Minerals
Table of Contents
Properties of Minerals
How Minerals Form
Using Mineral Resources
Minerals - Properties of Minerals
What Is a Mineral?
•
Mineral – naturally occurring, inorganic
solid that has a crystal structure and a
definite chemical composition.
• A substance must have 5
characteristics in order to be
considered a mineral:
1. Naturally occurring – substance
cannot be man made
2. Inorganic - the substance cannot
form from materials that were once
part of a living thing
Minerals
What Is a Mineral?
3. Solid – substance must be a
solid with a definite volume and
shape
4. Crystal - a solid in which the
atoms are arranged in a pattern
that repeats again and again
5. Definite Chemical Composition
– the substance always contains
certain elements in definite
proportions
Minerals
Minerals
Identifying Minerals
• Geologists have identified
about 3,800 minerals. Each
mineral has characteristic
properties that can be used to
identify it.
• Color – can be used to
identify only those few
minerals that always have
their own characteristic color
– Ex: Malachite is always
green; Azurite is always blue
Minerals
Identifying Minerals
• Streak – the color of a mineral’s powder.
– Observe a streak by rubbing a mineral against
a piece of unglazed porcelain tile
– Streak color and mineral color are often
different.
Minerals
Identifying Minerals
• Luster – the way a mineral reflects light from
its surface.
– There are many different terms used to describe
various lusters. They include: metallic, glassy,
earthy, waxy, brilliant, and pearly
Minerals
Identifying Minerals
• Density – mass in a
given space or volume
– No matter what the
size of a mineral
sample, the density
of that mineral
always remains the
same.
Minerals - Properties of Minerals
Calculating Density
• To calculate the density of a mineral,
divide the mass of the mineral sample by
its volume.
Density = Mass/Volume
• For example, if a sample of olivine has a
mass of 237 g and a volume of 72 cm3,
then the density is
237 g/72 cm3 = 3.3 g/cm3
Minerals - Properties of Minerals
Calculating Density
• Practice Problem
• A sample of calcite has a mass of 324 g
and a volume of 120 cm3. What is its
density?
• 324 g ÷ 120 cm3 = 2.7 g/cm3
Minerals
Identifying Minerals
• Hardness – refers to the mineral’s ability
to resist scratching.
– Mohs hardness scale – ranks ten
minerals from softest to hardest
Minerals
Talc
Gypsum
Calcite
Fluorite
Apatite
Feldspar
Quartz
Topaz
Corundum
Diamond
1
2
3
4
5
6
7
8
9
10
Easily scratched by fingernail
Can be scratched by fingernail
Can be scratched by copper penny
Easily scratched with steel file/glass
Easily scratched with steel file/glass
Scratches glass with difficulty
Easily scratches both glass and steel
Scratches quartz
No simple tests
Scratches everything
Minerals
Identifying Minerals
• Crystal systems - crystals of each
mineral grow atom by atom to form
that mineral’s crystal structure.
– Classified into six groups based
on the number and angle of the
crystal faces
• Cleavage – mineral’s ability to split
easily along flat surfaces.
– Fracture – the way a mineral
looks when it breaks apart in an
irregular way.
Minerals
Identifying Minerals
• Special properties some minerals can be
identified by special
physical properties
– Ex: magnetism
(Magnetite), fluorescence
(Sheelite), radioactivity,
reaction to acids, optical
and electrical properties
Minerals - Properties of Minerals
Identifying Minerals
Minerals - Properties of Minerals
Mineral Density
• Use the line graph of
the mass and
volume of pyrite
samples to answer
the questions.
Minerals - Properties of Minerals
Mineral Density
• Reading Graphs:
• What is the mass of
Sample B? What is
the volume of Sample
B?
50 g; 10 cm3
Minerals - Properties of Minerals
Mineral Density
• Calculating:
• What is the density of
Sample B?
5 g/cm3
Minerals - Properties of Minerals
Mineral Density
• Reading Graphs:
• What is the mass of
Sample C? What is
the volume of Sample
C?
100 g; 20 cm3
Minerals - Properties of Minerals
Mineral Density
• Calculating:
• What is the density of
Sample C?
5 g/cm3
Minerals - Properties of Minerals
Mineral Density
• Comparing and
Contrasting:
• Compare the density
of Sample B to that of
Sample C.
The density of
samples B and C is
the same.
