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Minerals

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Chapter 3 Minerals Minerals: naturally occurring, inorganic solids, with definite structure and composition; made of one or more elements Characteristics of Minerals ... – PowerPoint PPT presentation

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Title: Minerals


1
Chapter 3
  • Minerals

2
  • Minerals naturally occurring, inorganic solids,
    with definite structure and composition made of
    one or more elements
  • Characteristics of Minerals
  • Formed by natural processes
  • Inorganic (not formed from life processes)
  • Solid
  • Definite chemical composition, can have minor
    variations (example salt is NaCl)
  • Atoms arranged in a pattern

3
  • Structure of Minerals minerals are in the form
    of crystals (a solid in which the atoms are
    arranged in repeating patterns)
  • Crystal Systems Examples of Perfect Crystal
    Systems


Cubic Tetragonal
Hexagonal
Examples Cubic-Halite (salt) Platinum
Tetragonal-Zircon Wulfenite
Hexagonal-Quartz Corundum
4
CRYSTAL SYSTEMS are divided into 6 main groups.-
We will look at 3 groups
The first group is the ISOMETRIC. This literally
means equal measure and refers to the equal
size of the crystal axes.
ISOMETRIC - Fluorite Crystals
5
HEXAGONAL CRYSTALS
c
a
a3
a2
a1
HEXAGONAL Crystal Axes Three horizontal axes
meeting at angles of 120o and one perpendicular
axis.
These hexagonal CALCITE crystals nicely show the
six sided prisms
6
Hexagonal Crystals
7
TETRAGONAL CRYSTALS
TETRAGONAL Two equal, horizontal, mutually
perpendicular axes (a1, a2) Vertical axis (c) is
perpendicular to the horizontal axes and is of a
different length.
8
  • TETRAGONAL CRYSTALS

WULFENITE
Same crystal seen edge on.
9
How Minerals Form
  • Form from the cooling of hot melted rock (magma)
    If it cools fast, crystals tend to be small
    cools slow, larger crystals tend to form
  • Form from solutions-as liquid evaporates,
    minerals solidify and form crystals

10
Major Mineral Groups
  • Silicates-Made of Silicon, Oxygen, possibly
    other element(s) largest group of minerals
  • Example Quartz (SiO2)
  • Carbonates-Made of Carbon, Oxygen, possibly
    other element(s)
  • Examples Calcite (CaCO3)
    Magnetite (MgCO3)

11
Most Abundant Elements in Earths Crust
  • 1. Oxygen 46.6
  • 2. Silicon 27.7
  • 3. Aluminum 8.1
  • 4. Iron 5
  • 5. Calcium 3.6
  • 6. Sodium 2.8
  • 7. Potassium 2.6
  • 8. Magnesium 2.1
  • All other elements make up 1.5 of the
    Earths crust.

12
Physical Properties of Minerals
  • Hardness-a measure of how easily a mineral can be
    scratched

1 is the softest, 10 is the hardest 1 is the softest, 10 is the hardest 1 is the softest, 10 is the hardest
Mohs Scale of Hardness Mohs Scale of Hardness Mohs Scale of Hardness
Sample Element Hardness Common Objects
Talc 1 Fingernail (2.5) Copper penny (3.5) Iron Nail (4.5) Glass (5.5) Steel File (6.5) Streak Plate (7)
Gypsum 2 Fingernail (2.5) Copper penny (3.5) Iron Nail (4.5) Glass (5.5) Steel File (6.5) Streak Plate (7)
Calcite 3 Fingernail (2.5) Copper penny (3.5) Iron Nail (4.5) Glass (5.5) Steel File (6.5) Streak Plate (7)
Fluorite 4 Fingernail (2.5) Copper penny (3.5) Iron Nail (4.5) Glass (5.5) Steel File (6.5) Streak Plate (7)
Apatite 5 Fingernail (2.5) Copper penny (3.5) Iron Nail (4.5) Glass (5.5) Steel File (6.5) Streak Plate (7)
Feldspar 6 Fingernail (2.5) Copper penny (3.5) Iron Nail (4.5) Glass (5.5) Steel File (6.5) Streak Plate (7)
Quartz 7 Fingernail (2.5) Copper penny (3.5) Iron Nail (4.5) Glass (5.5) Steel File (6.5) Streak Plate (7)
Topaz 8 Fingernail (2.5) Copper penny (3.5) Iron Nail (4.5) Glass (5.5) Steel File (6.5) Streak Plate (7)
Corundum 9 Fingernail (2.5) Copper penny (3.5) Iron Nail (4.5) Glass (5.5) Steel File (6.5) Streak Plate (7)
Diamond 10 Fingernail (2.5) Copper penny (3.5) Iron Nail (4.5) Glass (5.5) Steel File (6.5) Streak Plate (7)
13
Luster
  • Describes how light is reflected from a minerals
    surface
  • Metallic
  • Nonmetallic
  • dull pearly silky glassy brilliant
    transparent
  • Waxy
  • Resinous (looks like freshly broken shellac)

14
Color
  • The color seen when looking at the surface of the
    mineral Least reliable property because many
    minerals can be many colors
  • Example Sulfur is pale yellow

15
Streak
  • The color of the mineral when its broken up in
    powdered form Use a porcelain tile to test
    Useful for softer minerals Minerals with a
    hardness greater than 7 do not leave a streak
  • Example Gold has a gray streak

16
The Way a Mineral Breaks
  1. Cleavage-When a mineral breaks along smooth, flat
    surfaces Example Mica
  2. Fracture-When minerals break with rough or jagged
    edges Example Quartz

17
Special Properties
  • Unusual or unique qualities Examples Magnetite
    is magnetic, Calcite has optical qualities, Jade
    has a bell-like ring when tapped, Halite has a
    salty taste, and Sulfur smells like rotten eggs

18
  • Uses of Minerals
  • Gems-Highly prized minerals because they are rare
    and considered beautiful the difference in a gem
    and the common form of a mineral can be slight

19
  • Ores-contain useful substances that can be mined
    for a profit
  • Examples Bauxite contains Aluminum
  • Hematite contains Iron
  • Sphalerite contains Zinc
  • Chalcopyrite contains copper

20
  • Strip Mining-Removing ore by digging at Earths
    surface usually results in a huge pit
  • Land Reclamation- mining companies are required
    to return soil and rock to open pit and cover it
    with topsoil then plant trees and grass

21
  • Asbestos-a mineral with threadlike, flexible
    fibers used as insulation and as fire protection
    has been shown to cause lung diseases including
    lung cancer
  • EPA (Environmental Protection Agency)-requires
    school officials to inspect buildings every six
    months flaking asbestos must be removed or
    sealed over

22
  • Minerals can contain other useful elements.
  • 1.Elements must be refined, or purified, from
    ores
  • 2. Some elements dissolve in fluids, travel
    through weaknesses in rocks, and in those
    weaknesses form mineral deposits called vein
    mineral deposits
  • 3. Titanium is useful element derived from the
    minerals limonite and rutile
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