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Minerals PowerPoint Lecture

Minerals PowerPoint Lecture



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Minerals Minerals Presentation Transcript

  • Minerals
  • What is a Mineral?
    • Naturally Occurring
    • Inorganic
    • Solid
    • Definite Chemical Formula
    • Definite Crystal Structure
  • Naturally Occurring
    • Formed by natural processes not in the laboratory.
      • Is an ice cube a mineral?
      • Is the ice on the windshield of a car a mineral?
      • Minerals manufactured by humans are not considered minerals.
  • Inorganic
    • Formed by inorganic processes; not living
    • Minerals are not made from living things.
    • Coal is made of carbon. Is it a mineral?
  • Solid
    • Minerals cannot be a gas or a liquid.
    - H 2 O as ice in a glacier is a mineral, but water is not.
  • Definite Crystal Structure
    • Highly ordered atomic arrangement of atoms in regular geometric patterns
    Apatite Feldspar Diamond Quartz
    • Minerals are crystals with a repeated inner structure.
  • Definite Chemical Formula
    • Minerals are expressed by a specific chemical formula.
    • Gold (Au)
    • Calcite (CaCO 3 )
    • Quartz (SiO 2 )
    • Pyrite (FeS 2 )
    • Minerals made of only one type of atom (element) are called native elements.
      • Gold
      • Copper
      • Silver
  • Types of minerals
    • Minerals are most commonly classified by chemical composition.
    • The 2 main groups are silicates and nonsilicates.
  • Silicates
    • Minerals containing a combination of silicon (Si) and oxygen (O) (most common elements in the earth’s crust)
    • Silicate minerals comprise about 90% of the Earth’s crust.
    • Silicates minerals often contain other elements such as aluminum, iron, magnesium, and potassium.
    • Granite is a rock comprised of the minerals feldspar, biotite mica and quartz.
  • Feldspar
    • Feldspar minerals make up half of the Earth’s crust and is the main component of most of the rocks found on the Earth’s surface.
    • Feldspar contains Si, O, Al, K, Na, and Ca
  • Biotite Mica
    • soft and shiny minerals that separate easily into sheets
    • biotite is one variety of mica
  • Quartz
    • silicon dioxide ( SiO 2 )
    • is the basic building block of many rocks
  • Nonsilicates
    • minerals that do not contain the combination of Si and O
    • some of these minerals are made up of C, O, F, and S
  • Classes of nonsilicates
    • Native Elements
    • Carbonates
    • Halides
    • Oxides
    • Sulfates
    • Sulfides
  • Native Elements
    • Native elements are composed of only 1 element
    • About 20 exist including Au, Pt, C, Cu, S and Ag
  • Carbonates
    • contain the combinations of carbon and Oxygen in their chemical structure
    • calcite (CaCO 3 ) is an example
    • carbonates are used in cement, building stones and fireworks
  • Halides
    • form when atoms containing fluorine, chlorine, iodine, or bromine (halogens) combine with potassium or calcium
    • Halite (NaCl) is better known as rock salt
    • Fluorite can have many different colors
    • Halides are often used in making fertilizers
  • Oxides
    • compounds formed when elements like aluminum or iron bond with oxygen
    • Corundum (Al 2 O 3 ) and Magnetite (Fe 3 O 4 ) are important oxides
    • Are used in abrasives and airplane parts
  • Sulfates
    • minerals containing sulfur and oxygen (SO 4 )
    • gypsum (CaSO 4 * 2H 2 O) is a common example
    • makes the white sand at White Sands National Monument in NM
    • sulfates are commonly used in cosmetics, toothpaste and paints
  • Sulfides
    • minerals containing one or more elements such as lead, iron, or nickel combines with sulfur
    • Galena (PbS) is a sulfide
    • Sulfides are used to make batteries, medicines and electronic parts
  • Composition of the Earth’s Crust
      • - Oxygen (O)
      • - Silicon (Si)
      • - Aluminum (Al)
      • - Iron (Fe)
      • - Calcium (Ca)
      • - Sodium (Na)
      • - Potassium (K)
      • - Magnesium (Mg)
      • Eight Elements that make up over 98% of Earth’s Crust
  • Where Do Minerals Come From? Magma Evaporation In general, minerals form in two ways: Cooling magma - Crystallization of melted materials From solution - Crystallization of materials dissolved in water At the surface Beneath the surface
  • Magma
    • Magma is molten material from the mantle that hardens to form rock.
    • Lava is magma that reaches the surface.
    • Minerals form as hot magma cools inside the crust, or as lava hardens on the surface.
    • When these liquids cool to the solid state, they form crystals.
