Properties of Minerals

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Table of Contents

• Properties of Minerals
• How Minerals Form
• Using Mineral Resources

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What Is a Mineral?
- Properties of Minerals

• 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
• Naturally occurring substance cannot be man
  made
• Inorganic - the substance cannot form from
  materials that were once part of a living thing

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What Is a Mineral?

• 3. Solid substance must be a solid with a
  definite volume and shape
• Crystal - a solid in which the atoms are arranged
  in a pattern that repeats again and again
• Definite Chemical Composition the substance
  always contains certain elements in definite
  proportions

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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

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Identifying Minerals

• Streak the color of a minerals powder.
• Observe a streak by rubbing a mineral against a
  piece of unglazed porcelain tile
• Streak color and mineral color are often
  different.

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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

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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.

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Calculating Density
- Properties of Minerals

• 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

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Calculating Density
- Properties of Minerals

• 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

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Identifying Minerals

• Hardness refers to the minerals ability to
  resist scratching.
• Mohs hardness scale ranks ten minerals from
  softest to hardest

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• Talc 1 Easily scratched by fingernail
• Gypsum 2 Can be scratched by fingernail
• Calcite 3 Can be scratched by copper penny
• Fluorite 4 Easily scratched with steel
  file/glass
• Apatite 5 Easily scratched with steel file/glass
  
• Feldspar 6 Scratches glass with difficulty
• Quartz 7 Easily scratches both glass and steel
• Topaz 8 Scratches quartz
• Corundum 9 No simple tests
• Diamond 10 Scratches everything

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Identifying Minerals

• Crystal systems - crystals of each mineral grow
  atom by atom to form that minerals crystal
  structure.
• Classified into six groups based on the number
  and angle of the crystal faces
• Cleavage minerals ability to split easily
  along flat surfaces.
• Fracture the way a mineral looks when it breaks
  apart in an irregular way.

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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

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Identifying Minerals
- Properties of Minerals
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Mineral Density
- Properties of Minerals

• Use the line graph of the mass and volume of
  pyrite samples to answer the questions.

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Mineral Density
- Properties of Minerals

• Reading Graphs
• What is the mass of Sample B? What is the volume
  of Sample B?

• 50 g 10 cm3

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Mineral Density
- Properties of Minerals

• Calculating
• What is the density of Sample B?

• 5 g/cm3

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Mineral Density
- Properties of Minerals

• Reading Graphs
• What is the mass of Sample C? What is the volume
  of Sample C?

• 100 g 20 cm3

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Mineral Density
- Properties of Minerals

• Calculating
• What is the density of Sample C?

• 5 g/cm3

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Mineral Density
- Properties of Minerals

• Comparing and Contrasting
• Compare the density of Sample B to that ofSample
  C.

• The density of samples B and C is the same.

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Mineral Density
- Properties of Minerals

• Predicting
• A piece of pyrite has a volume of 40 cm3. What is
  its mass?

• 8 g

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Mineral Density
- Properties of Minerals

• 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.

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Crystal Systems Activity
- Properties of Minerals

• Click the Active Art button to open a browser
  window and access Active Art about crystal
  systems.

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Data Sharing Lab
- Properties of Minerals

• Click the PHSchool.com button for an activity
  about sharing data for the Skills Lab Finding the
  Density of Minerals.

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Where Minerals Form
- How 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.

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Where Minerals Form
- How 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.

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Minerals From Solutions
- How Minerals Form

• 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

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- 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.
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More on Mineral Formation
- How Minerals Form

• Click the PHSchool.com button for an
  activityabout mineral formation.

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The Uses of Minerals
- Using Mineral Resources

• 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.

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Rubies
- Using Mineral Resources

• Click the Video button to watch a movie about
  rubies.

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The Uses of Minerals
- Using Mineral Resources

• 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.

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Producing Metals From Minerals
- Using Mineral Resources

• 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.

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Producing Metals From Minerals
- Using Mineral Resources

• 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

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Producing Metals From Minerals
- Using Mineral Resources

• 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.

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Links on Mining Minerals
- Using Mineral Resources

• Click the SciLinks button for links on mining
  minerals.

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Producing Metals From Minerals
- Using Mineral Resources

• Smelting an ore is mixed with other substances
  and then melted to separate the useful metal from
  the other elements the ore contains.

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Producing Aluminum
- Using Mineral Resources

• Click the Video button to watch a movie
  aboutproducing aluminum.

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Producing Metals From Minerals
- Using Mineral Resources

• 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

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Graphic Organizer
Hematite
Brick
Naturally occurring
Man-made
Solid
Crystal structure
No crystal structure
Inorganic
Chemical composition varies
Definite chemical composition