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Important Economic Minerals
Elements: Gold, Copper, Zinc… Sulfur Diamond, Graphite,
Iron Oxides: Hematite (Fe2O3), Magnetite (Fe3O4)
Elements and Ores Usually concentrated by
biological or hydrothermal processes
Associated with volcanism (plutonics) or metamorphism
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Rock-Forming Minerals
Sediments and Sedimentary Rocks Oxides (e.g., Iron oxides)
Fe2O3, Fe3O4
Halides (e.g., with Cl- or S-2) NaCl, FeS2
Sulfates (SO4)-2 and Carbonates (CO3)
-2
FeSO4, CaSO4, CaSO4,·(2H2O)
CaCO3, CaMg(CO3)2,
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Fig. 2.9 From bottom to
top Increasing
Fe/Mg/Ca Decreasing silica Increasing density Darker minerals Decreasing
Silica
29% 14%
<20% 20%
<3% 23%
<2% 25%
(0) 33% (0) 23% (0) 15%*
% of Tot. # of atoms Fe/Mg: Silicon:
IncreasingFe/Mg/Ca Quartz
K and Na Feldspar
Ca Feldspar
Systematic SilicateMineralogy
IncreasingDensity
Olivine
PyroxeneGroup
AmphiboleGroup
MicaGroup
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Fig. 2.9 From bottom to
top Increasing
Fe/Mg/Ca Decreasing silica Increasing density Darker minerals
• Fe/Mg/Ca Content • Density
• Susceptibility to Weathering*
Quartz
K and Na Feldspar
Ca Feldspar#
Systematic Silicate Mineralogy and Engineering Properties Olivine
PyroxeneGroup
AmphiboleGroup
MicaGroup
• Melting and crystallizing
Temperature~
Increasing
Decreasing
*All of these silicates weather to form Clay MineralsExcept quartz
~Quartz melts first
Mantle
OceanicCrust#
Cont.Crust
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Minerals in sediment Sandy and clayey soils
Quartz
Na Plagioclase
QuartzFeldsparClayCalciteHematite
Sediments of:
Rocks (at surface) Sediment Weathered to form
Biotite
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Minerals in Rocks Clastic sedimentary rocks E.g., Sandstone
Primary minerals: Quartz and Feldspar
Secondary mineral from weathering: Clay and Oxides
Lithified (Compacted and cemented together)
From Sand deposited by a
river or beach
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Minerals in Rocks Biochemical and bioclastic sedimentary
Shells, Coral, Calcite and Dolomite in Limestone Lithified lime mud
and Shell fragments Crystalline or
Bioclastic
Shells, Coral, Calcite and Dolomite in Limestone Lithified lime mud
and Shell fragments Crystalline or
Bioclastic
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Minerals in Rocks Clastic sedimentary rocks
E.g., Shale Primary mineral:
Clay Minor mineral
Quartz and Feldspar and Oxides
From mud
deposited in a deep lake, sea or ocean
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Minerals in Rocks Metamorphic
E.g. Schist Mica, Quartz and Feldspars Interlocking
crystals (i.e., crystalline)
Shale metamorphosedMinerals Changed
in the solid state by heat and pressure
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Minerals in Rocks Intrusive igneous rocks
E.g., granite Quartz, Feldspar
and a few Ferromagnesian minerals
Tightly interlocking crystals (crystalline)
Minerals formed
from crystallizing
magma
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IV. Igneous Rocks
A. Igneous Rocks and the Rock CycleB. Basaltic Volcanism and Volcanic Rocks (extrusive igneous rocks)
C. Silicic Volcanism and Volcanic RocksD. Intrusive Igneous Rocks and E. Igneous Rock Classification
A. Igneous Rocks and the Rock CycleB. Basaltic Volcanism and Volcanic Rocks (extrusive igneous rocks)
C. Silicic Volcanism and Volcanic RocksD. Intrusive Igneous Rocks and E. Igneous Rock Classification
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A. Igneous Rocks and The Rock Cycle
Igneous Rock
Solidification
Magma
Partial Melting
Mantle Rock Fig 3.1
Geological Materials
Transformation Processes
See Kehew, Fig 2.53
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Fig. 2.9 From bottom to
top Increasing
Fe/Mg/Ca Decreasing silica Increasing density Darker minerals
29% 14%
<20% 20%
<3% 23%
<2% 25%
(0) 33% (0) 23% (0) 15%*
% of Tot. # of atoms Fe/Mg: Silicon:
Quartz
K and Na Feldspar
Ca Feldspar
Melting Points ofSilicate Minerals
IncreasingMelting
Temperature
Olivine
PyroxeneGroup
AmphiboleGroup
MicaGroup
<700oC
> 1,100oC