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Minerals
Chapter 2
Earth’s Surface
Characteristics of Minerals 2.1
Minerals and rocks are
different.
 Rocks
only have 2 characteristics of
minerals: solid and form naturally.
 Minerals must have all 4 characteristics of
a mineral.
 Rocks usually are made of two or more
minerals.
 Two rocks of the same type can have
different amounts of minerals.
Look at page 44
 Look
at the rock on page 44.
 It contains 3 different minerals.
Minerals have four
Characteristics
 Mineral




– a substance that
Forms in nature
Is a solid
Has a definite chemical make up
Has a crystal structure
Formed in Nature
 Minerals
are formed by natural processes.
 Most minerals are formed when water
evaporates (halite/salt), when lava cools
or from high pressure inside the earth that
changes rocks.
Solid
A
mineral is a solid.
 It has a definite volume and rigid shape.
 Liquid and gasses are not minerals.
 Water
is not a mineral, but ice is.
Definite Chemical Makeup
 Minerals
are always made up of the same
materials in the same proportions.
 Made up of a specific combination of
elements.
 Element – a substance that contains only
one type of atom
Crystal Structure
 Crystal
– a solid in which the atoms are
arranged in an orderly, repeating and
three-dimensional pattern.
 Each mineral has its own type of crystal
structure.
 Some minerals have the same chemical
make up, but different structures.
 Example: diamond and graphite
Brain Pop
 https://www.brainpop.com/science/eart
hsystem/crystals/
Diamond and Graphite
 Diamond
and
graphite are both
made up of the
element carbon.
 The carbon
elements are
arranged in
different ways
creating different
elements.
Grouping Minerals
 Minerals
are grouped or classified by their
chemical make up.
 Most common group is silicates.
 Silicates contain oxygen and silicon.

Quartz, Feldspar and Mica
Identifying Minerals
 Minerals




2.2
are identified by their properties.
Appearance
How it breaks
Density and hardness
Special properties
Appearance
 Color



and Streak
Color of minerals can change depending
on where it is.
Streak – the color of powder left behind
when a mineral is scraped across a surface.
Streak is a better clue to a mineral’s identity
than the surface color.
Appearance
 Luster
– the way light reflects from a
mineral’s surface


Metallic – looks like it is made of metal
Nonmetallic – can be shiny, but does not
appear to be made of metal
 Luster
can change after exposure to
weather. If a mineral is broken to reveal a
fresh surface the true luster can be seen.
How it breaks
 Cleavage
– the tendency of a mineral to
break along a flat surface.
How it breaks
 Fracture
– the tendency of a mineral to
break into irregular pieces.
 The mineral does not break along flat
surfaces because there are no particular
directions of weakness.
Density and Hardness
 Density
– amount of mass in a given
volume, mass per unit volume
A
mineral’s density is determined by the
kind of atoms and how closely they are
joined together.
 Look
on page 54
 What is more dense the tennis ball or
baseball?
 Estimate the size of a piece of quartz that
would be needed to balance the zincite
sample.
Density and Hardness
 Hardness
– resistance of a mineral to
being scratched
 Hardness is determined by crystal
structure harder minerals have stronger
bonds.
 Mohs
Scale
Mohs Scale
 Based
on fact that
a harder mineral
will scratch a softer
one.
 Talc is softest
 Diamond is hardest
Special properties
 React

with acid
Carbonate minerals will bubble when weak
hydrochloric acid is put on them.
 Fluorescence

Some minerals will glow under ultraviolet
light. Fluorite is one of these minerals
Special properties
 Magnetism

Some minerals are attracted to magnets.
Magnetitie is one of these minerals.
 Radioactivity

Some minerals contain unstable elements
that change over time.
Minerals are valuable
resources
 Minerals
are used in industry and art.
 How minerals form.
 Minerals are mined
2.3
Industry and Art
Technology
 Gemstones
are used in
jewelry
 Birthstone,
wedding rings
 Stones are
ground and
polished
before being
made into
jewelry.
Industry
Copper
Arts
How minerals form
1.
Water evaporates

2.
Substances that are dissolved in water are
left behind after evaporation
Hot water cools

Dissolved minerals separate from the water
as the water cools
How minerals form
3.
Molten rock cools



Magma – molten rock inside the earth
Lava – molten rock at Earth’s surface
Minerals form when the magma cools and
atoms join together.
How minerals form
4.
Heat and pressure

5.
Heat and pressure inside the earth cause
minerals to form as bonds are broken and
join again
Organisms produce some minerals

A few minerals are produced by living
organisms. Ocean animals produce calcite
in their shells.
Look on page 63
Minerals are mined
 Ores
– rocks that contain enough of a
mineral to be mined for profit
 Surface



Mining
Panning
Strip mining – stripping away the plants soil
and rocks to get to ore near the surface
Open-pit mining – Roads are built into the
large hole so trucks can haul the ore out.
Strip mining
Open-pit mining
Minerals are mined
 Deep



mining
Used when minerals are located deep
below the surface.
Tunnels are blasted, drilled, cut or dug to
get to the ore.
Deep mining is more expensive.
Deep mining