Chapter 3: Minerals
Earth Science
6th grade
BELL WORK
• Mineral: a naturally occurring, inorganic solid
that has a crystal structure and a definite
chemical composition.
• Silicate: mineral formed from elements oxygen
and silica
• Crystallization: the process by which atoms are
arranged to form a mineral with a crystal
structure
• Magma: molten mixture of rock-forming
substances , gases, and water from the mantle
• Lava: liquid magma that reaches the surface.
Also, the rock formed when liquid lava
Get ready to read…
Predictions!
• A mineral is anything solid on Earth.
• Some minerals form when water evaporates
from Earth’s surface.
• The best way to identify a mineral is by color.
• Hardness, streak, and luster are among the
properties used to identify minerals.
• An ore is a concentration of minerals that
contains only iron.
• Gemstone and ore deposits are evenly
distributed around the world.
Lesson 1: What is a mineral?
• What is a mineral?
• What are the common rock-forming
minerals?
• How do minerals form?
Are rocks and minerals the
same? (LaunchLab p. 77)
• Rocks generally contain two or more minerals
• Minerals are made of one uniform substance
• Work in pairs
– Group objects according to similar characteristics
• Try to have your partner guess what characteristic you used
– Alternate grouping of objects
• Use different characteristics each time
– Finally work together
• Group all objects you think are made of one uniform
substance
• Second group of objects you think are made of more than one
substance
What is a mineral?
• A naturally occurring,
inorganic solid with a
definite chemical
composition and an
orderly arrangement of
atoms or ions
• We use minerals in
every day life, they are
ingredients in common
things we use.
Three kinds of Quartz
Properties of minerals
• Naturally occurring (not made in lab)
– 4,000 minerals on earth (30 are common)
• 10 are called rock-forming
– Examples: quartz, feldspar and olivine
• Definite chemical composition
– Hematite: Fe2O3
• Two parts Iron, three parts Oxygen
• Anything with this ratio of these elements= hematite
– Some minerals only have one element= native element
• Examples: Silver (Ag), Sulfur (S)
Properties of minerals cont’d
• Crystalline forming
– Minerals form predictable
crystal patterns
• Determined by arrangement of
atoms or ions
– Example: Salt crystals form
cubes
– Halite: salt you shake on your
food
– No crystalline shape= not a
mineral
• Solid
– All minerals are solid
• Tightly packed atoms or ions
• Definite shape and volume
Quartz
Properties of minerals
cont’d
• Inorganic
– Not from
biological origins
• Can result from
biological
processes
– Organisms can
make a shell but
the shell itself is
not biologically
derived
Shell of Calcite crystals
What are the five main
characteristics of minerals?
•
•
•
•
•
Naturally occurring
Definite chemical composition
Crystal structure
Solid
Inorganic
The Structure of Minerals
• All minerals have a
crystalline
arrangement
– Shape can differ
• Crystal shape can
develop
– Right conditions
– Time to grow
• Sometimes crystals
don’t grow in large
shapes, sometimes
tiny (need microscope
to see)
Crystal structure of NaCl
How can you tell crystals
apart? (MiniLab. page 80)
• Compare two kinds of salt
– Halite (also called rock salt)
• Mineral in table salt
– Epsom salt
• Magnesium sulfate
•
•
•
•
•
Pour some halite onto dark construction paper
Observe with magnifying lens
Draw shape in Science Journal
Repeat with Epsom salt
Compare two drawings/shapes
– What are the differences?
Common Minerals
• Common rockforming minerals
composed of
combinations of
elements
– Two most
common
elements
• Oxygen & Silicon
• Quartz= formed of
only oxygen and
silicon (silicate) =
SiO2
Two main families of rockforming minerals
• Silicates: member
of the mineral
group that has
silicon and oxygen
in its crystal
structure
– Feldspar= most
common silicate
mineral
• Non-silicates: do
not contain silicon.
• Calcite and Halite
How do minerals form?
• ALL minerals form through crystallization
– Particles dissolved in a liquid or a melt solidify
and form crystals
• From hot OR cold solutions
– Halite= forms from cool solution. Water with halite solids
evaporate and leaves halite crystal behind.
