What is a Mineral?

Naturally-formed solid substance with a
crystal structure
Pyromorphite
What do all minerals have in
common?
All:
1.
2.
3.
4.
5.
Are formed by natural processes.
Are NOT alive and NEVER were alive
Have a definite volume and shape
Are elements or compounds with a unique
chemical makeup
Are made up of particles that are arranged in
a pattern that is repeated over and over
(called a CRYSTAL)
What do all minerals have in
common?


They must occur
naturally within the
earth.
Cement, bricks, steel,
and glass are not
minerals because they
are man made.
What do all minerals have in
common?


Minerals must be
inorganic. This
means that they
cannot arise from
materials that were
once part of a living
thing.
Coal is not a mineral
because it comes
from the remains of
plants and animals
What do all minerals have in
common?


Minerals have a
definite volume and
shape.
The particles that
make up the sample
do not move apart.
What do all minerals have in
common?





Minerals have definite
chemical compositions.
A mineral always contains
certain elements in
definite proportions.
Most minerals are
compounds.
Compounds are two or
more elements combined.
Some minerals are just
elements Copper, Gold,
and Silver.
What do all minerals have in
common?


Minerals have crystal
structures. These are
particles in minerals that
line up in a pattern that
repeats over and over
again.
Sometimes a crystal
structure is obvious and
sometimes its only visible
under a microscope.
Watch “Crystals” by Brainpop…
1.What element are diamonds made from?
2. What do all crystals have in common?
Groups of Minerals

Minerals are grouped by the elements
they are made of.
Beryl (Emerald)
Calcite
Amethyst
Mineral Group
Characteristics
Contain
Silicates
oxygen & silica
The most
abundant group
of minerals
MICA
Examples
Quartz, mica
Quartz
Mineral Group
Characteristics
Make
Non-Silicates
Silver
up only
5% of the
Earth’s crust
Include some
of the most
important
minerals
Examples
iron, copper,
gold, silver,
diamonds,
rubies
Copper
Diamond
Gold
Ruby
Iron
Mineral Group
Carbonates
Characteristics
Carbon
Examples
&
Calcite (CaCO3)
oxygen and a
positive ion,
such as calcium
Calcite with Duftite inclusions
Mineral Group
Oxides
Characteristics
Metallic
ion
and oxygen
Examples
Hematite
(Fe2)O3
Mineral Group
Sulfides
Characteristics
Sulfur
and a
metallic ion
Examples
Galena (PbS)
Mineral Group
Sulfates
Barite on Calcite
BaSo4 / CaCO3
Characteristics
Metallic
Sulfur &
oxygen
ion,
Barite
BaSo4
Examples
Barite (BaSO4)
Mineral Group
Native
Elements
Characteristics
Single
elements
Examples
Gold (Au),
Diamond (C),
Silver (Ag)
How do minerals form?

1) Cooling of magma (hot, liquid rock and
minerals inside the earth (from the
mantle))



Fast Cooling = No Crystals (mineraloids)
Medium Cooling = small crystals
Slow Cooling = large crystals
How do minerals form?

2) Elements dissolved in liquids (usually
water)
Physical Properties of
Minerals






Mineral appearance
Hardness
Luster
Specific gravity
Streak
Cleavage and fracture
Physical Properties of Minerals
(can be used to identify the mineral)
Color
 Can be misleading
 Can vary with the type of impurities
Physical Properties of Minerals
(can be used to identify the mineral)
Hardness
 How easily a mineral scratches
materials
 Mohs Hardness Scale
Scale from 1 (softest) to 10 (hardest)
 Test by seeing if the mineral can scratch
different objects (like human fingernail, copper,
penny, glass, steel file)

Properties
of
Minerals
Mohs Hardness Scale
Mineral
Rating
Testing Method
Talc
1
Softest known mineral. It flakes easily
when scratched by a fingernail.
Gypsum
Calcite
2
A fingernail can easily scratch it.
3
A fingernail cannot scratch it, but a
copper penny can.
Fluorite
Apatite
Feldspar
4
A steel knife can easily scratch it.
5
A steel knife can scratch it.
6
Cannot be scratched by a steel knife, but
it can scratch window glass.
Quartz
Topaz
Corundum
Diamond
7
Can scratch steel and hard glass easily.
8
Can scratch quartz.
9
Can scratch topaz.
10
Hardest known mineral. Diamond can
scratch all other substances.
Find out more…

“Electronic” Hardness Test
http://www.childrensmuseum.org/geomy
steries/cube/b2.html
Physical Properties of Minerals
(can be used to identify the mineral)
Luster
 Surface reflection
 metallic = shiny like
metal
 non-metallic = dull,
non-shiny surface
Pyrite has a metallic luster
Calcite has a non-metallic luster
Specific Gravity or
Density



The specific gravity of a mineral is the
ratio of its mass compared with the
mass of an equal volume of water.
Gold has specific gravity of
19
It means gold is 19 times heavier
than water.
19 times heavier
Density
Physical Properties of Minerals
(can be used to identify the mineral)
Streak
 The color of the powdered
form of the mineral
 The color of the streak can be
different than the mineral
 Minerals must be softer than
the streak plate
Streak…can help identify quartz
http://www.childrensmuseum.org/geomysteries/cube/b3.html
Physical Properties of Minerals
(can be used to identify the mineral)
Cleavage & Fracture



The way the mineral breaks
Cleavage—minerals break
along smooth, flat surfaces
and every fragment has the
same general shape
Fracture—minerals that break
at random with rough or
jagged edges
Cleavage
 Cleavage


is the way that mineral breaks.
Minerals that break along smooth, flat
surfaces have cleavage.
Mica has cleavage
and Fracture!...


Mineral that breaks uneven, rough, or
jagged surfaces have fracture.
Quartz has fracture
quartz
Identify the minerals below for
cleavage and fracture
CLEAVAGE
FRACTURE
in
Physical Properties of Minerals
(can be used to identify the mineral)
Other Properties

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Specific gravity (*excellent clue to
mineral’s identity) http://www.childrensmuseum.org/geomysteries/cube/b4.html
Attraction to magnets
Bending of light
Reaction with hydrochloric acid
Smell & taste
An illustration
appearance:luster,color and streak
An illustration
cleavage and fracture
Watch Classifying Minerals Clip
Watch Brainpop—“Mineral Identification”
1. If a mineral can scratch your fingernail,
the mineral is _______________ than
your fingernail.
2. What is luster?