Properties of minerals

Properties of Minerals

What is a
mineral?


The Rules of the Mineral
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Every Mineral must
follow these set of rules
1. Naturally Occurring
2. Inorganic
3. Solid
4. Crystal Structure
5. Definite Chemical
Composition


Mineral Questions
1. Are pearls considered minerals?
• No, because they are made from
animals.
2. Is naturally occurring glass considered
to be a mineral?
• No, because it does not have a crystal

structure.



Crystal Structure
A

crystal is a solid in which the atoms
are arranged in a pattern that repeats
again and again.
 Internal Arrangement of the Atoms
A tetrahedral site lies in the center of a 4-

A tetrahedral site lies in the center of a

4-


Definite Chemical
Composition

 This

means that a mineral always
contains certain elements in definite
proportions
 Quartz- always has one atom of Silica
for every two atoms of oxygen

The Mineral Beryl
Emerald
Aquamarine


The Mineral Corundum
 Ruby

Sapphire


Birthstones
January - Garnet July - Ruby
February - Amethyst August - Peridot
March -AquamarineSeptemberSapphire
April – Diamond
October - Opal
May – Emerald
November - Topaz
June - Pearl
December - Zircon


Identifying Minerals
Each Mineral has its own specific
properties that can be used to identify it.
1. Hardness
 2. Color
 3. Streak
 4. Luster

 5. Density
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6. Crystal Shape
 7. Cleavage &
Fracture
 8. Special
Properties
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Mohs Hardness Scale
1

= Softest (talc or graphite)
 10 = Hardest (diamond)
 How do you determine if one mineral is
harder than the other?
 Perform a scratch test.
 If the mineral gets scratched it is softer
than the object that scratched it.


Which mineral is gold?
How would you be able to

tell the difference?


Streak- the color of a mineral
when it is made into a powder


Pyrite(fool’s gold) is
very similar in color to
real gold, but Pyrite
has a greenish-black
streak and gold has a
gold streak.



Luster- describes how light
reflects off a minerals surface
 Metallic

Luster- describes minerals that
are shiny.
 Glassy Luster- describes minerals that
look like they have a glassy surface, ex.
Quartz
 *Minerals are usually described as
having a metallic or non-metallic luster.


Which mineral has a metallic

luster and which has a glassy
luster?


Crystal Shape
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Every crystal has a characteristic shape that is due
to its Crystal structure.
Halite(NaCl or Salt)- will always have six sides
and form a cube

Hoppered pink Halite crystals from the evaporation



Minerals will either break by
cleavage or fracture?
 Cleavage-

a minerals ability to split
easily along flat surfaces

 Fracture-

minerals which break with
rough or uneven surfaces

Special Properties
 Fluorescence-

some minerals glow under
ultraviolet light ex.) Fluorite
 Magnetism- some metallic minerals are
naturally magnetic ex.) Magnetite
 Effervescence- some minerals such as
Calcite fizz when acid is placed on it
 Electrical Properties- a few minerals,
such as quartz produce an electrical current


Fluorite


Scheelite(fluorescent mineral)