Download Minerals

What is a Mineral?
In Geology…
A mineral is a naturally occurring, inorganic solid
that has a crystal structure and a definite
chemical composition.
Some examples…
Naturally Occurring…
Seen in nature. Not man made.
Inorganic…
• Cannot form from material that was once living
• Organic = life!
Crystal Structure…
Mineral particles line up in a pattern that repeats
itself over and over again.
Definite Chemical
Composition
Definite = always the same
Minerals always contain the same elements in
the same ratios.
SiO2
KAlSi3O8
Solid…
Definite volume and shape
How do Minerals form?
Crystallization of melted material (aka magma/lava)
Minerals form as magma cools
Crystallization of materials dissolved in water
When hot water cools or evaporates, minerals
crystallize
Where do we find
Minerals?
Most of Earth’s crust is made up of common
minerals (like quartz)
Less common minerals are not evenly
distributed around the planet
Many valuable minerals are found in or near
areas of volcanic activity or mountain building.
Where can you find diamonds?
Where can you find oil?
Why do we care?
All rocks are made of at least one mineral!
How can we differentiate minerals and rocks??
Many minerals are important to our daily lives
Gemstone
Metals (Silver, copper)
In foods, medicines, fertilizers, building materials
 Is it formed in nature?
 Is it non-living material?
 Does it have a chemical composition?
 Does it have a crystalline structure?
 Is it solid?
Wood
Gold
Fossil
Topaz
Bones
Granite
Quartz
Pearls
Talc
Icebergs
Diamond
Coal
Glass
 Minerals
2 - Gold
4 - Topaz
6 - Quartz
9 - Talc
10 - Iceberg*
11 - Diamonds
 Non-Minerals
1 - Wood - once living
3 - Fossils – once living
5 - Bone - living material
7 - Granite - intrusive igneous rock
8 - Pearls – made by oysters
12 - Coal - Sedimentary rock
13 - Glass-Human made
* According to IMA – ice is listed as a mineral
1. Naturally occurring
2. Inorganic
3. Solid
4. Crystal structure (due
to internal arrangement
of atoms)
5. Definite chemical
composition
MINERALS
General Facts about Minerals
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Over 5,000 have been identified
A few are “native elements” -- made of only
one element, such as sulfur, gold. copper, and
graphite (carbon)
Most are compounds, especially the silicate
group (Si, O). Earth’s crust is 90% silicate
rocks!
Other important groups are oxides,
carbonates, and sulfides.
Less than a dozen are common in
most rocks
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Quartz
Feldspar (group)
Muscovite (white
mica)
Biotite (black mica)
Calcite
Pyroxene
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Olivine
Amphibole (group)
Magnetite, limonite,
and other iron
oxides
Pyrite
We will identify many of these in
our LAB activity : )
Silicates
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Silicon and oxygen are two of the most abundant
elements on earth
Silicates are the most plentiful minerals on earth
They are built around covalent bonds (Chemistry!)
of silicon and oxygen
Symbols
Silicon = Si
Oxygen = O
Silicates can build in a variety of
ways
O
O
O
O
Si O
O
Si
Si O
O
Si
O
O
O
O
Si O
O
O
Si
O
In flat sheets like mica
O
Or in crystals
0
0
Si
02
0 Si
0 00
Si
Si
0
Si
0 0 0
0
Si
0
0 0
Si
0
Or in crystals like quartz
Minerals are identified by their key
characteristics
Hardness
 Crystal structure
 Luster
 Color
 Streak
 Cleavage/fracture
 Density
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Special Properties
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reaction to acid
fluorescence
salty taste
magnetism
odor
Mineral Hardness
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Ability to scratch
another mineral
Mohs Hardness Scale
from 1 (talc) to 10
(diamond)
Quartz (most common
mineral) is 7
Color
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results from ability to
absorb some
wavelengths and
reflect others
some minerals have
characteristics
colors
Streak
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Color of the powder
when rubbed on a
“streak plate”
(unglazed porcelain)
May be same as handspecimen or different
Some paint is based on
powdered minerals
(streaks).
Luster
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Describes how light
reflects off the surface
Main categories are
“metallic” and “nonmetallic”
Non-metallic includes
“dull,” glassy,” waxy,”
“pearly”
Density (Specific Gravity)
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All minerals have density
(mass / volume), but
some are very dense
Examples include galena,
magnetite, and gold
Specific Gravity is the
density of the mineral
compared with density of
water
Crystal Shape (Form)
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External structure due to
internal arrangement of
the atoms
Six basic groups of
shapes, with about three
dozen variations
Mineral
cleavage/fracture
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A mineral that splits easily
along flat surfaces when
struck hard--this is called
mineral cleavage
Fracture- Describes how a
mineral looks when it breaks
apart in an irregular way.
A few minerals have both
cleavage and fracture
Special Characteristics
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Many minerals have some special characteristic that
helps us identify that mineral.
Special Characteristics-Fluorescence
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Fluorescent Minerals
Some minerals will
glow when placed
under short-wave or
long-wave ultraviolet
rays
Franklin and
Ogdensburg NJ are
famous for their
fluorescent minerals
Special Characteristic-Salty Taste
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DO NOT TASTE the
MINERALS!
Halite -it will taste
salty, just take my
word for it.
Special Characteristics-Magnetism
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Many iron minerals
will produce an
invisible magnetic
force field
“Lodestone” was
used by Vikings
more than 1,000
years ago as
compasses
http://www.minerals.net/mineral/oxides/magnetit/magneti4.htm
Special Propertiesreacts to acid
Calcite will bubble
up when acid is
poured on it.
Common uses include:
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Aluminum--packaging, transport, building
Beryllium--gemstones, fluorescent lights
Copper--electric cables, wires, switches
Feldspar--glass and ceramics
Iron--buildings, automobiles, magnets
Calcite--toothpaste, construction