • organic compounds (like table sugar or coal)
    • amorphis or non-crystalline (obsidian, glass is amorphis and technically a very slow-flowing liquid)
  27. types of atoms =
    composition
  28. composition determines...
    • bond strength
    • atomic structure
  29. controlled by atomic structure (how mobile electrons are within the crystal to affect smoothness; reflect atomic arrangement of atoms)
    luster & crystal form
  30. contolled by comp
    density & color
  31. controlled by bond strength
    • hardness (and atomic structure)
    • cleavage
  32. controlled by hardness
    streak
  33. diamond versus carbon
    various colors, transparent, hardness 10, 3D network of C atoms, electrical insulator

    black/gray, opaque, hardness 2, sheets of C atoms, electrical conductor
  34. covalent produces a hardness of....
    7 or higher, e.g. quartz
  35. how many minerals are known in the world
    ~4000
  36. pure "as-found" minerals
    • talc
    • sulfur
    • gold
    • graphite
  37. elements that come from ore minerals
    • iron
    • lead
    • zinc
    • copper
    • nickel
    • uranium
  38. ... out of the 89 minerals make up >99% of earth's crust
    12
  39. most common in earth's crust
    • silicon
    • oxygen
  40. most common in whole earth
    • oxygen
    • iron
  41. most abundant and simple silicates
    quartz
  42. besides silicon, 4 additional elements that add to minerals
    Na, Ca, K, Al
  43. most common crustal mineral
    feldspars
  44. 3 most important iron-magnesium silicates
    olivines, amphiboles, pyroxenes
  45. ions can subsitute for other ions of similar...
    Ex: Garnets
    • size
    • charge
  46. carbonates (percipitated out of water, used for cement)
    • calcite
    • dolimite
    • aragonite
  47. oxides (metals mined and extracted)
    • hemitite
    • magnetite
  48. halides (percipitated out of water)
    halite
  49. sulfates (percipitated out of water
    gypsum
  50. sulfides (mteals mined and extracted)
    • pyrite (FeS)
    • galena (PbS)
  51. Type of rock formed from breakdown of pre-existing rocks
    sedimentary
  52. rock formed by solidification of molten rock material (magma)
    igneous
  53. rock formed by the transformation of pre-existing rocks, without melting, because of the effects of elevated pressure, temperature, hot fluid or all 3
    metamorphic
  54. ....solidify quickly at surface after erupting from volcano (form little to no crystals, often layers)
    volcanic/extrusive igneous rocks
  55. ....solidify slowly beneath the earth's surface (form large crystals slowly & massive w/out layers)
    Plutonic/intrusive igneous rocks
  56. Magma that reaches the surface while still molten is called...
    LAVA
  57. in the weathering process, fragments form....
    • clastic sedimentary rock
    • ex: sandstone
  58. in the weathering process, dissolved ions form...
    • chemical sedimentary rock
    • (also is teh cement for clastic rocks)
  59. lithification:
    • the "making of rocks"
    • 1.accumulate into beds
    • 2.compressed
    • 3.with cements percipitating, form a hardness
  60. alters the shape/orientation of the crystals
    changes some minerals into different minerals
    Metamorphism
  61. metamorphic vs sedimentary
    metamorphic vs igneous
    • meta - forms in bands (often discountinuous), with light & dark, varying in color and thickness
    • meta - has a distict and different mineralogy and no signs of melting
  62. why know igneous rocks & process?
    • locate valuable minerals
    • learn more about earth's internal processes such as plate techtonics
    • avoid hazards from volcanoes
  63. name 5 intrusive structures
    • magma chamber
    • dike (shallow errosion, cuts across layers)
    • sill (cuts horizontally between layers)
    • volcanic neck (devil's tower)
    • batholith (deeper erosion)
  64. igneous rocks are classified by...
    composition (minerals present): glassy, aphanitic, porphoritic, phanaritic

