Earth Science, 10e
Edward J. Tarbuck &
Frederick K. Lutgens
Minerals: Building
Blocks of Rocks
Chapter 1
Earth Science, 10e
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
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
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
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
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Crystal form
Luster
Color
Streak
Hardness
Cleavage
Mineral Identification
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Color
2. Luster
Streak
4. Hardness
Cleavage
6. Fracture
Crystal form
8. Density
Specific gravity 10. Magnetism
Reaction to hydrochloric acid (HCl)
Taste
Fluorescence
Double refraction
The mineral quartz often
exhibits good crystal form
Pyrite (fool’s gold)
displays metallic luster
1.Color
not always diagnostic (feldspar, quartz, fluorite)
Feldspar can be green, pink white, gray, etc.
Three examples of perfect
cleavage – fluorite, halite,
and calcite
Cleavage
Breakage along planes. Related to crystal structure
1 direction
(muscovite, biotite)
Muscovite (left) Biotite (right)
2 directions at 90°
(feldspar, pyroxene)
Pyroxene
3 directions at 90° (cubic)
(halite, galena)
Halite
Galena
3 directions not at 90°(rhombohedral)
(calcite, dolomite)
Cleavage fragments of calcite
Cleavage fragments of dolomite
4 directions (octahedral)
6 directions
(fluorite)
(sphalerite)
Cleavage fragments of fluorite
Sphalerite
Minerals
Physical properties of minerals
• Fracture
• Specific gravity
• Other properties
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Taste
Smell
Elasticity
Malleability
Fracture
irregular breakage (no cleavage), breakage
not along smooth planes
Conchoidal fracture
smooth curved fracture surfaces
occurs in quartz, chert, obsidian, glass
Rose quartz and obsidian lacks cleavage;
they have conchoidal fracture
Conchoidal fracture
Minerals
Physical properties of minerals
• Other properties
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Feel
Magnetism
Double Refraction
Reaction to hydrochloric acid
Double refraction
Light passing through the mineral is split into two rays. Causes an optical
"doubling" effect.
Calcite
Calcite has the optical property of double refraction. In the photos above, the
same sample of calcite is used. It is rotated over a thin dark line. Examine how
the appearance of he line changes in the different orientations of calcite.
Mineral Formation
1. Magma formation- cooling of hot molten rock material
-Atoms lose energy and move closer together, patterns.
2. Liquid evaporation- minerals dissolved in liquids
-Liquid evaporates, atoms of minerals stay & form
crystals
3. Precipitation- alternate material in supersaturated
solutions
Minerals
A few dozen minerals are called the rockforming minerals
• The eight elements that compose most rockforming 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)
Minerals
Mineral groups
• Rock-forming silicates
• Most common mineral group
• Contain the silicon-oxygen tetrahedron
• Four oxygen atoms surrounding a much smaller
silicon atom
• Combines with other atoms to form the various
silicate structures
The silicate (SiO4)-4 molecule
Common silicate minerals
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
Some common non-silicate
minerals
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
The Bingham copper
mine in Utah
End of Chapter 1