Transcript Minerals

Lecture Outlines
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Chapter 2
Earth Science 11e
Tarbuck/Lutgens
© 2006 Pearson Prentice Hall
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Earth Science, 11e
Minerals: Building
Blocks of Rocks
Chapter 2
EARTH SCIENCE 170, 171
B Murphy, G Ferguson
JAMIE BRAID
RM 2006
Email : [email protected]
Tutorials
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Collette Rennie
4-5pm Wednesdays / Thursdays
NH 120
Starting the 17th
Minerals: the building
blocks of rocks
Definition of a mineral
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Natural
Inorganic
Solid
Possess an orderly internal structure of atoms
Have a definite chemical composition
Mineraloid - lacks an orderly internal
structure
• Minerals and rocks are the basic
components of the Solid Earth
Composition and
structure of minerals
Elements
• Basic building blocks of minerals
• Over 100 are known
Atoms
• Smallest particles of matter
• Have all the characteristics of an element
Periodic table of the Elements
Figure 2.4
How atoms are constructed
Nucleus – central part of
an atom that contains
• Protons – positive
electrical charges,
properties
• Neutrons – neutral
electrical charges
Energy levels, or shells
• orbit nucleus
• Contain electrons –
negative electrical charges
Elements
• Made in stars
• building blocks of minerals
• made up of atoms,
– central nucleus (protons and
neutrons)
–orbiting electrons
Elements
• Numbered 1 to 92, depending on
protons
• 1 to 26 made during life of stars
• 27 to 92, in supernova
• protons dictate properties
• electrons more loosely bound,
• bonding of elements to form
Periodic table of the Elements
Figure 2.4
Simplified view of the atom
Figure 2.5
How atoms are constructed
Atomic number is the number of protons in
an atom's nucleus
Bonding of atoms
• Forms a compound with two or more elements
• Ions are atoms that gain or lose electrons
Isotopes
• Have varying number of neutrons
Periodic table of the Elements
Figure 2.4
END NIGHT CLASS
Octet Rule
• Elements most stable with 8
electrons in their outer shell
• most elements have < 8
• therefore they have a
tendency to bond
Types of bonds
• IONIC-transfer of electron
• COVALENT-shared electrons
• METALLIC-Common cloud of
shared electrons (metals)
• van der Waals-bonding between
adjacent molecules
Ionic bonding NaCl
COVALENT
Periodic table of the Elements
Figure 2.4
Composition of continental crust
Not oxygen in the
air
Figure 2.16
99.9%
Composition of Earth’s Crust
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O
Si
Al
Fe
Ca
Na
K
Mg
46.6 (wt%)
27.7
8.1
5.0
3.6
2.8
2.6
2.1
62.6 (atoms)
21.2
6.5
1.9
1.9
2.6
1.4
1.8
The silicate (SiO4)-4 molecule
Charge imbalance
Figure 2.17
Leggo building
block for the earth
Silicate tetrahedron
The physical properties
of minerals
Color and streak
crystal form
hardness
cleavage and fracture
specific gravity and density
hardness
Fe-Mg silicates
DARK
Non Fe-Mg silicates
Little Iron and Magnesium
The physical properties
of minerals
Color and streak
crystal form
hardness
cleavage and fracture
specific gravity and
density
The mineral quartz often
exhibits good crystal form
Pyrite (fool’s gold)
displays metallic luster
Figure 2.10
Mineral crystals
External shape = internal bonding
The physical properties
of minerals
Color and streak
crystal form
hardness
cleavage and fracture
specific gravity and density
hardness
Diamond (Hard) Graphite (Soft)
How on can we form both???
GOLD ~ soft
Mohs scale
of hardness
Figure 2.12
The physical properties
of minerals
Color and streak
crystal form
hardness
cleavage and fracture
specific gravity and density
Silicate tetrahedron
Physical Properties
Reflect internal weakness in
structure and chemical
Breaking weak bonds
Three examples of perfect
cleavage – fluorite, halite,
and calcite
Weak planes parallel to edges (analogous to splitting wood)
Most minerals are silicates
• Silicon and oxygen
in a tetrahedral
arrangement
• variety of metallic
ions bonded
Silicate tetrahedron
Silicate minerals
UNUSED
Conchoidal fracture
Figure 2.15
Minerals
Physical properties of minerals
• Fracture
• Specific gravity
• Other properties
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Taste
Smell
Elasticity
Malleability
Minerals
Mineral groups
• Rock-forming silicates
• Groups based upon tetrahedral arrangement
• Olivine – independent tetrahedra
• Pyroxene group – tetrahedra are arranged in
chains
• Amphibole group – tetrahedra are arranged in
double chains
Hornblende – a member of
the amphibole group
Minerals
Mineral groups
• Rock-forming silicates
• Groups based upon tetrahedral arrangement
• Micas – tetrahedra are arranged in sheets
• Two types of mica are biotite (dark) and
muscovite (light)
• Feldspars - Three-dimensional network of
tetrahedra
Minerals
Mineral groups
• Rock-forming silicates
• Groups based upon tetrahedral arrangement
• Feldspars
• Two types of feldspar are Orthoclase and
Plagioclase
• Quartz – three-dimensional network of
tetrahedra
Potassium feldspar
Plagioclase feldspar
Minerals
Mineral groups
• Rock-forming silicates
• Feldspars are the most plentiful mineral group
• Crystallize from molten material
• Nonsilicate minerals
• Major groups
• Oxides
• Sulfides
Minerals
Mineral groups
• Nonsilicate minerals
• Major groups
• Sulfates
• Carbonates
• “Native” elements
Native Copper
Minerals
Mineral groups
• Nonsilicate minerals
• Carbonates
• A major rock-forming group
• Found in the rocks limestone and marble
• Halite and gypsum are found in sedimentary rocks
• Many have economic value
Minerals
Mineral resources
• Reserves are already identified deposits
• Ores are useful metallic minerals that can be
mined at a profit
• Economic factors may change and influence a
resource
An underground halite (salt) mine
End of Chapter 2