Minerals

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Minerals

• Chapter 8

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Minerals

• "A mineral is an element of chemical compound
  that is normally crystalline and that has been
  formed as a result of geological processes"
  (Nickel, E. H., 1995). 
• Minerals are naturally-occurring inorganic solid
  that has a specific chemical composition and
  crystal structure  

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Minerals

• 2500 Different Minerals
• 100 Considered Common Minerals
• Fewer than 20 (most common) considered rock
  forming minerals

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Eight elements make up 98 percent of Earths
Crust
Oxygen 46.6 Silicon 27.7 Aluminum 8.1
Iron 5.0 Calcium 3.6 Sodium 2.8
Potassium 2.6 Magnesium 2.1 Others 1.5
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Mineralogist

• A scientist who studies minerals including
  rock-forming minerals

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Characteristics of Minerals

• Occurs naturally in the Earth
• Inorganic-not formed from living or once living
  things
• Solid

• Specific chemical composition
• Atoms arranged in a definite repeating pattern

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Minerals

• Crystals are a solid that have regular shape and
  flat sides called faces
• A Geode is a hollow rock that is lined with
  crystals.

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Crystal Shapes

• Tetragonal

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Crystal Shapes

• Cubic

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Crystal Shapes

• Hexagonal

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Crystal Shapes

• Orthorhombic

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Crystal Shape

• Monoclinic

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Crystal Shape

• Triclinic

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Uses of Minerals
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Ores

• Minerals from which metals and nonmetals can be
  removed in usable amounts
• Gold

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Malleability

• The ability of a substance to be hammered into
  thin sheets without breaking

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Ductility

• Ability of a substance to be pulled into thin
  strands without breaking

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Smelting

• Process during which ore is heated in such a way
  that metal can be separated from it

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Gems

• Gems are 1) Rare 2) Durable
• 3) Beautiful

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Precious Stones

• Rarest and most valuable

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Semi-Precious Stones

• Not as Rare and Valuable
• Hardness of less than 7

Opal
Garnet
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Mineral Identification

• Minerals can be identified by their color and
  texture

Beryl-Emeralds
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Color

• Easily observed, however many minerals come in a
  variety of colors and some are colorless in
  addition, the color of minerals can change as a
  result of exposure to or treatment with heat,
  cold, pollution or radiation

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Texture

• The way a mineral feels.(greasy, earthy, etc.

Talc
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Luster

• Describes the way the mineral reflects light from
  its surface
• Two types-Metallic and Non-metallic

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Metallic Luster

• Chalcopyrite
• Metallic Luster

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Nonmetallic Luster

• Kaolinite
• Non-Metallic Luster

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Vitreous

• Vitreous-Glassy

Tourmaline
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Pearly

• Looks like the shiny quality of pearls

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Greasy

• Sun tan oil look

Graphite
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Silky

• Shines like silk

Schorl
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Adamantine

• Brilliant, like a cut diamond

The Hope Diamond
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Hardness

• Minerals ability to resist being scratched

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Mohs Hardness Scale

• Talc 1
• Gypsum 2
• Calcite 3
• Fluorite 4
• Apatite 5
• Feldspar 6
• Quartz 7
• Topaz 8
• Corundum 9
• Diamond 10

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Field Hardness Test

• 1 Easily scratched by fingernail
• 2 Scratched by fingernail
• 3 Easily scratched by a house nail Will
  not scratch a copper penny
• 4 Easily scratched by nail
• 5 Difficult to scratch with nail Will
  not scratch glass

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Field Hardness Test (cont.)

• 6. May barely scratch glass will not scratch
  steel file
• 7. May barely scratch steel file Will
  scratch glass
• 8-10. Easily scratches a steel file

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Streak

• Color of the powder scraped off a mineral when it
  is rubbed against a streak plate
• Streak Plate-an unglazed piece of porcelain

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Density

• Mass per Unit Volume

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Specific Gravity

• Ratio between the Mass of a mineral and the Mass
  of an equal volume of water

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Cleavage

• Occurs when a mineral splits along smooth,
  definite surfaces

Calcite Cleavage
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Fracture

• Conchoidal Fracture-Curved Like a Rainbow

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Fracture

• Hackly Fracture-Uneven, like broken glass

Anhydrite
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Fracture

• Splintery or Fibrous Fracture-Breaks into fibers

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Special Properties

• Double Refraction-Causes a beam of light to be
  split in two, producing a double image

Calcite
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Special Properties

• Magnetism-Acts like a weak magnet

Magnetite
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Special Properties

• Fluorescence- Mineral glows under UV light

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Special Properties

• Phosphorescence-Release of visible light,
  resulting from the absorption of UV light

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Special Properties

• Radioactivity-Release of energy by certain
  elements due to the decay of an atom into a
  lighter nucleus

Uraninite
Metatorbernite
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Mineral Groups
Silicates-Made of Oxygen and Silicon-Orthoclase Sulfates-Made of Oxygen and Sulfur- Barite Oxides-Made of oxygen and usually a Metal-Hematite
Halides-Made of Chlorine or Fluorine and Sodium, Potassium, or Calcium Carbonates-Made of Carbon and Oxygen-Dolomite
Halite
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Mineral Examples


Azurite
Graphite
Sapphire
Sulfur
Malachite