  • Size of Crystals
    • Magma closer to the surface cools much faster, producing smaller crystals.
    • Slow cooling leads to the formation of large crystals.
    • When magma remains deep below the surface, it cools slowly over many thousands of years.
      • The chemical composition of the magma
      • The amount of gas the magma contains
      • The rate at which the magma cools
    • Depends of several factors:
  • Minerals from Hot Water Solutions
    • This can happen on the ocean floor when ocean water seeps down through cracks in the crust.
    • When a hot water solution begins to cool, the elements and compounds leave the solution and crystallize as minerals.
    • A solution is a mixture in which one substance dissolves in another.
    • Sometimes, the elements that form a mineral dissolve in hot water and form a solution.
  • Minerals formed by Evaporation
      • Gypsum
      • Calcite crystals
      • Minerals containing potassium
    • Several other useful minerals also from by the evaporation of seawater:
    • Minerals can also form when solutions evaporate. Example: salt from sea water
  • Minerals formed by Metamorphism
    • When rocks are put under extreme heat and pressure, the chemical composition of the rock can change, forming new minerals.
    • Examples: calcite, garnet, graphite, hematite, magnetite, mica and talc.
  • How Are Minerals Identified?
    • Color
    • Luster
    • Hardness
    • Streak
    • Density
    • Crystal Shape
    • Cleavage and Fracture
    • Special Properties
  • Color
    • Usually the first and most easily observed
    - Some minerals are the same color as others - Some minerals can have many colors
    • Not a reliable way to identify a mineral
  • Luster
    • General appearance of a mineral surface in reflected light
    Glassy- Obsidian
  • Examples of luster
    • Metallic
    • Greasy: resembles the way petroleum jelly or a greasy surface reflects light
    • Silky: resembles the way silk reflects light
    • Earthy: dull, may be rough or dusty
    • Waxy
    • Adamantine: resembles the way a diamond shines
    • Vitreous: similar to glass
    • Resinous: resembles the way plastic reflects light
    • Pearly: resembles the way pearls shine
    • Pitchy – looks like tar
    • Fibrous – looks like fibers
  • Hardness
    • Resistance to scratching by different items; “scratchability”
    • Mohs Hardness Scale is used to determine the hardness of minerals by comparing them to substances of known hardness:
      • < 2 fingernail
      • 3 penny
      • ~ 5 Steel of a pocket knife
      • 5.5 Window Glass
      • 6.6 Steel of a file
      • 7 Quartz crystal
  • Mohs Mineral Hardness Scale
    • 1) Talc
    • 2) Gypsum
    • 3) Calcite
    • 4) Flourite
    • 5) Apatite
    • 6) Feldspar
    • 7) Quartz
    • 8) Topaz
    • 9) Corundum
    • 10) Diamond
    Softest Hardest 1 2 3 4 5 6 7 8 9 10
  • Streak
    • The color of a finely powdered mineral
    • Determined by rubbing the mineral on a piece of unglazed porcelain (streak plate)
  • Density
    • The amount of matter in a given space
    • Specific Gravity is the comparison of a substance’s density to the density of water
  • Crystal Shape
    • Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming
  • Cleavage and Fracture
    • Cleavage is the tendency of a mineral to split or crack along parallel or flat planes
    • Fracture occurs when a mineral breaks at random lines instead of at consistent cleavage planes.
    Obsidian No Cleavage 1 Direction of Cleavage Conchoidal Fracture BIOTITE QUARTZ
  • Fracture
  • Special Properties
    • Magnetism (Magnetite)
    • Taste (Halite)
    • Smell (Sulfur)
    • Reaction to HCl (Calcite)
    • Double refractive - a thin, clear piece of calcite placed over an image will cause a double image
    • Radioactivity - minerals containing radium or uranium can be detected by a Geiger counter
    • Glowing under ultraviolet light (Fluorite)
  • Economic Importance of Minerals
    • Minerals are in many things we see and use everyday such as; bricks, glass, cement, plaster, iron, gold
  • Every American Requires 40,000 Pounds of New Minerals per Year
    • at this level of consumption the average newborn infant will need a lifetime supply of:
    • -795 lbs of lead (car batteries, electric components)
    • -757 lbs of zinc (to make brass, rubber, paints)
    • -1500lbs of copper (electrical motors, wirings
    • -3593 lbs aluminum (soda cans, aircraft)
    • -32,700 lbs of iron (kitchen utensils, automobiles, buildings)
    • -28,213 lbs of salt (cooking, detergents)
    • -1,238,101 lbs of stone, sand, gravel, cement (roads, homes, etc.)