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Lecture Outlines
PowerPoint
Chapter 2
Earth Science 11e
Tarbuck/Lutgens
Earth Science, 11e
Minerals: Building
Blocks of Rocks
Chapter 2
Minerals: the building
blocks of rocks
Definition of a mineral
• Natural
• Inorganic
• Solid
• Possess an orderly internal structure of atoms
• Have a definite chemical composition
Mineraloid - lacks an orderly internal structure
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
• Neutrons – neutral electrical charges
Energy levels, or shells
• Surround nucleus
• Contain electrons – negative electrical charges
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
How atoms are constructed
Isotopes
• Have different mass numbers – the sum of the
neutrons plus protons
• Many isotopes are radioactive and emit energy
and particles
Minerals
Physical properties of minerals
• Crystal form
• Luster
• Color
• Streak
• Hardness
• Cleavage
The mineral quartz often
exhibits good crystal form
Pyrite (fool’s gold)
displays metallic luster
Figure 2.10
Figure 2.12
Mohs scale
of hardness
Three examples of perfect
cleavage – fluorite, halite,
and calcite
Minerals
Physical properties of minerals
• Fracture
• Specific gravity
• Other properties
• Taste
• Smell
• Elasticity
• Malleability
Conchoidal fracture
Figure 2.15
Minerals
Physical properties of minerals
• Other properties
• Feel
• Magnetism
• Double Refraction
• Reaction to hydrochloric acid
Minerals
A few dozen minerals are called the rock-forming minerals
• The eight elements that compose most rock-forming minerals are oxygen (O), silicon (Si), aluminum (Al), iron (Fe), calcium (Ca), sodium (Na), potassium (K), and magnesium (Mg)
• Most abundant atoms in Earth's crust are oxygen (46.6% by weight) and silicon (27.7% by weight)
Composition of continental crust
Figure 2.16
Minerals
Mineral groups
• Rock-forming silicates
• Most common mineral group
• Contain the silicon-oxygen tetrahedron (molecule)
• Four oxygen atoms surrounding a much smaller
silicon atom
• Combines with other atoms to form the various
silicate structures
The silicate (SiO4)-4 molecule
Figure 2.17
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
