Minerals

1
Minerals

• By Ms. Parrish

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Earths Main Elements

• Oxygen
• Silicon
• Aluminum
• Iron
• Calcium
• Sodium
• Potassium
• Magnesium

• O
• Si
• Al
• Fe
• Ca
• Na
• K
• Mg

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A mineral must satisfy four conditions.

• 1. It must be an orderly arranged crystalline
  solid.
• 2. It must occur naturally
• 3. It must be inorganic
• 4. It must have a definite chemical composition.

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Crystalline Substance-

• A crystalline substance is one in which atoms are
  arranged in repeating orderly patterns.

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Crystal-

• A crystal is a homogeneous solid that is also a
  crystalline substance.
• Table salt is a crystalline solid.
• Table salt is a mineral called Halite.
• The chemical symbol of salt is NaCl.

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Some Chemical Compositions

• Halite will always be NaCl
• Quartz will always be SiO2

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Different Minerals

• Quartz
• Feldspar
• Potassium Feldspar
• Pyroxene
• Mica, Biotite Muscuvite
• Clay
• Calcite

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Physical Properties are used to identify mineral
and rock samples.

• Color
• Streak
• Luster
• Hardness
• Crystal Form

• Cleavage or Fracture
• Specific Gravity
• Striations
• Magnetic
• Chemical Test

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Color- Not the best indicator.

• The color may change due to the light.

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Streak- More reliable than color.

• The pulverized mineral hematite always leaves a
  red streak though it may be brown or black in
  color.

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Luster- The quality and intensity of light
reflected from the surface of the mineral.
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Mohrs Hardness Scale-
Scratch-ability

• 1. Talc
• 2. Gypsum-Fingernail
• 3. Calcite-Copper coin
• 4. Fluorite
• 5. Apatite-Knife blade, glass
• 6. Feldspar-File
• 7. Quartz
• 8. Topaz
• 9. Corundum
• 10. Diamond

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Crystal Form-

• Definite geometric relationship to one another.

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Cleavage-

• Cleavage is the ability to break along a
  preferred direction. For instance a diamond can
  be cut along a preferred edge to give its unique
  shape.
• Halite has 3 cleavages.
• Calcite has 3 cleavages.
• Biotite has 1 cleavage.

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Fracture-

• Sometimes a mineral will not have unique edges
  but will break or fracture or have irregular
  fracture points.

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Specific Gravity-

• Specific gravity is the density or heaviness of
  the mineral.

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Striations-

• Striations are parallel lines on a flat surface
  of the mineral.

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Magnetic

• The mineral Magnetite is easily identified
  because it is attracted to a magnet..

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Chemical Test

• Those minerals containing CO3-2 react with weak
  acids to produce CO2 gas.
• If a small amount of hydrochloric acid is dropped
  onto some minerals they will fizz.