UNIT 9 TOPIC 11 IN REVIEW BOOK

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UNIT 9TOPIC 11 IN REVIEW BOOK

• ROCKS, MINERALS NATURAL RESOURCES

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I. Minerals

• Minerals are the building blocks of rocks!
• A mineral is a naturally occurring, inorganic
  solid with identifiable characteristic properties.

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A. Properties of Minerals

• Color
• the most obvious and least reliable property.

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2. LUSTER

• The way in which a mineral reacts to light
• Metallic
• shines like a metal
• Nonmetallic
• Can be glassy, dull, earthy, pearly

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3. HARDNESS

• A measure of a minerals ability to scratch or be
  scratched
• The reference most used is glass with a hardness
  value of 5

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• Hardness is the most reliable identifying
  characteristic

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4. CLEAVAGE/FRACTURE

• If a mineral breaks along a plane of weakness,
• it shows cleavage and
• will have one or more smooth, flat surfaces

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• If a mineral does not have a plane of weakness,
• it will break irregularly and
• have one or more jagged edges

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5. STREAK

• The color of the powdered form of a mineral
• It is determined by rubbing the mineral on an
  unglazed porcelain plate

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Rock-forming Minerals

• The 20 to 30 common minerals that make up most
  rocks
• The most abundant rock-forming minerals belong to
  the
• silicate group

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Silicates

• Are made up of the elements
• silicon and
• oxygen
• in some combination

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• Silicon and oxygen bond together with a structure
  called a
• silicon-oxygen tetrahedron

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• The physical properties of a mineral are due to
• the internal arrangement of atoms

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II. ROCKS

• A rock is any naturally formed solid on Earth or
  in the Universe.
• Rocks are distinguished and identified based on
  their composition and texture

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• The texture of a rock is the size, shape and
  arrangement of the materials that comprise it

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• Rocks are made up of one or more minerals.
• Monomineralic rocks are made up of only one
  mineral
• Polymineralic rocks are made up of two or more
  minerals

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• Rocks are classified based upon
• how they are made
• their origin

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• There are three types of rocks
• Sedimentary
• Metamorphic
• Igneous

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A. SEDIMENTARY ROCKS

• 1. Most are made of solid fragments of sediments
  (called clasts) that have been weathered from
  other rocks and are called clastic sedimentary
  rocks

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• These rocks form from an accumulation of
  sediments on or within the top few kilometers of
  Earths crust. They are classified based upon the
  size of their sediments

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• These sediments combine to create rocks through
• burial, compaction, and/or cementation

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• Minerals such as calcite, quartz and/or hematite
  are the common cements holding sediments together

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• 2. Some sedimentary rocks are made of intergrown
  or interconnecting mineral crystals and are
  called crystalline sedimentary rocks

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• These rocks form when the minerals dissolved in
  water precipitate or evaporate out of solution
  forming a crystalline mass

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• 3. An organic, sedimentary rock is formed by
  living organisms or is mostly composed of
  materials from life forms
• example fossils!

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B. METAMORPHIC ROCKS

• Rocks that form from changes in previously
  existing rocks due to exposure to heat and
  pressure (without melting)

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• The process through which the changes occur is
  called metamorphism.
• These changes typically occur within the
  lithosphere many kilometers beneath the surface

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• The resultant rock is generally less porous and
  more dense than the original rock (parent rock).
  
• They also have larger, or distorted crystals and
  frequently show a layering of mineral crystals
  called foliation

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• Metamorphic rocks are classified and identified
  based on composition and texture

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• 1. Contact metamorphism occurs when older
  (pre-existing) rocks come into contact with the
  magma of an intrusion or the lava of an extrusion

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• At zones of contact metamorphism there is a
  gradual progression from the igneous rock to
  metamorphic rock to parent rock without clear
  separations.

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• Metamorphic rocks such as hornfels, marble and
  quartzite are formed at these zones. Because heat
  is dominant over pressure, these rocks usually
  are not foliated

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• 2. Regional metamorphism occurs when sections of
  the lithosphere (called plates) converge, the
  rocks are exposed to high temperatures and
  pressure causing mountain-building and resulting
  in the creation of metamorphic rocks

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C. IGNEOUS ROCKS

• Igneous rocks are rocks that form when natural,
  molten rock-forming material cools into a solid.

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• Magma is liquid rock beneath the surface of the
  earth
• Magma becomes lava when it exits onto the earths
  surface

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• Igneous rocks were the first rock type to form
  because the earth was mostly molten at its
  formation.

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• All igneous rocks are the result of
  solidification.
• Depending upon the location (and therefore, the
  rate) of solidification crystals of varying sizes
  may form.

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• The size of the crystals formed is directly
  dependent on the amount of time the molten
  material takes to cool.
• The longer the period of cooling, the larger the
  crystals

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1. Intrusive Igneous Rocks

• An igneous rock is intrusive (plutonic) when the
  magma cools beneath the surface of the earth.

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• Intrusive igneous rocks cool slowly due to the
  temperature and pressure beneath the earths
  surface providing ample time for the formation
  of crystals.
• These rocks are characterized by large,
  intergrown crystals easily visible to the human
  eye

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2. Extrusive Igneous Rocks

• A rock is extrusive (volcanic) when the magma
  cools at or near the surface of the earth.

