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

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,

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

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

Minerals in sediment Sandy and clayey soils

Quartz

Na Plagioclase

QuartzFeldsparClayCalciteHematite

Sediments of:

Rocks (at surface) Sediment Weathered to form

Biotite

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

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

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

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

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

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

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

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