1. Chapter 3 Minerals
Section 1 Properties of Minerals

2. Where do we find minerals?
 Museums
 Jewelry
 Building Materials
(glass and steel are made
from minerals!)
 Graphite (in your pencil)
 Food (iron and sodium are
important minerals in our
diet!)
 Caves
 Rocks!

3. How do we get minerals?
 We have to extract minerals from within the
Earth’s crust by mining.
 “minare” – means to mine.

4. What is the definition of a Mineral?
To be considered a mineral
something must be…..
1. Naturally Occurring
2. Inorganic- it does not form from
the remains of living things.
3. Solid
4. Crystal Structure-
Atoms in a mineral line up in a
repeating pattern forming a
crystal. Crystals have flat sides
called faces and geometric
angles.
5. Definite Chemical Composition-
Minerals can be made of
elements or compounds.

5. More on Definite Chemical
Composition….
•Minerals can be pure elements or
compounds.
•Example: Sulfur (S) is a pure element
(made only of 1 type of atom) in the
crust. It is also a mineral.
•Example: Pyrite (FeS2) is a
combination of elements, so it is a
compound, but it is also a mineral.
•Pyrite is Fools Gold!

6. Birthstones

7.  There are over 3000
minerals!
 In fact, 90% of
Earth’s crust is
made of minerals.

8. Silicate Minerals
 Most of the minerals in the crust are called
Silicate minerals. (minerals containing Silicon, Si
and Oxygen, O)
 Mica (KAl2(AlSi3O10)(OH)2), Talc (H2Mg3(SiO3)4),
Quartz (SiO2)

9. Let’s learn to identify some
minerals…
Now that you know something about
physical properties and mineral
formation, let’s identify some minerals.

10. How to Identify Minerals
 There are eight
things you can look
for to identify
minerals.

11. How to Identify Minerals
1. Color
 Sometimes you can identify a mineral
by its color.
 Sometimes you cannot because it may
come in a variety of colors and there
are many minerals that have the same
color.

12. Example:
 The mineral quartz
is often thought of
as clear but it can
also be the
following colors:
amethyst (purple),
citrine (yellow-
brown), agate
(multicolored),
aventurine (green),
smokey quartz
(gray), rose quartz
(pink)

13. How to Identify Minerals
2. Streak
 The streak is the color of
the mineral’s powder.
 It may be different from
the color of the mineral.
 You test the streak of a
mineral every day. What
mineral is this?
 Graphite!

14. How to Identify Minerals
3. Luster- how much light is reflected from the
surface. How “shiny” a mineral is.
 Quartz has a glassy luster
 Galena has a metallic Luster

15. How to Identify Minerals
4. Crystal Form
 Sometimes crystals
are obvious, other
times they can only
be seen through a
microscope.

16.  The crystals of each mineral ‘grow’ atom by atom to
form that mineral’s particular crystal structure.
Geologists classify these structures into groups
based on the number and angle of the crystal faces.

17. 5. Hardness
 Moh’s Hardness Scale rates a
mineral’s hardness. “1” being
the softest and “10” being the
hardest.
 Some minerals are ‘harder’ than
others or can ‘scratch’ other
minerals.
 A Diamond is the hardest known
substance on the planet so it
can scratch any other mineral!

18. 6. Cleavage or Fracture
 This describes how a mineral breaks.
 If a mineral has cleavage, it usually has
smooth sides that resemble the original
shape of the mineral.
Example: Mica
 If it fractures, it is irregular and jagged or
rough.
Example: Quartz

19. 7. Density
 Density is a measurable
property of a mineral.
 It will also make a mineral
feel heavy or light.
To calculate density:
D=m
v

20. 8. Special Properties
 There are numerous special
properties which help
identify minerals.
 This mineral (Fluorite) glows
under a black light!
 Magnetite is naturally
magnetic.
 Magnetite or “Lodestone”
was used by Vikings more
than 1,000 years ago as
compasses
 Sulfur smells like rotten
eggs.
 Calcite fizzes when acid is

21. Section 2: Mineral
Formation
How do minerals form?

22. Lets Review… What Is a Mineral?
 A mineral is a naturally occurring,
inorganic solid that has a crystal structure
and a definite chemical composition.

23. Crystallization
 All minerals must form through crystallization.
 Crystallization is when atoms are arranged to
form a material with a crystal structure.

24. Minerals Crystallize in 2 Ways…
1. Cooling of certain materials :
a. When Magma/ Lava Cools
- magma is beneath the earth’s surface and lava is
above.
b. When a hot water solution containing dissolved
elements and compounds cools, the atoms begin to
arrange into crystals.
2. Evaporation of a Solution –
When a solution contains minerals that are dissolved, if
the water evaporates the minerals will crystallize and
‘come out of solution’.

25. Minerals Crystallize in 2
1. On the earth’s surfacePlaces…
a. through evaporation or cooling of
solutions containing dissolved minerals,
elements, or compounds (seawater).
b. when lava cools and hardens.

27. Examples:
 Table Salt (NaCl) formed as
ancient shallow salty seas
slowly evaporated.
 Gypsum is another mineral
that forms from evaporation of
seawater.
 It is used in drywall.