Minerals from cool solutions
• Rain or snow causes water to enter the
ground or flow over surface
– Water interacts with minerals
• Dissolves minerals
• Picks up elements (K+, Ca2+, Fe3+, Si4+)
– Become dissolved solids
• Water evaporates
– Solids in water crystallize
• Form minerals
• Too much solid in water (salt for example)
– Organisms use the salt to make shells or build
reefs
Minerals from hot solutions
• Water in deep/hot
environments
– Large concentration
of solids
– Solids can form
deposits
• Gold crystallized from
hot water solution in
cracks of rock
Vein (brown) contains gold.
Toi gold mine, Japan
Minerals from Magma
• Magma: molten rock stored
beneath earth’s surface
– Lava (or ash): when that
same molten rock erupts
on/near earth’s surface
• When magma or lava cools
it forms mineral crystals
– Atoms and ions rearrange
themselves
– Crystal size depends on how
fast it cooled
• Small= when lava cools quickly
• Large= when magma cools
slowly
Changes in Minerals
• Depend on temperature and pressure
conditions
– Minerals formed at high temperature pressure are
stable at those conditions
• Change to low temperature and low pressure and
minerals can break down
– Minerals formed deep within Earth’s crust/mantle then
move to surface
• Elements can also break down minerals
– Water, wind, ice
– Broken down minerals can form new minerals
HOMEWORK
• Vocabulary words on flash cards
– Memorize for quiz
• Outline Lesson 1
• Page 84 (Lesson 1 review)
– Questions 1-9
BELL WORK
• Mineralogist: Scientists who study the distribution of
minerals, mineral properties, and their uses
• Luster: the way a mineral reflects light from its
surface.
• Streak: the color of a mineral’s powder.
• Hardness: resistance of a mineral to being scratched
• Cleavage: a mineral’s ability to split easily along flat
surfaces.
• Fracture: the way a mineral looks when it breaks
apart in an irregular way.
• Density: the amount of mass of a substance in a
given volume
Lesson 2: How are minerals
identified?
• Why is it necessary to use more than
one property for mineral
identification?
• What properties can you use to
identify minerals?
Can you grow crystals from a
solution? (LaunchLab p.87)
• In a small beaker add 20mL of hot water and
1teaspoon salt
– Label beaker “salt”
• Repeat the same process
– Alum, Epsom salt and washing soda
• Remove 5mL of solution with a dropper
– One clean dropper for each solution
• Place 5-10 drops of each solution on jar lid
– Make 4 separate puddles
– Make one mixed puddle
– Label each puddle
• Place lid in warm place- check at end of class
and at beginning of next class
Physical Properties
• Color
– Cannot be used alone
to identify a mineral
– Many minerals can
have the same color
– A single mineral can
have different colors
• Quarts: clear, white,
smoky gray, purple,
orange, or pink
– Variations in color
reflect different
chemical impurities
Physical Properties
• Luster: the way a mineral reflects or absorbs
light at its surface (related to chemical
composition)
• Metals reflect light
– Shiniest luster= metallic luster
– Examples: copper, silver, gold
• Nonmetallic minerals can be shiny (Not
reflective like metals) Example: diamond
• Other examples of luster (not shiny)
– Called earthy or dull
– Examples: Waxy, silky, pearly, vitreous (glassy)
Luster
Physical Properties
• Streak: color of a mineral in powdered form
– Rub a mineral across a scratch plate (unglazed
porcelain plate) sometimes leaves a colored streak
• Nonmetallics= usually white
• Metallics= characteristic streak
– Different colors of same mineral have same streak color
Physical
Properties
• Hardness: resistance
of a mineral to being
scratched. (Streak
relates to hardness)
– Friedrich Mohs
developed hardness
scale to compare
different minerals
• 1-10 [1= softest (talc),
10=hardest (diamond)]
– If rub two minerals
together, the softer one
will be scratched
Physical Properties
• Cleavage- if a mineral
breaks with smooth, flat
surfaces, it has
cleavage.
– Mineral breaks where
bonds between atoms are
weak
• Fracture- if a mineral
breaks and forms
uneven surface, it has
fracture.
