Physical Properties Lecture Min Lab 1

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Physical Properties LectureMin Lab 1

• Penelope Morton, University of Minnesota, Duluth
• Jason Sturms, Graduate Student WVU
• Helen Lang, WVU
• John Tellers, Graduate Student WVU

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What is a Mineral?

• Naturally Occurring Substance
• Characteristic Chemical Composition
• has an orderly and repetitive atomic structure
• Inorganic
• Solid
• crystalline
• (varies within limits and can be represented
• by a chemical formula)

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Identifying Minerals

• Use
• Color
• Hardness
• Luster
• Streak
• Cleavage
• Density
• Habit
• Twinning
• Miscellaneous Properties

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Color

• Generally Unreliable because many minerals exist
  in several colors.
• Example Quartz may be
• Clear (mirror or the soul???)
• Black or brown (Smoky)
• Violet (amethyst)
• Pink (Rose)
• yellow (false topaz, lemon)
• Cloudy (milky)
• Minerals containing iron are often dark
• Minerals containing aluminum are often light
• Chemical impurities may also give color
• A good example of True color is malachite (green)
  from the Cu.

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Some Colors of Quartz
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Varieties of Hematite
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The fluorite on your left is fluorescing The
fluorite on your right is the correct color
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Luster

• The appearance of a mineral in reflected light.
• Many variations of luster, but we will use
  metallic and non-metallic.
• Metallic Mineral looks like a metal (shiny)
• Non-Metallic Mineral has a dull appearance
• Thats okay for the little kids but what are
  some other forms of luster???

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LUSTER

• Metallic or non-metallic
• Non-metallic vitreous or glassy silky
  resinous pearly greasy waxy, dull earthy

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Examples of metallic luster
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Example of non-metallic luster

• Vitreous--quartz

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Example of non-metallic luster

• Silky--example satinspar

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Example of non-metallic luster

• Resinous--sphalerite

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Example of non-metallic luster

• Pearly--Talc

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Example of non-metallic luster

• Dull--Kaolinite

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Example of non-metallic luster

• Earthy--Goethite (limonite)

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Example of non-metallic luster

• Waxy--serpentine

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Streak

• Streak is the color of a mineral when finely
  powdered
• Streak of a mineral is usually constant
• Colored streaks are usually important
• White streaks are generally unimportant
• If no streak is left, that particular mineral is
  harder than the streak plate

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Hardness

• See Handout

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Cleavage

• If a crystal breaks due to stress and the broken
  piece retains a smooth plane or crystal shape,
  the mineral has cleavage.
• Cleavage surfaces often reflect light well, all
  at once in a single flash
• Any mineral break that is not cleavage is termed
  a fracture.
• Cleavage can be confused with crystal faces (how
  the mineral grows).
• Crystal faces tend to form regular polygonal
  shapes, such as cubes and prisms.
• Again this is okay for 102 but where is the
  science behind it?
• Check out the handout

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Miscellaneous Properties

• A property that a mineral exhibits that few
  others exhibit.
• Fizzing when exposed to acid
• Magnetic
• Transparent
• Feel greasy
• Taste Salty
• Etc.

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1 - Calcite

• CaCO3
• Non-metallic
• White, colorless, yellow, etc
• Softer than penny, harder than fingernail (H 3)
• White Streak
• Clevage
• Fizzes with acid

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2 - Galena

• Metallic
• Silver-gray
• Hard as fingernail
• Dark gray streak
• Cleavage
• Very Heavy

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3 - Feldspar

• Non-metallic
• Gray, blue, pink, white
• Harder than glass
• White streak
• Cleavage
• Fine striations (thin wavy lines)

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4 - Pyrite

• Metallic
• Brass Yellow
• Scratches glass
• Greenish-black streak
• No cleavage
• Fools Gold

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5 - Amphibole

• Non-metallic
• Black or dark green
• Between 5-6
• Colorless streak
• Cleavage

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6 - Muscovite

• Non-metallic
• Colorless
• H 2.5
• Colorless streak
• Cleavage
• Transparent thin, flexible sheets

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7 - Fluorite

• Non-metallic
• Many colors
• Softer than glass
• White streak
• Cleavage
• Fluorescent (glows in black light)

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8 Olivine

• Non-metallic
• Green, yellow, black
• Scratches glass
• Colorless streak
• No cleavage
• Usually Olive green color

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9 - Quartz

• SiO2
• Non-metallic
• White, pink, gray, etc.
• Scratches glass
• White streak
• No cleavage, crystal face
• Hexagonal crystals (prismatic)

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10 - Halite

• NaCl
• Non-metallic
• Colorless, pink, or white
• Less than fingernail
• White streak
• Cleavage
• Salty, dissolves in water

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11 - Hematite

• Metallic or Non-metallic
• Dark red to red-brown
• Hard as glass
• Red or red-brown streak
• No cleavage
• Can be slightly magnetic

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12 - Kaolinite

• Non-metallic
• White, gray, yellowish
• Softer than fingernail
• White streak
• No cleavage

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13 - Magnetite

• Metallic
• Black
• Harder than glass
• Dark streak
• No cleavage
• Magnetic

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14 - Graphite

• C
• Metallic
• Gray
• Softer than fingernail
• Gray-black streak
• No cleavage
• Greasy feeling

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15 - Corundum

• Non-metallic
• White, blue (sapphire), brown, red (ruby)
• H 9
• No streak
• No cleavage, crystal face
• 6-sided crystals

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16 - Gypsum

• Non-metallic
• Pink or white
• Softer than fingernail
• White streak
• Cleavage
• Transparent plates, fibrous

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17 - Garnet

• Non-metallic
• Red, red-brown, yellow, green
• Harder than glass
• No streak
• No cleavage, crystal face
• 12- sided, conchoidal fracture