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Minerals
Notes for Chapter 4
What is a mineral?
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A mineral is a substance that…
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Is naturally occurring
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Inorganic
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Not a liquid or a gas
Crystal Structure
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Not made from dead plant/animal matter
Solid
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Meaning NOT man-made
Particles are set in a specific and fixed pattern
Definite Chemical Composition
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Each element in the mineral has a specific proportion
Identifying Minerals
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Geologists know about 3800 minerals on
Earth.
To tell each one apart, they have written
down characteristics.
Currently – there are 7 basic characteristics
Identifying Minerals
7 Characteristics
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Streak
Luster
Density
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Hardness
Crystal Structure
Cleavage and Fracture
Color
Identifying Minerals
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Color
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This trait refers to how the mineral looks on the outside. But
– it can not be the only identifying mark as some minerals
can have the same color and not be the same mineral.
Can you tell which one is the “real” gold?
Identifying Minerals
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Streak
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Another clue into identifying a mineral is its streak.
The streak of a mineral is the color of its powder.
This is tested by taking the mineral and rubbing or
“streaking” it on an unglazed porcelain tile.
Identifying Minerals
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Luster
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This is the “BlingBling” category.
Luster is measured by how much light is reflected off the
object.
Identifying Minerals
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Density
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D= m/v
You remember this, right? This is how much stuff
you have divided by how much space you put it
in.
No matter what size sample you have, the
mineral will ALWAYS have the same density.
Identifying Minerals
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Hardness
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This is a “deal breaker” for
identifying minerals.
Austrian “Scientist Dude”
Friedrich Mohs created a
rating system for mineral
hardness.
Minerals are rated on how
they can be scratched.
See pages 118 and 119 in
textbook.
Moh’s Hardness Scale
Identifying Minerals
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Crystal Systems
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Geologists classify minerals according to 6 crystal forms
based on the number AND angle of the crystal faces.
Identifying Minerals
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Cleavage and Fracture
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How a mineral breaks is as important as how it is formed.
Cleavage breaks are clean without any jagged edges.
Fracture breaks are messy with irregular surfaces.
Exceptions to the Rules
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Of course – this is science!
Some minerals can have special properties…. Like
fluorescence or magnetism or reactivity…
How do minerals form?
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There are two basics
ways that minerals form
on Earth.
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Magma and Lava
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Solutions
Minerals from Magma and Lava
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Minerals form when the hot magma cools
inside the crust.
Minerals form from lava when it hardens on
the surface of the Earth.
When these liquids hardens – they form
crystals.
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Crystal size will depend on how fast the liquid
cools. The faster it cools – the bigger the crystal
size.
Minerals from Solutions
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A solution is when one substance is
dissolved into another.
Minerals can be created when their
components are dissolved in a liquid. The
liquid evaporates and the crystals of the
mineral are left behind.
Minerals can also form in a hot water solution
– where the water is hotter than the mineral
and the mineral cools.
Using Mineral Resources
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OK – Now you know
how to find minerals
and how to identify
them – now what?
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Figure out how you can
use them!!!!
Using Mineral Resources
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Gemstones and
Jewelry
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Metals
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Foods and Medicine
Review for Test
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List 5 characteristics of minerals
Define 7 properties of minerals
Describe 2 ways minerals are formed
Compare and contrast ways that minerals
are used in everyday life
Review for Test
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List 5 characteristics of minerals
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Naturally occurring
Inorganic
Solid
Crystal structure
Specific chemical composition
Review for Test
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Define 7 properties of minerals
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Color
Streak
Luster
Density
Hardness
Crystal Systems
Cleavage and Fracture
Review for Test
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Describe 2 ways minerals are formed
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Magma and Lava
Solutions
Compare and contrast ways that minerals
are used in everyday life
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Sounds like a great open – ended question!!!!
The End….
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KLM ENTERPRISES
2008