– Unpredictable patterns
– Strong bonds between
atoms in all directions
Physical Properties
• Density: equal to mass
of an object divided by
it volume
– If objects are about the
same size (volume)
then compare how
heavy they are (mass)
– If one object is heavier
than the other, it has a
higher density
– Can use density to
compare minerals
Special Properties
• Texture
– Greasy (graphite) or smooth
(talc)
• Reactions
– HCl causes Calcite to fizz and
produce gas
• Odors
– Sulfur smells like a match
– Kaolinite smells like clay
• Fluorescence (glows under
UV light)
– Calcite and fluorite
• Magnetic properties
– Magnetite
ALL properties for
identifying minerals
•
•
•
•
•
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Color
Luster
Streak
Hardness
Cleavage/Fracture
Density
•
•
•
•
•
Texture
Reactions
Odors
Fluorescence
Magnetic
properties
How are cleavage and fracture
different? (MiniLab p.90)
• Work in pairs
• Separate minerals into two groups
– Minerals with cleavage
• Determine how many sets of parallel lines
each mineral has
– Each set= cleavage direction
– Minerals with fracture
• Describe surfaces in Science Journal
HOMEWORK
• Vocabulary words on flash cards
– Memorize for quiz
• Outline Lesson 2
• Page 92 (Lesson 2 review)
– Questions 1-8
BELL WORK
• Ore: Metallic mineral resource mined for a
profit
• Gemstone: Valuable minerals because
they are rare, beautiful and durable.
• Check on jar lids with puddles of solution
– Crystals present?
– What do they look like?
• Draw in Science Journal
Lesson 3: Sources and
Uses of Minerals
• How are minerals used in your daily
life?
• Why are minerals a valuable
resource?
Mineral Resources
• Minerals are in things we
use every day
– Copper= electrical wiring
– Quartz= glass and ceramics
• Some are more difficult to
find
• Ore= rock that contains
high enough
concentrations of a
desired substance, such
as a metal, so that it can
be mined for a profit.
Metallic
Mineral
Resources
• Iron and Aluminum
ores= most
abundantly used
Iron Ore
– Iron= hematite
(Fe2O3) and
magnetite (Fe3O4)
• Main ingredient in
steel
– Aluminum= Bauxite
(mixture of aluminum
and other elements)
• Aluminum cans
Aluminum
Rare Metals
• Gold
– 1:4,000,000,000
gold:rock
– Conducts electricity
– Does not corrode
(destroy/damage)
• Platinum
– Used in converters for
automobiles
Nonmetallic Mineral
Resources
• Use minerals that
are not ores
– Road construction,
ceramic products,
building stone,
fertilizers
• Sand
– Commonly
composed of quartz
(SiO2)
Gemstone
• Rare and
attractive
mineral that can
be worn as
jewelry
– Take on special
characteristics
when cut and
polished
How are minerals used in our
daily lives? (MiniLab p.98)
• Take two pieces of black paper
– One scoop of talc on one
– One scoop of sand on another
• Observe talc and rub it between fingers. Record
Observations in Science Journal.
• Dip damp paper towel into talk
– Rub nail with talc
• 20 strokes
– Record Observations in Science Journal
– Repeat with sand
• Compare how talc/sand felt between fingers
• Compare effect of talc/sand on nail
HOMEWORK
• Vocabulary words on flash cards
– Memorize for quiz
• Outline Lesson 3
• Page 99 (Lesson 3 review)
– Questions 1-10
BELL WORK
• Take out Science Journal
• Density determination
– Take notes
Determining Density (p.93)
• Density= mass/volume
– Measure mass
• Use balance
– Volume= equal to amount of water it displaces
– 1mL water= 1cm3
• Fill 100mL graduated cylinder with 50mL water
• Tie string around mineral
• Lower mineral into water (below surface but NOT touching
bottom)
• Read final volume of water
• Final volume- 50mL= volume of mineral
– You now have mass and volume, calculate density
• WATCH ME DO THIS
• Now can use this process for today’s lab
Mineral Detective (p.100)
• Work in groups
• Examine mineral
samples using:
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–
–
–
–
–
–
–
Magnifying lens
Magnet
Balance
Steel nail/Penny
Glass plate
5% HCl
Porcelain tile
100-mL graduated
cylinder
• Copy table into
Science Journal
– Fill out row for
each mineral and
answer all
questions
• Identify mineral
HOMEWORK
• Study guide (p. 103)
• Chapter 3 Review (p.104-105)
• Standardized Test Practice (p.106107)