Minerals and Rocks

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Minerals and Rocks
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What is a Mineral

• A mineral is a natural, inorganic solid that has
  a characteristic chemical composition, an orderly
  internal structure, and a characteristic set of
  physical properties.

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Is it a Mineral

• Scientists ask four basic questions to determine
  if a substance is a mineral.
• Is the substance inorganic?
• Coal is not a mineral because
• it is formed from the remains
• of living things.
• Fossils are not minerals.

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Is it a Mineral?

• 2. Does it occur naturally?
• Brass is a man made alloy
• made from copper and zinc.
• Bronze is a man made alloy
• of copper and tin.
• Steel is a man made alloy of
• iron and carbon.

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Is it a Mineral

• 3. Is the substance a solid in
• crystalline form?
• A crystal is a solid whose atoms, ions or
  molecules are arranged in a regular, repeating
  pattern.
• Obsidian (volcanic glass) is not a crystal
  because its atoms are not arranged in a set
  pattern.

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Is it a Mineral

• 4. Does the substance have a consistent chemical
  composition?
• Basalt can have a variety of substances in its
  composition. Therefore it is not a mineral.

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Kinds of Minerals

• Earth scientists have identified more than 3,000
  minerals.
• However, fewer than 20 minerals are common.
• These minerals are called rock-forming minerals.
• 10 minerals are so common that they make up 90
  of the Earths crust!

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The Top 10 Minerals

• These 10 minerals are

Muscovite
Quartz
Orthoclase
Biotite
Plagioclase
Calcite
Dolomite
Ferromagnesium
Halite
Gypsum
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Silicates and Nonsilicates

• All minerals can be classified into two groups
  silicates and nonsilicates.
• Silicates contain a combination of silicon and
  oxygen. Quartz contains only silicon and oxygen.
• The most common silicates besides quartz are
  called feldspars.

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Feldspars

• Feldspars are silicates that contain silicon,
  oxygen and one or more other elements.
• The type of feldspar that forms depends on which
  metal combines with silicon and oxygen.
• If the metal is Potassium (K) then orthoclase is
  formed.
• If the metal is sodium (Na), calcium (Ca) or both
  then plagioclase forms.

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Ferromagnesian Minerals

• In addition to quartz and feldspars,
  ferromagnesian minerals-which are rich in iron Fe
  and Magnesium Mg are silicates.
• These minerals include olivines, pyroxenes,
  amphiboles and biotites.

Olivenes
Pyroxene
Biotite
Amphibole
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Silicates

• Silicate materials make up 96 of the Earths
  crust.
• Feldspar and quartz make up 50 of the Earths
  crust.

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Nonsilicate Minerals

• Approximately 4 of the Earths crust is made up
  of nonsilicate materials.
• The six major groups of nonsilicate materials
  include carbonates, halides, native elements,
  oxides, sulfates and sulfides.

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Nonsilicate Elements
Carbonate (CO3) Dolomite
Halite (Fl or Cl) NaCl table salt
Native Element Elements uncombined with other
elements such as gold or silver.
Oxides (Oxygen another element besides
silicon) Corundum which is found in rubies and
sapphires
Sulfides (S one or more other elements) Galena
PbS
Sulfates (SO4) Gypsum
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What is a Rock

• Rock is the material that makes up the solid
  parts of the Earth.

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What Makes a Rock

• Rock can be a collection of one or more minerals,
  or rock can be made up of solid organic matter.
• Sometimes rock is made up of mineral matter that
  is not crystalline such as glass.

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Igneous Rock

• The word igneous means from fire.
• Igneous rocks are formed when magma cools or
  hardens.
• Magma is molten rock.
• When exposed to the Earths surface, magma is
  called lava.

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Erosion and Rocks

• Erosion breaks down rocks into small fragments.
• Sediment is rock, mineral crystal or organic
  matter that has broken into fragments.
• Sediment is carried away and deposited by water,
  ice and wind.

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Sedimentary Rock

• When sediment deposits are compressed or cemented
  together and harden, sedimentary rock forms.

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Metamorphic rock

• Rocks exposed to tremendous pressure, extreme
  heat and chemical processes also change the form
  of existing rock.
• The rock that forms when existing rock is altered
  is metamorphic rock.
• Metamorphic means changed form.

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The Rock Cycle