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 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
1. Appearance - you cannot rely on a minerals
appearance alone to tell them apart. Ex. Gold and
Pyrite (Fools Gold).
2. 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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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?

3. 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.
4. Color - Can help in identifying minerals.
A.) Usually not enough.
B.) Gold and Pyrite.
5. 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 greenish brown streak.
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Mineral Identification Cont.
6. 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.
7. 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.
8. 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.
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The Rock Cycle
I. The Rock Cycle
A. What is a rock?
1. Rock- A mixture of one or more minerals,
rocks, non-minerals, or organic materials.
2. Example- Granite is made of feldspar,
quartz, mica, and hornblende.
B. How are rocks formed?
1. Rock Cycle- The process by which over many
years, this causes the changing of rocks from
one kind to another.
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2. Three types of rocks are
a.) Igneous
b.) Sedimentary
c.) Metamorphic
3. These three types of rocks go through the
cycle of one or more of the following
a.) Melting- Rocks are heated up and turned
into magma or lava.
b.) Lithification- The process of sediment
being cemented or compacted into rock.
(Sedimentary rock forms this way)
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c.) Cooling- The process of magma or lava
solidifying into solid rock. Igneous Rock Forms
this way
d.) Weathering Erosion- The process of
rocks breaking down into sediments and the
movement of these sediments over time.
e.) Effects of heat and pressure- when
igneous, metamorphic or sedimentary rock are
placed under heat and pressure a new rock
forms. (Metamorphic Rock forms this way
f.) See the rock cycle.
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II. Types of Rocks
A. Igneous Rock Origin
1. Forms when magma or lava cools into rock.
2. Magma- melted rock below the earths
surface.
3. Why does the magma or lava cool?
4. First, magma is less dense than any
surrounding rock layers, so it begins to rise
to the surface.
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5. When magma reaches the earths surface it
is called lava.
6. Lava then cools quickly and forms igneous
rock
7. Magma can also cool slowly under earths
surface and form igneous rock.
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B. Classification of Igneous Rock
1. Intrusive Rock- Type of igneous rock that
forms when magma cools under earths surface.
a.) Large mineral crystals.
b.) Magma cools very slowly. This gives the
magma time to form large mineral crystals.
c.) Coarse grain texture.
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2. Extrusive Rock- Type of igneous rock that
forms from lava that cooled above the earths
surface.
a.) Small mineral crystals.
b.) Lava cools very quickly. This does not
give the lava time to form large mineral
crystals.
c.) Fine grain texture.
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Metamorphic Rocks
I. Origin of Metamorphic Rock
A. Metamorphic Rock- The type of rock that
forms from existing rock that is changed by
heat, pressure, chemical reactions.
1. Underground rocks are under heat
pressure.
2. Eventually, if under enough heat the rock
will melt and form magma.
3. In areas where melting does not occur, the
rocks form will change.
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4. The pressure of the overlying rock
squeezes the mineral grains together forming
new or larger mineral grains.
5. This changes the rocks identity.
C. Examples
1. Granite can be squeezed into Gneiss.
2. Shale can be squeezed into Slate.
3. Basalt can be squeezed into Schist.
4. Slate can be turned into Phyllite, then
Schist, and eventually Gneiss.
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II. Classification of Metamorphic Rocks
A. Metamorphic Rocks are classified into two
groups.
1. Foliated Rocks- type of metamorphic rock
created when mineral grains flatten and line up
into parallel bands.
2. Non-Foliated Rocks- type of metamorphic rock
created when mineral grains change, grow and
rearrange, but do not form bands.
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B. Characteristics of Metamorphic Rocks
1. Foliated Rocks
a.) Bands of minerals are around the rock.
b.) Can be easily separated along these
bands.
2. Non- Foliated
a.) Bands of minerals are not present.
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III. Origin of Sedimentary Rock
A. Sediments- Are loose materials such as
rock fragments, minerals, and bits of organic
material, that have been moved by wind, water,
ice, and/or gravity.
B. Sedimentary Rock- Rock formed when
sediments are compacted or cemented together.
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C. Where does the sediment come from?
1. The process of weathering erosion.
2. Weathering- is the process that breaks
rocks into smaller pieces.
3. Erosion- is the movement of the weathered
material.
IV. Sedimentary Rock Formation
A. Sedimentary rock can form two ways
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1. Compaction- occurs when layers of small
sediment become compressed by the weight of the
layers above them.
2. Cementation- occurs when large sediments
are glued together by minerals deposited
between the sediments.
B. Examples of Compaction Cementation
1. Compaction
a.) Mud compacted with your hands.
b.) When it dries the mud forms a hard
substance.
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2. Cementation
a.) Water dissolves natural cement makers.
b.) Water then travels through the gaps in
the sediment and deposits the cement material.
c.) When dried, sediment sticks together.
V. Classification of Sedimentary Rock
A. Are usually classified into three groups.

1. Clastic 2. Chemical 3. Organic
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B. Clastic Rock
1. Clastic Rock- are made from the broken
parts of other rocks. These parts can be
compacted or cemented together.
2. Clastic rocks have two categories
a.) Conglomerate- rounded off sediment.
b.) Breccia- sharp edged sediment.
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C. Chemical Rock- form when minerals are
precipitated from a solution or are left behind
when a solution evaporates. This material is
then compacted or cemented together.
2. examples
a.) Limestone- Calcium Carbonate is in
solution in ocean water. When it comes out of
solution limestone is deposited.
b.) Rock Salt- Halite mixed with other
minerals. When lakes and seas evaporate they
often deposit rock salt.
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D. Organic Rock
1. Organic Rock- forms from the remains of
once living things.
2. Examples
a.) Chalk / Coquina- form from the shells of
living things that are compacted or cemented
together.
b.) Coal- Dead plant material compacted over
millions of years.