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• Extrusive igneous rocks cool very quickly due to
  the lower temperature and pressure of the earths
  surface providing little time for crystal
  formation

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• These rocks have very small crystals and are said
  to have a fine texture or
• they have no crystals at all and are said to
  have a glassy texture

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• Many of the extrusive rocks formed from lava
  flows or volcanoes have rounded openings formed
  around trapped, expanding gases.
• They are said to have a vesicular texture

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Identifying Igneous Rocks

• Igneous rocks are identified on the basis of
  texture and percent mineral composition

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TEXTURE

• based on size of crystals the rate of cooling
• Coarse large, visible crystals intrusive
• Fine small, indiscernible crystals extrusive
  (near the surface)

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• Glassy no crystals at all looks like glass
  extrusive (at the surface)
• Vesicular contains air pockets from escaping air
  often compacted volcanic ash extrusive (at the
  surface)

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MINERAL COMPOSITION

• FELSIC igneous rocks high in Aluminum and
  Silicon
• Quartz and Potassium Feldspar are the key
  minerals
• Tend to be light in color and low in density

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• MAFIC igneous rocks high in Iron and Magnesium
• Pyroxene, Olivine and large amounts of
  Plagioclase Feldspar are the key minerals
• Tend to be dark in color and high in density

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BRECCIA
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CONGLOMERATE
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SANDSTONE
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SHALE
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SLATE
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SCHIST
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MARBLE
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GNEISS
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GNEISS
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OBSIDIAN
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GRANITE
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GRANITE
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BASALT
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GABBRO
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GABBRO
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SCORIA
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SCORIA
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III. Rocks and Environment of Formation

• The type of environment in which a rock is formed
  can be inferred from its composition, structure
  and texture

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• Large, thick areas of rock salt in western NYS
  lead us to the inference that, in that region,
  there was a large, shallow area of salty water
  that has evaporated

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• The bent and twisted rock structure of the
  surface metamorphic rocks of the Adirondack
  region in northern NYS indicate that this region
  once experienced one or more periods of mountain
  building processes

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• as well as uplift and erosion that exposed the
  rocks that formed deep beneath the surface

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• Sharp, angular sediments in a clastic sedimentary
  rock indicate that the rock was formed close to
  where the sediments were created. They also
  indicate that the area may have been covered by a
  glacier

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• Smooth and well rounded sediments in a clastic
  sedimentary rock indicate that the rock formed
  far from where the sediments were created.
  Long-distance transportation of sediments round
  and smooth them.

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IV. THE ROCK CYCLE

• A model that indicates the method of formation as
  well as the interconnectedness of each type of
  rock

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• Any rock can be changed into any other rock type.
• There is no preferred direction of movement
  around the rock cycle
• There is no exact point of separation between the
  rock types

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• The driving forces of the rock cycle are
• energy from the earths interior
• insolation from the sun
• gravity

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• These forces create the processes of uplift,
  erosion, weathering, pressure and high
  temperatures

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V. NATURAL RESOURCES

• Natural resources are the things that people need
  that come from the earth.
• Such as water to drink, air to breathe, plants
  to eat and use for shelter, animals to provide
  food and clothing, energy

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A. Renewable Resources

• Those resources that can be replaced by natural
  processes at a rate that is approximately equal
  to the rate at which they are used
• Resources that are replaceable within a human
  lifetime

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• Although renewable resources may not run out,
  their usage may be limited by how quickly the
  resource is created

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• Examples drinking water, plants, trees, soil,
  oxygen, fish, electromagnetic energy from the sun

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B. Nonrenewable Resources

• Resources that exist in fixed amounts. If they
  are formed in nature, they are formed so slowly
  that their use will decrease their availability.
• They are not replaceable within a human existence

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• There is a limited supply of these resources.
• Examples minerals, rocks, metal ores, fossil
  fuels.

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• Fossil fuels include oil/petroleum, natural gas,
  coal and oil shale
• and are the result of the compaction and organic
  chemical changes in large deposits of organic
  sediments which are the remains of dead plants
  and animals

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Mineral characteristics and their use

1. Quartz vibrates in a regular fashion making it
   useful in watches
2. Minerals with a high hardness are used in jewelry
   and as abrasives.

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1. Talc is very soft and has cleavage in one
   direction making it easily powdered and feel
   smooth. This makes it used in cosmetics and baby
   and foot powders.

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1. Graphite is very soft with a black streak making
   it useful as the main ingredient in pencil lead
2. Hematites red color was been used in cave
   paintings and is used in cosmetics and red paints

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Rock characteristics and their use

1. Slate is impermeable and breaks along foliations
   to produce thin, flat pieces to be used for
   roofing and chalkboards

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1. Basalt resists crushing so it is used as a base
   under roads and railroad tracks.
2. Pumice has natural pore spaces and a low density
   making it useful as a building insulator and an
   exfoliator!

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1. Granite and quartzite are very resistant to
   weathering so they are used as building stones.
2. Coal can burn and produce energy

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Rock characteristics and landscapes

• Areas high in limestone and dolostone often have
  numerous caves and sinkholes due to their ability
  to be easily dissolved and weathered. The
  weathering of limestone produces nonacidic soils
  good for crops.

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• Regions high in shale often have low topography
  with a rolling landscape and gentle slopes
  because shale weathers and erodes easily.

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• Regions high in gneiss and granite are
  structurally sound allowing for the development
  of high-rise buildings and sky-scrappers.

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THE END!