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Chapter 3
Minerals
Section 3-1 H.W. pg 66 ques.1-4
& pg 84 ques. 2,4,8,11,12,15
• Minerals are very important in everyday
life. Minerals, bricks, and glass are some
examples of how we use minerals.
• Mineral- is a naturally occurring, inorganic
solid with a definite chemical composition
and an orderly arrangement of atoms.
• There are about 4,000 minerals on Earth.
Mineral Characteristics
1) All minerals are formed by natural
processes. These processes occur on or
inside the Earth with no human
interaction.
Ex: Salt forms by the natural evaporation of
salt water. This type of salt comes from a
mineral called Halite.
Salt water solution made in a lab is not a
mineral.
Mineral Characteristics
2) Minerals are inorganic- this means that
there is no Carbon is present in minerals.
3) Every mineral is an element or compound
with a definite chemical composition.
4) All minerals are crystalline solids. And all
crystals have a definite volume and shape.
Crystals
• Crystal atoms are arranged in a pattern
that is repeated over and over again.
Ex: Graphite atoms are arranged in layers.
Opal- is not a mineral because it has no
repeated atom patterns.
Structure of Minerals
• All minerals are crystalline solids.
• Crystalline solids- are solids in which the
atoms are arranged in an orderly repeated
fashion.
• This does not mean that all minerals look like
crystals.
Ex: Rose quartz doesn’t look like a crystal
because it develops in tight spaces.
Clear quartz forms in open spaces and its
appearance is clearly crystal shaped.
Crystal vs. Non-Crystal
Crystal Formation
• Crystals form in two ways:
1) From cooling Magma
2) Could form in solution
Mineral formation from Magma
• Magma is hot melted rock material, that cools
when it reaches the Earth’s surface.
However in some cases it could cool before it
reaches the surface.
When magma cools its atoms lose heat and
energy. When this happens the atoms move
closer together and begin to form compounds.
During this cooling period is when atoms of
minerals begin to form repeating patterns.
Crystal Formation from Magma
The type of atoms present and the amount
will determine what mineral is produced.
• When magma cools slowly large crystals
form.
• When magma cools quickly then small
crystals form.
Crystal Formation from Solution
• Crystals form minerals dissolved in water.
• When water evaporates, ions are left
behind that can combine to form crystals
like halite. (salt)
• Or
• If there is too much substance in solution
the crystals could form in the solution
Silicates
• The most common rock forming minerals
belong to a group called the silicates.
• Silicates are minerals that contain the
elements O and Si (oxygen and silicon)
• These two elements combine the rocks of
the Earth’s crust and mantle.
• Ex: of Silicates are Quartz and Feldspar
Quartz and Feldspar Pics
How to Identify Minerals
Section 3-2 H.W. pg. 72 ques. 1-4
& pg. 84 ques. 1,3,5,7,10,13,14,16,17
• We identify minerals by some very specific
physical features and properties.
Color is one way to tell the difference between two
minerals but color alone is not enough.
Ex: Gold and pyrite both have the same color, but
they are two very different minerals. Pyrite has
very little value compared to gold.
So to tell these two apart you have to look at other
properties.
Gold and Pyrite
5 Major properties used to
distinguish between minerals
1)
2)
3)
4)
5)
Hardness
Luster
Specific gravity
Streak
Cleavage/ fracture
5 major properties
1) Hardness- This is
the measure of how
easily a mineral can
be scratched.
Ex: Talc, a very soft
mineral can be
scratched with just
your finger nail.
Hardness of Minerals
• Diamonds, on the
other hand are the
hardest mineral.
• The only this that can
scratch a diamond is
another diamond.
• Remember scratch
and break are not the
same. If hit hard
enough a diamond
will shatter.
Mohs Scale
• In 1812 the Mohs scale of mineral hardness was devised by the
German mineralogist Frederich Mohs (1773-1839), who
selected the ten minerals because they were common or
readily available. The scale is not a linear scale, but somewhat
arbitrary.
