Chapter 3: Minerals

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Chapter 3 Minerals

• Earth Science
• 6th grade

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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 hardens.

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Get ready to read Predictions!

• A mineral is anything solid on Earth.
• Some minerals form when water evaporates from
  Earths 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.

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Lesson 1 What is a mineral?

• What is a mineral?
• What are the common rock-forming minerals?
• How do minerals form?

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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

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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
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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)

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Properties of minerals contd

• 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
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Properties of minerals contd

• 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
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What are the five main characteristics of
minerals?

• Naturally occurring
• Definite chemical composition
• Crystal structure
• Solid
• Inorganic

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The Structure of Minerals

• All minerals have a crystalline arrangement
• Shape can differ
• Crystal shape can develop
• Right conditions
• Time to grow
• Sometimes crystals dont grow in large shapes,
  sometimes tiny (need microscope to see)

Crystal structure of NaCl
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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?

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Common Minerals

• Common rock-forming minerals composed of
  combinations of elements
• Two most common elements
• Oxygen Silicon
• Quartz formed of only oxygen and silicon
  (silicate) SiO2

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Two main families of rock-forming 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

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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.

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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

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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
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Minerals from Magma

• Magma molten rock stored beneath earths surface
  
• Lava (or ash) when that same molten rock erupts
  on/near earths 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

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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 Earths crust/mantle
  then move to surface
• Elements can also break down minerals
• Water, wind, ice
• Broken down minerals can form new minerals

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HOMEWORK

• Vocabulary words on flash cards
• Memorize for quiz
• Outline Lesson 1
• Page 84 (Lesson 1 review)
• Questions 1-9

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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 minerals powder.
• Hardness resistance of a mineral to being
  scratched
• Cleavage a minerals 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

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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?

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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

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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

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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)

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Luster
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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

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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), 10hardest (diamond)
• If rub two minerals together, the softer one will
  be scratched

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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

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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

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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

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ALL properties for identifying minerals

• Color
• Luster
• Streak
• Hardness
• Cleavage/Fracture
• Density

• Texture
• Reactions
• Odors
• Fluorescence
• Magnetic properties

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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

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HOMEWORK

• Vocabulary words on flash cards
• Memorize for quiz
• Outline Lesson 2
• Page 92 (Lesson 2 review)
• Questions 1-8

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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

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Lesson 3 Sources and Uses of Minerals

• How are minerals used in your daily life?
• Why are minerals a valuable resource?

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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.

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Metallic Mineral Resources

• Iron and Aluminum ores most abundantly used
• Iron hematite (Fe2O3) and magnetite (Fe3O4)
• Main ingredient in steel
• Aluminum Bauxite (mixture of aluminum and other
  elements)
• Aluminum cans

Iron Ore
Aluminum
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Rare Metals

• Gold
• 14,000,000,000 goldrock
• Conducts electricity
• Does not corrode (destroy/damage)
• Platinum
• Used in converters for automobiles

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Nonmetallic Mineral Resources

• Use minerals that are not ores
• Road construction, ceramic products, building
  stone, fertilizers
• Sand
• Commonly composed of quartz (SiO2)

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Gemstone

• Rare and attractive mineral that can be worn as
  jewelry
• Take on special characteristics when cut and
  polished

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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

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HOMEWORK

• Vocabulary words on flash cards
• Memorize for quiz
• Outline Lesson 3
• Page 99 (Lesson 3 review)
• Questions 1-10

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BELL WORK

• Take out Science Journal
• Density determination
• Take notes

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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 todays lab

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Mineral Detective (p.100)

• Work in groups
• Examine mineral samples using
• 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

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HOMEWORK

• Study guide (p. 103)
• Chapter 3 Review (p.104-105)
• Standardized Test Practice (p.106-107)