    texture (size of crystals): ultramafic, mafic intermediate, felsic
  65. where do igneous rocks form?
    • divergent boundaries/hot spots (decompression )
    • convergent boudnaries (adding water)
  66. The magma has the same composition as the original rock when....(and can recrystallize)
    the rock melts completely
  67. the relationship with temperature increase with increasing depth into earth
    • Geothermal Gradient
    • beneath continental crust: 30* C per km
    • beneath ocean crust: 60* C per km
  68. Fractional Crystalization
    early-forming crystals will either settle downward or attach to the walls where the temp is coolest and grow inward. Magma changes composition continuously.
  69. Bowen Reaction Series
  70. describe the volcano types
  71. Volcanic eruptions
  72. volcanic emissions
  73. most explosive volcano is...
    Composite (mt st helens) b/c of the gas build up
  74. gases escape more readily from ....magma
    low viscosity
  75. viscosity = resistance to flow; depends on composition
    high silica vs low silica
    • high silica = high viscosity = thicker= explosive eruptions=cascade volcanos=felsic
    • low silica = low viscosity =runnier = quite fluid flows = basalitc sheild volcanoes (hawaii) = mafic
  76. order common igneous rocks by high to low silica content/viscosity
    • rhyolite
    • dacite
    • andesite
    • basalt
  77. describe volcanic gases
    • SO2 reflect sun's energy back to space and cools the earth's temperature
    • acidic
    • contain Pb, As, Au, Hg, etc
  78. The more silicate rich the magma the .... the gas content
    higher
  79. elaborate on 8 volcanic eruptions:
    lava flow
    earthquake
    landslide/tsunami
    volcanic gases
    direct blasts
    pyroclastic flows
    lahars
    tephar/ash flows
    • Lava flows: pahoehoe vs. a’a
    • Earthquakes:
    • 1) volcano-tectonic = magma movement
    • 2) long period = volcanic tremor
    • Landslides/Tsunamis: eruption not required
    • Volcanic gases: precursor to eruption; VOG
    • Directed blast: structural weakness (Mt. St.Helens)
    • Pyroclastic flows: “nuee ardentes”; surges
    • Lahars: eruption not required;(mud/debris flow) composite volcanoes
    • Tephra/Ash fall: acute (asphyxiation) andprolonged hazard (climate change)
  80. VEI
    What VEI rating does a super volcano have?
    • Volcanic Explosive Index
    • 8
  81. Composition = extrusive/intrusive

    Name according to comp...
    • Ultramafic = very rare/peridotite
    • Mafic = basalt/gabbro
    • Intermediate = adesite/diorite
    • Felsic= Rhyolite/granite
  82. Transformation of magma:
  83. increase in pressure......melting temperatures
    • increase
    • this means rock moving upwards tends to melt
  84. felsic magma density is ....than crust density
    mafic magma density is.....than crust density
    mafic magma density is .....than MANTLE density
    • less than
    • greater than
    • less than
  85. why study sedimentary rocks?
    • contain archive of ancient history of the planet
    • preserve fossils
    • derive coal, oil & natural gas
    • open spaces btwn sedimentary layers acts as storage for water/oil/natural gas
  86. physical weathering often takes advantage of....
    • cracks
    • fractures
    • irregularities in rock
  87. many minerals readily dissolve in water, especiialy those with....bonds
    ionic
  88. chemical weather occurs 3 ways:
    • dissolution
    • hydolysis
    • oxidation
  89. most abundant clastic materials
    • quartz
    • clay
  90. calcite dissolves better ....water and comes out in ....water
    silica dissolves ....water and comes out in ....water
    • cool water; warm water
    • warm water; cool water
  91. most important mineral cements
    • calcite
    • hematite
    • quartz
    • clay
  92. Sedimentary rock classification determined by texture and composition
    Texture determines ........nomeclature.
    Composition dominates .....nomeclature.
    • Clastic (grain size, sorting, rounding)
    • Chemical
  93. freeze/thaw, root wedging, jointing
    physical weathering
  94. dissolution, hydroysis, oxyidation
    chemical weathering
  95. classification (grain size, sorting, & rounding) allow scientists to interpret....
    sediment source, weathering and erosion history
  96. clastic sediemtn texture reatlates to...
    • strength and steadiness of currents transporting the sediment
    • distance of transport
  97. 3 main types of preservation in sedimentary rocks:
    • original materials such as bones/teeth
    • minerals replace carbon-rich compounds
    • as an impression that remains in the sediment such as footprints/shell casts
  98. fossil fuels (stored chemical energy from sun) form from....
    organic matter disposited by sediments (plants/animals)