28. Petrified Wood
 Petrified Wood is wood that has been fossilized by
being turned into minerals.
 This occurs when the wood soaks in water containing
dissolved minerals over a long period of time. As the
water evaporates, the minerals will crystallize in every
space of the wood, or the water dissolves the original
wood and mineral crystallization completely replaces it.
 Eventually, the mineral forms a perfect copy of the
wood, including cell structure and fibers! The
replacement mineral is usually a variety of quartz.
Petrified wood may be colored by chemical impurities
such as iron and copper.
 There are entire forests that petrified! When trees
become uprooted, deposited in water, and covered by
mineral-rich mud or volcanic ash, petrified forests can
form. The age of petrified wood varies from place to
place, but generally speaking most samples are
hundreds of millions of years old!

30. Minerals Crystallize in 2
Places…
2. Beneath the Earth’s Surface/Underground
a. hot groundwater with dissolved minerals cools
b. when magma cools and hardens

31. Examples:
 Minerals can be extracted
from the veins in the rock.
 A vein forms when hot
ground water (heated by
magma) containing
dissolved minerals travels
through rocks, cools, and
the minerals crystallize.
 Gold and Silver can be
extracted from veins in
rocks.

32. Examples…
 A geode is a rounded
hollow rock lined with
mineral crystals
inside.
 A geode forms when
hot water containing
dissolved minerals
seeps into a crack or
hollow rock and cools.

33. Deep Underground=Slow Cooling =
Large Crystals
 Minerals that have large crystals
Minerals that have large crystals
do so because magma or a hot
water solution is cooling SLOWLY
deep below the earth’s surface.
 When temperatures are high,
cooling occurs slowly and the
crystals are large and it is easy to
see the flat, smooth sides and
geometric angles.
 Extreme Example: Selenite
(Gypsum) crystals that formed
from a hot water solution cooling
slowly in a deep cave in Mexico
below earth’s surface for 500,000
years!
http://www.youtube.com/watch?v=wgUFb_l4DLE

34. At or near Earth’s Surface=Fast
Cooling=Small Crystals
 Minerals that have small
or microscopic crystals
do so because hot water
solutions, magma, or
lava cool at or near the
earth’s surface
 When temperatures are
low, cooling occurs fast,
and crystals are fine,
sometimes too small to
see at all.
 Remember, Fast is Fine!

35. Size and Available Space
 Minerals that have
large, perfect crystals
have had a long time
to ‘grow’ through slow
cooling, but they also
have had a lot of
room (such as in a
cave) to ‘grow’ large
and perfect.

36. Section 3: Using Mineral
Uses of Minerals: Resources
 Gemstones and jewelry
 Metals-examples: Aluminum,
Copper, Iron, Silver
 Quartz is used in glass making
 Talc is ground up to make baby
powder and is a main ingredient in
eye shadow and powdered makeup.
 Diamonds, the hardest known
mineral, are used in drill bits and
saws.
 Fun fact: Small pieces of mica used
to be used as glitter! (now it is made
of pieces of plastic and foil.)

38. Producing Metals from Minerals
 To produce metal from a mineral, a rock
containing the mineral must be located
through prospecting and mined, or removed
from the ground. Then the rock must be
processed to extract the metal.
 A mineral that contains a metal that can be
mined and sold at a profit is called an ore.
 Iron ores: Magnetite (Fe3O4) and Hematite
(Fe2O3)

39. Producing Metals from Minerals
 A prospector is anyone
who searches for an ore
deposit.
 Geologists prospect for
ores by observing rocks
on the land surface and by
studying maps of rocks
beneath the surface.

40. Mining
3 types:
1. Strip Mining-soil
scraped away to
remove ore
Strip mine

41. Mining
2. Open Pit Mining-giant pit
dug to remove ore. Open Pit Copper Mine, Utah
3. Shaft Mines-network of
tunnels dug deep in the
ground to extract ore
from veins.
Shaft Mine

42.  Smelting is a process which Ore Processing-Smelting
removes the useful metal Example: Iron Ore
from an ore.
 In iron ore smelting, a blast
furnace is filled with iron ore,
coke (baked coal) and
limestone (CaCO3).
 Huge quantities of hot air
blast in at the bottom of the
furnace, causing the coke to
burn, forming CO2 gas and
liquid iron.
 The liquid iron collects at the
bottom of the blast furnace.
 Any impurities left in the ore
combine with the limestone to
make the waste product slag, Iron ores: Magnetite (Fe3O4) and
which settles above the iron. Hematite (Fe2O3)

43. Have you heard of the “Hot-
Metal” Bridge?
 Once the iron was in a hot metal car, the Hot Metal Bridge in
Pittsburgh moved the iron by rail from the Eliza furnaces along
the Mon River to Pittsburgh's South Side to produce finished
steel.

44.  Carrie Furnaces, which were part of Homestead
Steel Works, are near the Waterfront in Pittsburgh.
They were also the site of smelting to produce iron
which was used to make steel.

45. Alloys
 After smelting, sometimes other
materials are added to the metal to
make an alloy.
 An alloy is a mixture of 2 or more
elements and has the properties of a
metal.
 Steel is an alloy made of smelted iron
(further purified by the Bessemer
process) and some carbon. The
addition of carbon makes steel harder
and stronger than iron.
 Adding the metal Manganese to steel
produces even stronger steel.
 Adding Chromium and Nickel to steel
produces stainless steel.

47.  Edgar Thomson Steel Works is a steel mill in North
Braddock, Pennsylvania originally built by Andrew
Carnegie. You can see it from Kennywood!
 It has 2 blast furnaces still in operation used to smelt
iron ore and then produce finished steel.