Minerals

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Minerals
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Minerals

• Earths crust is composed of about 3000 minerals.
• A mineral is a naturally occurring, inorganic
  solid with a specific chemical composition and a
  definite crystalline structure.

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Minerals

• Naturally occurring and inorganic
• Formed by natural processes
• Man-made diamonds are not minerals
• Minerals were never alive during any part of
  their existence
• Salt is a mineral
• Sugar is harvested from plants and therefore not
  a mineral
• Coal is not a mineral because it formed form
  organic processes

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Minerals

• Solids with specific compositions
• Minerals must be solids
• Solids have definite shapes and volumes, unlike
  liquids and gases
• Each type of mineral has a unique chemical
  composition

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Minerals

• Some are composed of single elements, most are
  composed of compounds
• In some minerals, chemical composition may vary
  within a certain range
• The ratio of the total amounts of each compound
  always stays the same.

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Minerals

• Definite crystalline structure
• The atoms in minerals are arranged in regular
  geometric patterns that are repeated again and
  again.
• A crystal is a solid in which the atoms are
  arranged in repeating patterns

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Minerals

• Crystallization
• Growth of a solid from a material whose atoms can
  come together in the proper chemical proportions
  and crystalline arrangement
• Form ordered, three-dimensional arrays called
  lattices.
• Form flat, planar surfaces called crystal faces

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Minerals

• Crystals
• When a mineral grows in an open space, it may
  grow into one large crystal
• The resulting mineral crystal may take the shape
  of one of the six major crystal systems
• Cubic
• Tetragonal
• Hexagonal
• Orthorhombic
• Monoclinic
• Triclinic

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Minerals

• Cubic crystals are usually cube shaped, but not
  always.
• There are many that are shaped like octahedrons
  (eight faces), and some that are shaped like
  dodecahedrons (10 faces).

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Minerals

• Tetragonal crystals are shaped like cubic
  crystals but are longer in one direction making
  shapes like double pyramids and prisms.

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Minerals

• Hexagonal crystals often look like six-sided
  prisms.
• When looked at on end, the crystal looks like a
  hexagon shape in cross section.

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Minerals

• Orthorhombic crystals are often shaped like
  rhombic prisms or dipyramids (two pyramids stuck
  together).
• They often look a bit like tetragonal crystals
  except that they are not square in cross section
  (when you look at the crystal on end).

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Minerals

• Monoclinic crystals look like tetragonal crystals
  that have been skewed.
• They often form prism shapes and double pyramids.

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Minerals

• Triclinic crystals do not fit any of the other
  types
• They are usually not symmetrical from one side to
  the other.

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Minerals

• Crystals
• The six crystal shapes are fairly rare
• More commonly, the internal atomic arrangement of
  a mineral is not so readily apparent because the
  mineral formed in a restricted space
• For any specific mineral, only one of the six
  shapes can form.

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Minerals

• Minerals from magma
• Minerals formed from the cooling of magma
• Density differences force magma upward into
  cooler layers of Earths interior the magma
  cools
• Compounds in the magma no longer move freely
  they begin to interact chemically to form
  minerals
• The type and amount of elements present in the
  magma help determine which minerals will form,
  while the rate at which the magma cools
  determines the size of the mineral crystals

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Minerals

• Minerals from solution
• A given volume of water in a solution can
  dissolve only so much of a solid before becoming
  saturated
• If a solution becomes supersaturated with another
  substance, mineral crystals may begin to
  precipitate
• Minerals can also form when elements dissolve in
  a supersaturated solution
• When liquid evaporates from the solution, the
  elements left behind may begin to arrange into
  crystals

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Minerals

• Mineral Groups
• Out of the 3000 minerals found on Earth, only
  about 30 are considered common.
• The most common are known as rock-forming
  minerals because they make up most of the rocks
  found in Earths crust

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Minerals

• Mineral Groups
• The vast majority of minerals are made of the
  eight most common elements (listed with their
  percentage)
• 46.6 Oxygen
• 27.7 Silicon
• 8.1 Aluminum
• 5.0 Iron
• 3.6 Calcium
• 2.8 Sodium
• 2.6 Potassium
• 2.1 Magnesium

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Minerals

• Six major mineral groups
• Silicates (Olivine Mg2SiO4)
• Carbonates (Calcite CaCO3)
• Oxides Hydroxides (Hematite Fe2O3 or Brucite
  MgOH2)
• Halides (Halite NaCl)
• Sulfates (Anhydrite CaSO4)
• Sulfides (Pyrite FeS2)

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Minerals

• Silicates
• Minerals that contain silicon (Si), oxygen (O),
  and one or more other elements
• Silicates make up approx. 96 percent of the
  minerals found in Earths crust
• Examples feldspar, quartz
• One silicon atom attaches to four oxygen atoms to
  form a silica tetahedron

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Minerals

• Silicates
• A tetrahedron is a three-dimensional shape
  structured like a pyramid
• The tetrahedron shape allows molecules to combine
  chemically and structurally in a vast number of
  ways, which accounts for the diversity of
  silicates

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Minerals

• Carbonates
• Minerals composed of one or more metallic
  elements with the carbonate compound CO3.
• Examples Calcite, dolomite, rhodochrosite
• Carbonates are the primary minerals found in
  limestone, coquina, and marble.

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Minerals

• Oxides/Hydroxides
• Oxides are compounds of oxygen and a metal.
• Hydroxides are compounds of hydroxide (OH) and a
  metal.
• Examples hematite, magnetite, uraninite

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Minerals

• Other groups
• Sulfides compounds of sulfur and one or more
  other elements (pyrite, foolsgold)
• Sulfates compounds of SO4 and one or more other
  elements

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Minerals

• Other groups
• Halides chloride or fluoride with calcium,
  sodium, or potassium (Halite)
• Native elements one element only (Native copper)