Rocks and Minerals

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Rocks and Minerals
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Mineralsthe building blocks of rocks

• Mineral Characteristics
• natural
• inorganic
• solid
• definite composition
• crystal structure

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Mineral Formation

• 4 major processes by which minerals form
• 1. Crystallization from magma- cooling magma
  causes minerals to crystallize

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2. Precipitation

• Minerals dissolve out of evaporated water
  precipitated

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3. Pressure and Temperature

• Change in pressure and temperature cause an
  existing mineral to recrystallize while still
  solid

Muscovite
Talc
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4. Hydrothermal Solutions

• A hot mixtures of water with substances dissolved
  in them. When they come in contact with existing
  minerals- a chemical reaction occurs forming a
  new mineral

Bornite
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Mineral Composition

• Minerals are grouped or classified based on their
  composition. There are 6 groups

• 1. Carbonates - contain carbon, oxygen, and one
  ore more metallic element

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2. Silicates

• formed from silicon and oxygen
• elements combined to form a silicon tetrahedron,
  1 silicon atom and 4 oxygen atoms
• formed from cooling magma
• either near the surface (few crystals) or deep
  below surface (larger crystals)

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3. Oxides

• - Minerals that contain oxygen and one or more
  other element(s)

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4. Sulfates and Sulfides
Gypsum

• - Minerals containing sulfur

Pyrite
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5. Halides
Halite

• -minerals containing halogen ions plus one or
  more other elements

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6. Native Elements

• Minerals that exist in a relatively pure form
• gold, silver, copper

Gold crystal structure
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Mineral Properties

• Mineral PROPERTIES are used to identify minerals
  based on specific characteristics

• Luster
• Streak
• Color
• Specific Gravity
• Cleavage Fracture
• Hardness
• Magnetism
• Fluoresence

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• Streak
• color of a mineral in its powder form

• Color
• often not a good property for Iding

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• Luster
• how light is reflected from the surface of a
  mineral

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Cleavage- tendency to break along flat, even
surfaces (mica)Fracture- uneven breakage
(quartz)
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Specific Gravity- ratio of a minerals density to
the density of water
Specific Gravity mass (g) of dry sample
mass lost in water Specific Gravity is
a ratioso Specific Gravity has no units
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Hardness- measure of resistance of a mineral
being scratched
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• Magnetism
• Magnetite

• Fluorescence

Double Refraction Calcite
Smell Sulfur
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Rocks and The Rock Cycle
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Rocks- any solid mass of mineral or mineral-like
matter that occurs naturally as part of our planet

• There are 3 major type or families or rock
• Igneous rocks
• Sedimentary rocks
• Metamorphic rocks

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Igneous Rocks

• Magma- molten material underground
• Lava- magma that reaches the surface
• Igneous rocks are formed from magma that has
  cooled and hardened either beneath the surface or
  from a volcanic eruption

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2 Ways to Form Igneous Rock

• Intrusive Igneous Rocks- form when magma hardens
  beneath Earths surface
• Magma intrudes into existing rocks

• Extrusive Igneous Rocks- form when lava hardens
  on the surface of the Earth
• Extruded onto the surface

rhyolite
granite
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• Magma contains some gases, including water vapor-
  this make it less dense, so it rises
• As magma rises, it cools and forms crystals
• The longer the cooling time the larger the
  crystals

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Classification of Igneous Rocks Igneous rocks are
classified by texture and composition

• Texture refers to the appearance of an igneous
  rock (size, shape, arrangement of crystals)
• Composition refers to the proportions of light
  and dark minerals in the rock

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• Coarse- grained Texture- form as a result of slow
  cooling, ions can move large crystal size
• Fine-grained Texture- form as a result of quick
  cooling time, ions lose motion small crystal
  size
• Glassy Texture- form from lava that cools
  rapidly, ions dont have time to arrange glassy
  texture
• Porphyritic Texture- rocks with different size
  minerals that form from varying cooling rates

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• Felsic Composition- contain mainly quartz and
  feldspar, some with biotite mica and amphibole.
  Make up major rocks of continental crust
• Mafic Composition- contain mainly dark colored
  minerals and feldspar, along with Mg and Fe.
  Darker and denser than granitic composition

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Classification of Major Igneous Rocks

• Texture is crossed with composition to classify
  igneous rocks. For example, granite has a coarse
  texture due to slow cooling and larger crystals,
  and a light color from the light colored quartz
  and feldspar minerals used to form it.

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Sedimentary Rocks- formed from compacted and
cemented sediments

• Weathering physically and chemically breaks rocks
  into small pieces called sediments

• Sediments are moved
• by wind, water, ice,
• and gravity
• Eventually, they are dropped and form layers
  that are cemented together

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Weathering, Erosion, and Deposition

• Weathering breaks rocks down
• Erosion involves weather and the removal of rock
• Deposition is the dropping of sediments

• Sediments are deposited according to size

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Compaction and Cementation

• Compaction is the process that squeezes the water
  out of the sediments. It is caused by the weight
  of the sediments.
• Cementation takes place when dissolved minerals
  are deposited in the tiny spaces among the
  sediments.

