Chapter 3:Minerals of the Earth

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Chapter 3Minerals of the Earths Crust

• Mineral-A naturally formed inorganic solid that
  has a definite crystalline structure. Rocks are
  composed of minerals. Contain one or more of 92
  elements.
• Element-A pure substance that cannot be broken
  down into a simpler substance.
• Native Element -A mineral that is composed of
  only one element.
• Compound-A substance composed of two or more
  elements that have been chemically combined.

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Minerals are classified by their chemical
composition

• Silicate Minerals -minerals composed of silicon,
  oxygen and other elements and make up 90 of the
  Earths crust.
• Nonsilicate Minerals -minerals that do not
  contain silicon and oxygen.
• a. Carbonates contain carbon and oxygen.
• b. Sulfides contain one or more elements
  combined with sulphur.
• c. Sulfates contain sulphur and oxygen
  in the form of SO4.
• d. Native Elements
• e. Oxides Contains elements combined
  with oxygen.
• f. Halides Compounds such as salt (NaCl)
  that are used in industry.

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Properties

• Are characteristics that describe a mineral such
  as color, luster, streak, etc.
• Color The appearance of a mineral based
  upon the contained impurities.
• Luster - The manner in which a minerals
  surface reflects light.
• Streak The color of the powdered mineral
  left behind when rubbed against an unglazed
  porcelain tile.
• Cleavage The tendency of a mineral to
  break along smooth, flat surfaces.
• Fracture The tendency of a mineral to
  break unevenly along curved or irregular surfaces.

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Properties (cont.)

• Hardness A minerals resistance to being
  scratched.
• Density The measure of the amount of matter
  in a given space the ratio of the mass to the
  volume. DM/V.
• Special Properties Characteristics that are
  particular to only a few types of minerals.
• Fluorescence Certain minerals will glow when
  viewed with an ultraviolet light.
• Magnetism Some minerals are natural magnets.
  Ex. Magnetite a.k.a. loadstone.
• Radioactivity Some minerals can contain
  elements that give off radiation. Ex. Radium,
  Uranium.

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The Formation of Minerals

• Evaporating Salt Water as water evaporates,
  minerals such as halite and gypsum are left
  behind.
• Surface Groundwater can carry dissolved
  minerals into bodies of water where they
  crystallize to form new minerals.
• Heat Pressure can change the chemistry of the
  existing rocks to form metamorphic rocks.
• Hot Water Solutions occur when ground water
  sinks deeper to be heated by magma and react with
  minerals.
• Pegmatites teardrop shaped bodies with large
  crystals that form as magma moves upwards.
• Plutons magma that moves upwards then cools to
  form crystals.

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Mining The removal of rocks and minerals from
the Earth.

• 1.) Ore A naturally occurring mineral that is
  mined for profit.
• 2.) Surface Mining Removing deposits that are
  close to the surface in open pits or quarries.
• 3.) Subsurface Mining Removing minerals that
  are located very deep within the Earth.
• a.) Reclamation The process in
  which the surface land is returned to its
  original, pre-existing state after mining has
  been completed.
• 4.) Recycling The reuse of mined products to
  reduce our mineral needs.

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Classes of Minerals

• Metallic Minerals Minerals that have shiny
  surfaces and are good conductors of heat and
  electricity.
• Nonmetallic Minerals Minerals that are
  nonmetals, dull and are electrical insulators.
• Gemstones A type on nonmetallic mineral that is
  highly valued for its beauty and rarity. The
  color of a gemstone is its most important and
  attractive characteristic.
• Caret A unit of mass for a gemstone.
• 1 caret 200mg.