Chapter 5 Minerals of Earth

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Chapter 5Minerals of Earths Crust
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Define Mineral.Give one example.
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Section 1 What Is a Mineral?

• Minerals are
• Naturally occurring,
• Usually inorganic solid,
• Characteristic chemical composition,
• Orderly internal structure,
• Characteristic set of physical properties.

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Four basic questions
Section 1 Characteristics of Minerals

• 1. Is the substance inorganic?
• 2. Does the substance occur naturally?
• 3. Is the substance a solid in crystalline form?
• 4. Does the substance have a consistent
  chemical composition?
• See Table 1 page 103

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Section 1 Kinds of Minerals

• More than 3000 known minerals
• Fewer than 20 common minerals

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Section 1 Kinds of Minerals

• 10 common minerals make up 90 of the mass of the
  Earths crust.
• All minerals can be classified into 2 types.
• Silicates
• Nonsilicates

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Rocks are aggregates(mixtures of minerals)
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Silicate Minerals
Chapter 5
Section 1 Kinds of Minerals

• A mineral that contains a combination of silicon
  and oxygen, and that may also contain one or more
  metals
• Common silicate minerals include quartz,
  feldspars, micas ,and ferromagnesian minerals,
  such as amphiboles, pyroxenes, and olivines.

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Nonsilicate Minerals
Section 1 Kinds of Minerals

• A mineral that does not contain compounds of
  silicon and oxygen
• Nonsilicate minerals comprise about 4 of Earths
  crust.
• Examples Dolomite, Halite, Silver, Corundum,
  Calcite, Gypsum, Pyrite, and Galena.
• See Table 2 Page 105
• Skip Pages 106-108

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Mineralogists
Section 2 Identifying Minerals

• A person who examines, analyzes, and classifies
  minerals.

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Physical Properties of Minerals
Section 2 Identifying Minerals

• Many properties can be identified by just looking
  at a sample of the mineral.
• Other properties must be identified through
  simple tests.

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Five special properties that may help identify
certain minerals
Section 2 Physical Properties of Minerals

• Color
• Streak
• Luster
• Cleavage and Fracture
• Hardness

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Color

• While color is a property that is easily
  observed, it is unreliable for the identification
  of minerals.
• The color of a mineral sample can be affected by
  the inclusion of impurities or by weathering
  processes.

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Color-

• These are all quartz with different minerals in
  them.

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Streak- the color of a mineral in powdered form

• Streak is determined by rubbing some of the
  mineral against an unglazed ceramic tile called a
  streak plate.
• Much more reliable than color.
• The streak may differ from the solid color of the
  mineral.
• Minerals harder than the ceramic tile will leave
  no streak.

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Streaks
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Luster

• A mineral is said to have a metallic luster if
  the mineral reflects light as a polished metal
  does.
• All other minerals have nonmetallic luster.
• There are several types of nonmetallic luster,
  including glassy, waxy, pearly, brilliant, and
  earthy.

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Luster- the way in which a mineral reflects
light
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Cleavage and Fracture

• Cleavage- the tendency of a mineral to split
  along specific planes of weakness to form smooth,
  flat surfaces
• Fracture- the manner in which a mineral breaks
  along either curved or irregular surfaces

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Cleavage-
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Fracture-
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Hardness

• Hardness is a measure of a minerals ability to
  resist scratching.
• Hardness does not mean it will not break.
• Mohs hardness scale the standard scale against
  which the hardness of minerals is rated.

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• Crystal Shape

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Density
Chapter 5

• Is the ratio of the mass of the mineral to the
  volume of the mineral.
• Some minerals feel heavier than others.