Mineral Characteristics

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Mineral Characteristics

• I. Mineral Characteristics

A. Mineral - is a naturally occurring, inorganic
solid with a definite structure and composition.
B. There are more than 4000 minerals found on
earth.
C. All minerals share five characteristics.
1. All minerals are formed by one of three
natural processes.
A.) Formed from cooled magma.
- Magma - hot melted rock under earths surface.
B.) Form from minerals dissolved in liquid.
- After the water evaporates the mineral stays
behind dries. This forms the mineral.
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C.) New minerals could form from existing
minerals.

• They could be transformed by
• Heat
• Pressure
• Chemical Reaction

• Mineral atoms change without melting, allowing
  the atoms to recombine in new ways.

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Mineral Characteristics Cont.
2. All minerals are inorganic.
A.) Minerals are not alive, never were, and were
not made up by once living things.
B.) Example Is coal a mineral? Is Oil a
mineral? Coal and Oil formed from one living
things.
3. All minerals are solid and have a definite
shape.
A.) Liquids Gases could never be minerals
because they do not have a definite shape.
4. All minerals have definite chemical
compositions.
A.) Some rocks are made of different things.
5. A minerals atoms are arranged in a definite
pattern, that repeats over and over again.
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Mineral Characteristics Cont.
A.) The repeating pattern of atoms are called
crystals.
B.) When magma cools slowly, large crystals form.

C.) When magma cools rapidly, small crystals
form.

• II. Mineral Identification

A. Properties of minerals
Appearance - you cannot rely on a minerals
appearance alone to tell them apart. Ex. Gold and
Pyrite (Fools Gold).
1. Hardness - is how easily a mineral can be
scratched.
A.) We can use hardness to identify minerals by
using the Mohs Scale of Hardness.
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Questions

• About how many minerals are found on earth?
• What are the five characteristics that all
  minerals must have?
• What are the three ways a mineral can form
  naturally?
• Why is coal not a mineral?
• Can liquids or gases ever be minerals? Why?

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Mineral Identification Cont.
B.) An object with a hardness of 1 is the
softest, and an object with a hardness of 10 is
the hardest mineral.
C.) Objects with the same hardness will scratch
each other.
D.) Which mineral is harder Quartz or Calcite?

2. Luster - Describes how light is reflected from
the minerals surface.
A.) Luster will be either metallic or
nonmetallic.
B.) Metallic - shines like metal.
C.) Nonmetallic - does not shine like a metal.

D.) Ex. Gold - metallic, Quartz - nonmetallic.

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Mineral Identification Cont.
3. Color The appearance of the mineral in
reflected light. What you see to the naked eye.
A.) Usually not enough.
B.) Gold and Pyrite.
4. Streak - is the color of the mineral when it
is broken up and powdered.
A.) When a mineral is rubbed across an object
with a greater hardness a streak of color is
sometimes left behind.
B.) Ex. Gold leaves a yellow streak, and Pyrite
leaves a grayish streak.
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Mineral Identification Cont.
5. Cleavage - Minerals have cleavage if it can
break across a smooth flat surface.
A.) Ex. A layer cake taken apart in layers is
broken with perfect cleavage.
B.) Halite and Calcite break with perfect
cleavage.
6. Fracture - Minerals that break with rough or
jagged edges have fracture.
A.) Grabbing a chunk out of a layer cake would be
like breaking a mineral with fracture.
B.) Quartz has fracture.
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Mineral Identification Cont.
7. Special Properties - some mineral have unique
properties.
Examples
A.) Calcite fizzes when Hydrochloric Acid (HCl)
is put on it.
B.) Magnetite is attracted to magnets.
C.) Halite dissolves in water.

• III. Uses of Minerals

A. Gems - a valuable mineral highly prized
because they are rare and beautiful.
1. Most minerals are forms of gems.
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Uses of Minerals
2. Example Amethyst is a gem form of Quartz.

3. The gems value depends on its rarity, size
and cut.
4. The most rare and valuable gems are called
Precious Stones.
5. All other gems are called Semiprecious Stones.

A.) Examples Amethyst, Turquoise, and Topaz.

B.) Ores - a mineral that contains a useful
substance that can be extracted and used for a
profit.
1. Iron can be extracted from Hematite.
2. Aluminum can be extracted from Bauxite.

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Uses of Minerals
3. The value of an ore depends on its supply
its demand and cost of extraction.
4. If it cost raises, or demands fall, a
substance may not be considered an ore.

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Removing Iron from an ore

• Iron ores are typically the iron atom bonded with
  oxygen.
• The metallic iron can be removed from a process
  called smelting
• Iron ore is crushed and mixed with limestone and
  coke (baked coal)
• Mixture is placed in a blast furnace with
  extremely hot air to make the coke easily burn.
• Chemical reactions with the coke changes allow
  the mixture to form carbon dioxide gas and molten
  iron
• Molten iron sinks to the bottom of the furnace as
  impurities combine with the limestone to make
  slag (floating on top).
• Slag is removed and iron is poured out through
  taps.

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Processing of iron

• 98 of iron is used in the production of steel.
• Steel is an alloy made from mostly iron and
  carbon.
• Alloy is a mixture of two or more elements with
  at least one being a metal.

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Questions

• 6). Can you rely on a minerals appearance or
  color alone, in identifying a mineral? Why?
• 7). How do you use the Mohs hardness scale?
• 8). If you rub two minerals together and both of
  them are scratched, what can be said about those
  two minerals?
• 9). What is the difference between metallic and
  nonmetallic?
• 10). What determines a gemstones value?
• 11). What determines the value of an ore?