• Cementing holds the sediments together.

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Classification of Sedimentary Rocks

• Clastic Sedimentary Rocks are formed from
  weathered bits of rocks and minerals
• Organic Sedimentary Rocks are formed from living
  materials

• Chemical Sedimentary Rocks are formed when
  dissolved minerals precipitate from water
  solution

rock salt
limestone
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• Sedimentary rocks hold many clues to the Earths
  history
• Layers of sediments are records of geologic
  events on Earth
• Fossils are unique to sedimentary rocks

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Sedimentary rocks drop according to size larger
particles fall first followed by smaller particles
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Metamorphic Rocks- form when existing rocks
undergo change through heat and pressure

• Metamorphism means to change
• Most metamorphic changes occur at high
  temperatures and pressure
• These occur deep below the Earths surface and
  extend into the mantle

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Forms of Metamorphism

• Contact Metamorphism- forms when magma intrudes
  into existing rock
• Changes in rocks are minor

• Regional Metamorphism- formed during mountain
  building process that occur over a large area
• Major changes to rocks

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• Contact metamorphism

• Regional metamorphism

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Agents of Metamorphism

• Heat- causes existing minerals to recrystallize
  or new minerals to form
• Pressure- causes the spaces between mineral
  grains to close more compact rock greater
  density

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Classification of Metamorphic Rocks- based on
texture and composition

• Foliated Metamorphic Rocks- form when minerals
  recrystallize at right angles to the direction of
  force
• Causes a layered or banded appearance

• Nonfoliated Metamorphic Rocks- no banded texture
• Most contain only one mineral

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• Foliated

• NonFoliated

slate
marble
schist
gneiss
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The Rock Cycle
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The Rock Cycle

• Thinking about relationships among the major rock
  groups

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Major Rock Groups

• Igneous
• Formed from a melt (molten rock)
• Plutonic (intrusive)slow cooling and
  crystallization
• Volcanic (extrusion) quick cooling at the surface

• Sedimentary
• Formed at the Earths surface
• Clastic (Mineral Fragments or grains, clays)
• Chemical (crystalline chemical/biochemical
  precipitates)
• Organic (made from living material shells,
  plants)

• Metamorphic
• Changed by pressure, heat and fluids.

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Fig. 2.9
MAGMA
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IGNEOUS
Crystallization
MAGMA
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IGNEOUS Intrusive/Plutonic
Crystallization
MAGMA
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Extrusive/Volcanic IGNEOUS Intrusive/Plutonic
Crystallization
MAGMA
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Weathering
Extrusive/Volcanic IGNEOUS Intrusive/Plutonic
Crystallization
MAGMA
Uplift
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SEDIMENT
SEDIMENT
Weathering
Extrusive/Volcanic IGNEOUS Intrusive/Plutonic
Crystallization
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Extrusive/Volcanic IGNEOUS Intrusive/Plutonic
SEDIMENTARY
Crystallization
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Extrusive/Volcanic IGNEOUS Intrusive/Plutonic
SEDIMENTARY
Crystallization
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Extrusive/Volcanic IGNEOUS Intrusive/Plutonic
SEDIMENTARY
Increased PT
METAMORPHIC
Crystallization
Burial
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Add the Shortcuts
Extrusive/Volcanic IGNEOUS Intrusive/Plutonic
SEDIMENTARY
Increased PT
METAMORPHIC
Crystallization
Melting
Burial
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Extrusive/Volcanic IGNEOUS Intrusive/Plutonic
SEDIMENTARY
Increased PT
METAMORPHIC
Crystallization
Melting
Burial
MAGMA
Uplift
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Erosion
SEDIMENT
Weathering
Transport
Deposition
Extrusive/Volcanic IGNEOUS Intrusive/Plutonic
SEDIMENTARY
Increased PT
METAMORPHIC
Crystallization
Melting
Burial
MAGMA
Uplift
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In Conclusion

• The rock cycle demonstrates the relationships
  among the three major rock groups
• It is powered by the interior heat of the Earth
• As well as earths momentum and
• The energy from the sun
• It involves processes on the Earths surface as
  well as the Earths interior
• It connects the hydrologic cycle with the
  tectonic cycle.

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ROCK CYCLE

• The surface of the Earth is made of rock
• ROCK is a collection of one or more minerals,
  mixed together into a solid substance

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Rock Cycle

• The Series of processes in which rock forms and
  changes from one type to another by geological
  processes.

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PROPERTIES OF ROCKS

• BOWENS REACTION SERIES The pattern that shows
  how minerals form crystals when they cool based
  on their chemical make-up and melting point

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The Rock Cycle

• Melting Intrusion
• Solidification of melt
• Mountain Building
• Uplift Exposure
• Weathering
• Erosion Transport
• Deposition Burial
• Metamorphism
• Melting Intrusion

Fig 4.9
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The Rock Cycle

• Convergent Plate Boundary
• Subducting slab
• Mantle melting
• Bouyant rise of melt

Fig 4.9
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The Rock Cycle

• Convergent Plate Boundary
• Solidification of melt
• Volcanic activity

Extrusive rocks
Intrusive rocks
Fig 4.9