    locating fossil fuels requires a knowledge of sedimentary rocks
  99. depositional environments
    the characteristics used to name sedimentary rocks can be used to interpret the history of an area that was once a lake, beack, swamp, etc.
  100. graded beds implies....
    ripples/cross-bedding implies....
    shale layers in between indicate...
    • settling of coarse then fine particles
    • sediment being swept by waves before it settled
    • times of slow accumulation
  101. graded sandstone beds interlayered with deep water marine shale are the result of.....
    turbidity currents
  102. metamorphic rocks are found in....
    • activiely forming mountain ranges
    • always in eroded mountain belts
  103. metamorphic rocks exhibit two types of change
    • new minerals form
    • rock texture is altered
  104. raising the temperature of rock through sediment burial, tectonic burial, and magma intrusions allow the material to reach...
    metamorphic conditions
  105. high temp metamorphism causes...
    • dehydration
    • degassing
  106. mineral stability
    • mineral states are stable at a fixed range of temp and pressure
    • ex: water as a liquid, solid, gas
  107. geothermal gradient for metamorphism: temperature increases as rocks are .....in earth's crust
    buried deeper
  108. recrystallization of minerals into new ....and .....

    recrystallization changes rock texture without changing ... and ...
    • sizes
    • shapes

    • without changing:
    • chemical comp
    • mineral content
  109. describes planes of mineral formed in response to stress
    foliation
  110. the presence of ... makes metamorphic reactions occur faster and more easily.
    fluid
  111. ...are those that form in a limited range of conditions
    tell the geologist about the metamorphic conditions (b/c they're stable over a certain temp/pressure)
    index minerals

    • good:chlorite(low),amphibole, pyroxene
    • poor: quartz, feldspars, muscovite
  112. metamorphic texture is foliated or non-foliated. define....
    composition depends on ... and ...
    • foliated rocks all have layered minerals
    • parent rock and fluids
  113. Order foliated metamorphic rocks by lowest grade:
    • slate
    • phyllite
    • schist
    • gneiss
    • migmatite
  114. non-foliated metamorphic rock is named by its ..... as the primary characteristic
    composition (mineral content)
  115. most common contact metamorphic rock
    hornfels
  116. contact metamorphism: metamorphic grade is highest when it is located .....to the intrusion
    closest
  117. occurs along the boundaris of igneous intrusion and under lava flows
    heat is dominant agent
    contact metamorphism
  118. ....occurs along mid-ocean ridges/divergent plate boundaries
    involves migration and raction of hot, mineral rich geopthermal FLUIDS
    hydrothermal metamorphism
  119. ...occurs along subduction zpones and active mountain-forming zones
    ...occurs on a broad, large-scale
    ....is pressure driven
    regional metamorphism
  120. in regional metamorphism:
    low-t/high-p occurs when parallel and ....to trench
    high-t/low-p occues when parallel and ....to trench
    • close
    • farther
  121. paired metamorphic belts refere to .....metamorphism
    • regional
    • e.g. Japan
  122. protolith or parent rock transformation in metamorphic rocks:
    limestone ->
    sandstone ->
    • marble
    • granite

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