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Minerals of the Earths Crust

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Title: Minerals of the Earths Crust


1
Minerals of theEarths Crust
  • What is a Mineral?
  • Identifying Minerals

2
Thought Questions
  • What is a mineral? Name two minerals you know.
  • How do minerals form?
  • What elements do you think are most commonly
    found in minerals?

3
Chapter 4 Objectives
  • Distinguish between the two main mineral groups
  • Identify the elements most abundantly found in
    common minerals
  • Name six types of nonsilicate minerals
  • Distinguish among the six main arrangements of
    silicon-oxygen tetrahedra found in silicate
    minerals
  • Describe some characteristics that help
    distinguish one mineral from another
  • List four special properties that help to
    identify certain minerals

4
What is a Mineral?
  • Mineral- the basic material that make up the
    rocks and crust of the earth naturally
    occurring,usually inorganic, with a specific
    chemical composition, an orderly chemical
    structure, and specific characteristic properties
  • Inorganic-non-carbon bearing material not made
    of or from living organisms or once living
    organisms

5
Mineral or Not?
  • To determine if a substance is a mineral, it must
    fit into four basic categories. Mineralogists ask
    the following four questions to identify
    minerals
  • Is the substance inorganic?
  • Does the substance occur naturally?
  • Is the substance solid with a regular crystalline
    form?
  • Does the substance have a regular, repeating
    chemical composition?

6
How Minerals Form
  • There are four ways that minerals form
  • Crystallization within magma (i.e. tourmaline,
    olivine, quartz, feldspar)
  • Precipitation from solution (salt flats)
  • Changes in pressure or temperature
  • Formation form hydrothermal solutions

7
Mineral Characteristics
  • Definite Crystalline Structure
  • At times and fairly rare, a mineral will form in
    an open space and grow into one large crystal,
    possibly taking the shape of one of the six major
    crystal systems.

8
Classifying Minerals
  • Rock-Forming Minerals-minerals that form the
    rocks of the earths crust 20 total 10 make up
    90 of the earths crust (quartz, orthoclase,
    plagioclase, muscovite, biotite, calcite,
    dolomite, halite, gypsum, and ferromagnesian
    minerals)
  • Two major groups based on chemical composition
  • Silicates-minerals that contain silicon and
    oxygen 96 of earths crustal rocks
  • Nonsilicates-minerals that do not contain any
    silicon only 4 of the earths crustal rocks
    organized into 6 major groups

9
Mineral Groups
10
Some Rock-Forming Minerals
Muscovite
Plagioclase Feldspar
Orthoclase Feldspar
11
Major Classes of Nonsilicates
Calcium Carbonate
Carbonates - Contain carbonate group, CO3 Halides
- Compounds that have The metals Sodium,
Potassium, or Calcium combined with Chlorine or
Fluorine Native Elements - Elements found pure in
nature. Oxides - Compounds with Oxygen and an
element other than Silicon. Sulfates - Compounds
containing sulfate, SO3. Sulfides - Compounds
that consist of one or more elements combined
with sulfur.
Fluorite (halide)
Copper Ore (native element)
Hematite (oxide)
Gypsum (sulfate)
Pyrite (sulfide)
12
Non-Silicate Examples
13
Crystalline Structure
  • Crystal-any solid whose atoms, ions or molecules
    are arranged in a regular, repeating pattern
  • Silicon-Oxygen Tetrahedron-the base crystalline
    structure that makes up all silicate minerals
    arranged in six basic structures
  • Isolated Tetrahedra
  • Ring Silicates
  • Single Chain Silicates
  • Double Chain
  • Sheet Silicate
  • Framework Silicates

14
Mineral Groups
  • Silicates
  • One silicon atom attaches to four oxygen atoms to
    form a silica tetrahedron, a three-dimensional
    shape structured like a pyramid.
  • The basic silica tetrahedron has the ability to
    share oxygen atoms with other tetrahedron
    molecules.
  • This allows the molecules to combine chemically
    and structurally in a vast number of ways.

15
Mineral Groups
  • Silicates
  • Some possible arrangements formed by silica
    tetrahedrons include single chains, double
    chains, and sheets.

16
Section Assessment
  • Match the following terms with their
    definitions.
  • ___ mineral
  • ___ crystal
  • ___ magma
  • ___ silicate

B C D A
A. minerals that contain silicon and oxygen, and
usually one or more other elements B. a naturally
occurring, inorganic solid with a specific
chemical composition and definite crystalline
structure C. a solid in which the atoms are
arranged in repeating patterns D. molten material
found beneath Earths surface
17
Section Assessment
  • Identify whether the following statements are
    true or false.

_______ There are about 30 common minerals in
Earths crust. _______ Slowly cooling magma
produces small crystals. _______ Coal is a
mineral. _______ Silicates are the most common
minerals on Earth. _______ Well-defined crystal
shapes are rare.
true false false true true
18
Studying Minerals
  • Mineralogist-Geoscientist that examine, analyze,
    and classify minerals
  • Physical Properties of Minerals All minerals
    have a specific set of characteristic properties
    unique to that mineral bases on the chemical
    composition and crystalline structure there are
    seven distinguishing properties

19
Seven Mineral Characteristics
  • Color- the color of the mineral
  • Streak-the color of the mineral in powder form
    observed by rubbing the mineral against an
    unglazed ceramic tile (streak?color)
  • Luster-the light that is reflected from a
    minerals surface
  • Metallic-highly reflective, shiny (like polished
    metal)
  • Nonmetallic-dull, non reflective material
  • Cleavage-the tendency of a mineral to break/split
    along specific planes of weakness to form smooth,
    flat surfaces often expressed as an angle degree

20
Color, Luster and Cleavage
Quartz comes in a variety of colors
Metallic and Dull Luster
Fracture
Examples of mineral cleavage
21
More Mineral Characteristics
  • Fracture-minerals that break in inconsistent
    patterns, forming irregular, uneven pieces with
    curved or jagged edges
  • Hardness-the measure of the ability of a mineral
    to resist surface scratches independent of
    fracture or cleavage
  • Mohs Hardness Scale-the standard scale against
    which the hardness of minerals is tested bases
    on 1-10 with 1 the softest and 10 being the
    hardest

22
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23
Last of the Characteristics
  • Crystalline Shape-all minerals form in one of six
    basic shapes specific minerals always form the
    same crystalline shape
  • Density-the ratio of the mass of a substance to
    its volume specific to mineral type

24
Special Mineral Properties
  • Fluorescence-minerals that glow under
    ultraviolet light
  • Phosphorescence-rocks that continue to glow
    even after an ultraviolet light is removed
  • Magnetism-some minerals are magnetic

25
More Special Properties
  • Refraction-transparent minerals that bend light
    as it passes through the mineral creating a view
    through the mineral
  • Double refraction-two images produced
  • Radioactivity-minerals whose atoms are unstable
    release high energy particles
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