Minerals - Properties of Minerals
Mineral Density
• Predicting:
• A piece of pyrite has
a volume of 40 cm3.
What is its mass?
8g
Minerals - Properties of Minerals
Mineral Density
• Drawing
Conclusions:
• Does the density of a
mineral depend on the
size of the mineral
sample? Explain.
No; Larger samples
have more mass, but
the ratio between mass
and volume is constant.
Minerals - Properties of Minerals
Crystal Systems Activity
• Click the Active Art button to open a
browser window and access Active Art
about crystal systems.
Minerals - Properties of Minerals
Data Sharing Lab
• Click the PHSchool.com button for an
activity about sharing data for the Skills
Lab Finding the Density of Minerals.
Minerals - How Minerals Form
Where Minerals Form
• Minerals form on surfaces through evaporation
of solutions containing dissolved minerals.
• Minerals form beneath surfaces when dissolved
elements and compounds leave a hot water
solution or when magma cools and hardens.
Minerals - How Minerals Form
Where Minerals Form
• Geode – a hollow
rock inside which
mineral crystals have
grown.
• Crystallization –
process by which
atoms are arranged to
form a material with a
crystal structure.
Minerals - How Minerals Form
Minerals From Solutions
• Solution – a mixture in which
one substance is dissolved in
another.
– When elements and
compounds that are dissolved
in water leave a solution,
crystallization occurs.
• Some minerals form when
solutions evaporate
– Ex: salt crystals (Halite),
Gypsum, Calcite
Minerals - How Minerals Form
Minerals From Solutions
• Other mineral crystals form
from hot water solutions that
begin to cool.
– Many times the hot water
is a result of geothermal
(underground) heat
– Ex: Silver
Pure metals that crystallize from hot water solutions
underground often form veins
Vein – a narrow channel or slab of a mineral
that is different from the surrounding rock.
Minerals - How Minerals Form
More on Mineral Formation
• Click the PHSchool.com button for an
activity
about mineral formation.
Minerals - Using Mineral Resources
The Uses of Minerals
• Minerals are the source of
gemstones, metals, and a
variety of materials used to
make many products.
– Gemstone – a hard,
colorful mineral that has a
brilliant or glassy luster.
• Mainly used for decoration
and jewelry, but can be used
for grinding and polishing.
Minerals - Using Mineral Resources
Rubies
• Click the Video button to watch a movie
about rubies.
Minerals - Using Mineral Resources
The Uses of Minerals
– Metals – not as hard as
gemstones but can be
molded without breaking
• Used in building
supplies, tools, framings,
etc.
• People use materials from
these minerals in foods,
medicines, fertilizers, and
building materials.
Minerals - Using Mineral Resources
Producing Metals From Minerals
• To produce metal from a mineral:
– A rock containing the mineral must be located
through prospecting and mined (removed from
the ground)
– Then the rock must be processed to extract the
metal.
Minerals - Using Mineral Resources
Producing Metals From Minerals
• Ore – rock that contains a metal or
economically useful mineral.
• Prospector – anyone who searches, or
prospects, for an ore deposit.
• Once found, miners outline a plan for
digging up the ore. There are three types
of mines:
– strip mines, open pit mines, and shaft mines
Minerals - Using Mineral Resources
Producing Metals From Minerals
• Strip mine – large pieces of
equipment are used to scrape
away soil to expose ore
• Open pit – large pieces of
equipment are used to dig a
tremendous pit and remove ore
deposits
• Shaft mines - have a network
of tunnels that extend deep into
the ground, following the veins
of ore.
Minerals - Using Mineral Resources
Links on Mining Minerals
• Click the SciLinks button for links on
mining minerals.
Minerals - Using Mineral Resources
Producing Metals From Minerals
• Smelting – an
ore is mixed
with other
substances and
then melted to
separate the
useful metal
from the other
elements the
ore contains.
Minerals - Using Mineral Resources
Producing Aluminum
• Click the Video button to watch a movie
about
producing aluminum.
Minerals - Using Mineral Resources
Producing Metals From Minerals
• Once smelted, the impurities
will be removed.
• At this point some metals can
be melted together to form
alloys
• Alloy – a solid mixture of two
or more elements, at least one
of which is a metal.
– Ex: Steel
Minerals
Graphic Organizer
Hematite
Brick
Naturally
occurring
Crystal
structure
Definite
chemical
composition
Man-made
Solid
Inorganic
No crystal
structure
Chemical
composition
varies