Transcript Minerals - Ms. Banjavcic`s Science

Chapter
3
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What is a mineral?
- naturally occurring, inorganic solid with a definite
composition and an orderly arrangement of atoms.
There are about 4000 different minerals on Earth.
All share five characteristics:
They are:
1) Formed by natural processes.
2) Inorganic: are not, and never were, alive
3) Crystalline: atoms are arranged in a pattern that is
repeated
4) Solid: definite volume and shape (gasses and liquids don’t
have a definite shape)
5) All elements or compounds with a definite chemical
composition.
Structure of Minerals: (pg. 64)
Structure of minerals are various forms of:
• Crystals: solid in which the atoms are arranged in a
repeated pattern
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Crystals from Magma:
› Magma – hot melted rock material that cools
when it reaches the Earth’s surface.
› As it cools, atoms lose heat energy, move closer
together and combine into compounds.
› These compounds arrange themselves into
orderly, repeating patterns.
› The size of the crystals that form depends on
how rapidly the magma cools.
 When magma cools slowly, crystals are large
enough to see with unaided eye.
 When magma cools rapidly, crystals will be small.
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Crystals from Solution:
› Minerals dissolved in water.
 When water evaporates, as in a dry climate,
ions that are left behind can come together to
form crystals.
› If too much of a substance is dissolved in
water, ions can come together and crystals
of that substance can begin to form in the
solution…no need for evaporation.
90 elements occur naturally in Earth’s crust. Approximately 98%
of the crust is made of only 8 of these elements.
• Of the thousands of known minerals, only a few dozen are
common, and these are mostly composed of the eight most
common elements in Earth’s crust
Silicates – are minerals that contain silicon (Si) and oxygen
(O) and usually one or more other elements.
Since silicon and oxygen are the two most abundant
elements in Earth’s crust, these two elements alone
combine to form the basic building blocks of most
minerals.
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Chart on Pg. 66
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Physical Properties:
Appearance: what does it look like? (can’t rely on
this alone)
Hardness: measure of how easily a mineral can be
scratched
– Mohs Scale of Hardness: (pg. 69)
– The scale lists the hardness of 10 minerals. Talc
is the softest, has a hardness value of 1.
Diamond is the hardest with a hardness value
of 10.
– If you have two minerals that look the same and you
want to determine what each is, you can use this
scale.
– If you can scratch one of the minerals with a nail, but
not a fingernail then you know that the hardness of
the mineral is somewhere between 3 and 4
– Luster: describes how light reflects from the
surface of the mineral
• Metallic or nonmetallic… shines like a metal or
not?
- Specific Gravity: the ratio of it’s weight compared
with the weight of an equal volume of
water…how heavy it is.
– Color: color of mineral
– Streak: color of the mineral when it is
powdered… when you rub it across a surface,
what kind of mark is left?
– Cleave: when broken, mineral breaks along a
smooth flat surface
– Fracture: when broken, mineral breaks off with
uneven rough surfaces
Magnetic?
 How light bends if shined through it?
 Hydrochloric acid makes it fizz?
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Uses of Minerals
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Gems: highly prized minerals (pg. 74)
– - Special varieties of particular minerals
– - They are brighter, clearer and more colorful than common
minerals
Diamonds:
- very hard gem
- Used as an abrasive and cutting tool
Rubies:
- used to produce a specific type of laser light
Quartz:
- used in electronics and as timepieces
Ore: a mineral or rock that contains a useful substance that can be
mined at a profit
- Iron is an ore that is used from producing frying pans to ships
Titanium: is a durable, lightweight, metallic element that comes from
minerals.
- used in golf clubs, racing bicycles, automotive body parts, aircraft,
eyeglass frames and tennis rackets
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Mineral
Properties
Hardness
Luster
Cleavage
and
Fracture
Streak
Specific
Gravity