Minerals
What is a mineral?
Mineral- a naturally occurring, inorganic, solid that has a specific crystal
structure and chemical composition.
1)Naturally
occurring & Inorganic- made by the earth of
non-living material.
Examples - quartz, sulfur, diamond, gold, silver
Non-examples - brick, glass, steel (man-made)
2)Crystal
Structure- the repeating pattern that the particles
within a mineral form.
3)Solid-
Molecules are tightly packed into a rigid structure.
4)Specific
Chemical Composition- the elements that make
the minerals have a definite chemical formula.
Naturally occurring
and inorganic
-To be considered a mineral it must
have been formed by natural
geologic processes, and never
been part of a living thing.
Gypsum
Calcite
-Laboratory created gems
(synthetic diamonds, rubies, etc.)
don’t count as minerals.
Mineral or not?
-Sugar?
-Coal?
-Salt?
Crystal Structure
• Crystal
– A solid in which the atoms are
arranged in a repeating pattern.
Why do you think minerals that look like
these are more rare?
Most times, crystals aren’t formed
in a open space and are mixed with
other substances.
SOLID
• Solids
have a definite shape and volume,
which gasses and liquids do not. Therefore,
no gasses or liquids can be considered a
mineral.
MINERAL
NOT
NOT
Specific Chemical Composition
• There
are about 4000 known minerals on Earth. Each one is a
unique substance with its own chemical formula.
A few are formed from a
single element.
Most minerals are made of
mixtures of elements.
How are these minerals created?
1) From Magma – Magma is less dense than the
surrounding solid rock, so it rises and cools in
the upper layers of Earth’s interior where it
hardens.
-The type and number elements in the magma
will determine which mineral is formed.
2) From Solution – Minerals are often dissolved
in water (for example, sea salt). When the liquid
becomes “overfilled” with the mineral, solid
minerals will begin to form in the water.
IDENTIFYING MINERALS
• Luster
– The way in which a mineral reflects light.
• Hardness
scratched.
– A mineral’s ability to resist being
• Break
– The shape a mineral takes when breaking
(based on crystal structure).
• Streak
– The powder left behind by a mineral when
scratched.
• Color
• Density
– Mass/Volume
LUSTER
•
•
Non-Metallic – Any mineral
lacking the metallic look is
considered non-metallic.
Metallic Luster – Not all minerals
with metallic luster are metals.
Minerals in this
category can be
divided into 3 subcategories:
GLASSY LUSTER
DULL LUSTER
WAXY/WET
LUSTER
HARDNESS - The measure of how easily a mineral can be scratched.
•
A mineral’s hardness is the most reliable and useful test for identifying
minerals.
•
Friedrich Mohs developed a scale by which an unknown mineral’s
hardness can be compared to 10 minerals of known hardness.
MOHS HARDNESS SCALE
Mineral Name Hardness
Hardness of common objects
Diamond
10
Corundum
9
Topaz
8
Quartz
7
Streak Plate = 7
Feldspar
6
Steel Nail = 6.5
Apatite
5
Glass = 5.5
Fluorite
4
Calcite
3
Copper = 3.5
Gypsum
2
Fingernail = 2.5
Talc
1
How is a diamond shaped?
A mineral that cannot be
scratched by your
fingernail but can be
scratched by glass, has a
hardness value
of_______?
2.5-5.5
A mineral that scratches
glass but gets scratched
by the steel nail has a
hardness value of
6
______?
BREAK – The shape a mineral takes when breaking.
Cleavage – a mineral that splits easily and evenly along flat
planes where atomic bonds are weak. (Having a pattern)
Fracture – Minerals that break with
rough or jagged edges because of
tightly bonded atoms. (random/no
pattern)
STREAK
HEMATITE
Sometimes, the same mineral will
look slightly different due to small
chemical impurities, but the streak
will look the same.
Do you think that mineral color
is always the same as the color
of the mineral’s streak?
Color
While mineral
color is one of the
less reliable clues
to a minerals
identity, it’s a
good starting off
point.
The presence of
trace elements
and compounds in
the mineral will
determine its
color.
Density- how heavy is the mineral?
Some minerals are heavier than
others, meaning
they are
more
Galenaextremely
dense. They have more molecules
heavy mineral
packed into a given volume,
making them weigh more.
Also used as the rare
mineral “unobtainium” in
the move Avatar.
Other Properties
Some minerals have other unique characteristics that determine their identity.
Smell - Sulfur smells like
rotten eggs
Magnetism - Magnetite is
magnetic
Taste - Halite tastes
salty
Fluorescence- glows under UV lights
Franklin County, NJ has the most Florescent mineral mined collection in the
world!!!!
The Economy of Minerals
Ore – A rock or mineral that contains a valuable
substance which can be mined for profit.
Iron
Ore
BEFORE
Gold
Ore
AFTER
The Economy of Minerals
Gem – Valuable minerals that are prized for their rarity and beauty.
Diamond
Topaz
Ruby
Emerald
Sapphire
MINERAL IDENTIFICATION PROCEDURE
After completing all tests, use your packet to identify
the specific mineral name.
1. LUSTER- Is the luster metallic, glassy, dull, or waxy/pearly/wet
looking?
2. BREAK – Does it display fracture (random pattern) or cleavage (specific
pattern)? If cleavage, specifically what type? (thin sheets, squared, cubic)
3. HARDNESS – What is the hardness? Finger nail, copper coin, glass,
steel nail, streak plate.
4. STREAK – Use the streak plate to determine the color of the mineral’s
powder
5. COLOR – Give the mineral a DETAILED COLOR DESCRIPTION.
6. OTHER PROPERTIES – Does the mineral have any unique
characteristics (smell, taste, magnetic, fluorescent, density, etc)?