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					                 Minerals
•***A mineral is a naturally occurring, inorganic,
solid with a crystalline structure and a consistent
            chemical composition***.
The 5 Characteristics of a Mineral
    •Naturally occurring - can’t be man made (no
        synthetics such as cubic zirconium)
    •Inorganic - not made from living organisms
Biotite
                   •Solid - No molten rock
     5 Characteristics Continued…
•Crystal Structure - elements arrange in a regular
and predictable pattern.
•Chemical composition - minor variations allowed



                             3-D Structure
                             of a diamond
     Fundamental Atomic Theory
• Elements cannot be broken down by chemical
  processes.
• Atoms are the basic component of an element.
• Atoms are composed of a nucleus containing
  protons and neutrons, with an electron cloud
  surrounding.
 Fundamental Atomic Theory cont...
• Ions: Atoms that have lost or gained an electron and
  are now charged.
• Cation: Lost an electron, positive (+) charge.
• Anion: Gained an electron, negative (-) charge.
• Minerals form by combinations of atoms and ions
  held together by bonds.

           Halite - rock salt
        Mineral Identification
• Physical Properties: Run tests on the
  physical characteristics of the sample.
• Crystal Structure: Shape of the sample.
• Chemical Properties: Reaction to acid,
  taste, or smell.

                         $40000.00 Diamond
                         Studded IPod Shuffle.
          Physical Properties
• Luster: How the mineral reflects light.
• Is it Metallic (M), or Nonmetallic (NM)?
      Physical Properties cont.
• Hardness: Resistance to
  abrasion.
• Moh’s Hardness Scale
• 1 - softest mineral (talc)
• 10 - hardest mineral (diamond)
• Fingernail - 2.5
• Penny - 3.5
• Glass - 5.5
• Steel Nail - 5.5
• Streak plate - 6.5
                        Breakage
• Does the mineral break along flat surfaces?




No - uneven breakage,
Fracture (F)               Yes - mineral splits along
                           parallel planes, Cleavage ( C )
(ex. Quartz)
                           (ex. Halite)
       Phys. Properties Cont.
• Streak: Color in powdered form.
  – Scrape the sample across the streak plate, what
    color is left behind?
• Specific Gravity (density): Weight of the
  mineral compared to an equal volume of
  water.
• Color: LEAST RELIABLE physical
  property.
                 Crystal Shape
  • The arrangement of ions in the atomic
    structure determines the crystal shape.



             Hexagonal      Trigonal
Isometric                              Tetragonal
             Ex. Corundum   Ex.
Ex. Pyrite                  Hematite   Ex. Zircon
               Crystal Shape cont.

Orthorhombic        Monoclinic    Triclinic
Ex. Topaz           Ex. Kunzite   Ex. Amazonite
            Other Properties…
•   Magnetism
•   Taste
•   Odor
•   Feel
•   Reaction to acid
•   Refracts Light
     Rock Forming
       Minerals
• Silicates are the largest group
  of minerals.
• Make up 95% of the Earth’s
  crust.
• Contain silicon and oxygen.
• Silicon - Oxygen tetrahedron,
  SiO4
   – Each Si is surrounded by 4
     Oxygen
   – Strong bonds, high hardness.
      Important silicate minerals
•   Feldspars: 50% of Earth’s crust
•   Quartz: Abundant in Continental crust
•   Pyroxenes and Amphiboles
•   Micas
•   Olivine: Rare in Continental crust
                     Ore Minerals:
                     Mined for metals or
                     other materials




Gems: Used for
their looks.
Example) Jewellery

				
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posted:12/30/2011
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