Hardness of some other items:
• 2.5 Fingernail
• 2.5–3 Gold, Silver
• 3 Copper penny
• 4-4.5 Platinum
• 4-5 Iron
• 5.5 Knife blade
• 6-7 Glass
• 6.5 Iron pyrite
• 7+ Hardened steel file
5 major properties
2) Luster- This is the way a mineral reflects
light.
This reflection could be metallic, meaning it
shines like a metal, or non-metallic or dull
or glassy looking.
Luster
5 major properties
3) Specific Gravity- This is the ratio of the
minerals weight compared to the weight of
an equal volume of water.
Ex: Specific Gravity of Gold is 19:1 or 19.
This means that gold is 19x heavier that
water.
How could you find out the volume of a
solid?
5 major properties
4) Streak- Is the color of a mineral when it is in
powder form.
So if we have a solid mineral we would streak it
across a piece of porcelain to see what color is
left behind.
5 major properties
5) Cleavage/ Fracture- this is the way a mineral
breaks.
Minerals that break along a smooth flat surface
have cleavage.
5 major properties
• Cleavage/ Fracture- Minerals that break
unevenly, or with rough jagged surfaces have
fracture.
Other unique properties
• Magnetite- is attracted to metal like a
magnet.
Other unique properties
• Calcite- When light passes through this mineral 2 rays
form and it allows you to see a double image.
• Also when you add HCl to it fizzes.
Uses of Minerals
Section 3-3 H.W. pg 84 ques. 6,9 & pg. 86 ques. 6,7-10
• Gems- Gems are highly
prized minerals due to
their rareness and
beauty.
• They are clearer brighter
and more colorful then
common minerals.
• Gems always come from
other minerals.
• Ex: Amethyst is a gem
that comes from Quartz.
Because it has less iron
in it than quartz does it
has a beautiful purple
color.
Some important gems Taken from
Minerals are:
• Emeralds from Beryl
• Ruby from Spinel
• Blue Sapphire from Corundum
More are on the chart on pg. 75
Some gems are more prized than others.
Cullinan Diamond- The largest diamond ever
found. (3,106 karats)
Hope Diamond- Owned by Henry Philip Hope.
(45.5 karats)
Useful Gems
• Some gems are very useful like diamonds.
• They are not only used to make beautiful
jewelry but since they are the hardest
mineral on Earth they are also used for
cutting tools like saw blades.
• Rubies are used to create lasers.
• Quartz is used in watches and clocks.
Useful elements that are found in
minerals
•
Gems are the most popular use of minerals but
they are not the most important. We use
minerals for other very important uses.
1) Ores- An ore is a mineral or rock that contains
a useful substance that can be mined.
Iron ore is used in almost everything from
frying pans to ships and it comes from the
mining of the minerals Hematite & Magnetite.
Useful elements that are found in
minerals
• Aluminum- is mined from Bauxite as
aluminum oxide powder.
We make the powder in things like aluminum
sheets by a process called smelting or
melting at very high temps.
We use aluminum in soda cans, siding for
homes, air planes, baseball bats.
Useful elements that are found in
minerals
2) Vein Mineralsmineral deposits left
behind that fill the
open spaces of rocks.
Under certain conditions
minerals dissolve in
solution. This
mineral/water mixture
will travel through
weak cracks in rocks
and be deposited in
these spaces.
Vein Minerals
• Sometimes vein mineral deposits fill in
empty spaces after rocks collapse.
Ex: Sphalerite, which comes from zinc and
is used in batteries.
Useful elements that are found in
minerals
3) Minerals that contain Titanium- Titanium
is a durable, light weight, metallic element
that derived from rutile and ilmenite.
We use titanium in car bodies planes,
eyeglass frames, tennis rackets, bikes and
wheel chairs.
Test on Chapter 3 in one
week!!!!!!