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Mineral Characteristics
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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 earth’s surface.
B.) Form from minerals dissolved in liquid.
- After the water evaporates the mineral stays
behind & dries. This forms the mineral.
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.
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 mineral’s atoms are arranged in a definite pattern, that
repeats over and over again.
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.
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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.
“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
mineral’s 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.
“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.
“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.
“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.
“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
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)
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 pressurewhen 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.
II. Types of Rocks:
A. Igneous Rock Origin:
1. Forms when magma or lava cools
into rock.
2. Magma- melted rock below the
earth’s 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.
5. When magma reaches the earth’s
surface it is called lava.
6. Lava then cools quickly and forms
igneous rock
7. Magma can also cool slowly under
earth’s surface and form igneous rock.
B. Classification of Igneous Rock:
1. Intrusive Rock- Type of igneous rock
that forms when magma cools under
earth’s surface.
a.) Large mineral crystals.
b.) Magma cools very slowly. This
gives the magma time to form
large mineral crystals.
c.) Coarse grain texture.
2. Extrusive Rock- Type of igneous
rock that forms from lava that cooled
above the earth’s 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.
“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 rock’s form will change.
4. The pressure of the overlying rock
squeezes the mineral grains together
forming new or larger mineral grains.
5. This changes the rock’s 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.
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.
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.
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.
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:
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.
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
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.
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.
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.