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mineralogy final exam
sed and ore mins sed rocks optics
33
Geology
Undergraduate 3
12/11/2008

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Term
2:1:1 layer silicate
Definition
An octahedral layer sandwiched between 2 t-o-t structures.
Ex. Chlorite group
Term
2:1 layer silicate
Definition
An octahedral layer sandwiched between 2 tetrahedral layers
Ex. muscovite, vermiculite
Term
1:1 layer silicate
Definition
A singler tetrahedral sheet bonded to a single octahedral sheet.
Ex. kaolinite
Term
Halide Minerals
Definition
Min compounds characterized by a haolgen sucha as F, Cl, or I as an ion.
Term
Carbonate Minerals
Definition
Group of mins w/ formulas characterized by (CO3)2- radicals.
Term
mineralogical maturity
Definition
the degree to which unstable minerals have been removed from detritus by chem. weathering.
Term
textural maturity
Definition
measure of grain size, sort & roundness
Term
arenite
Definition
primarily composed of sandsized particles
Term
ore
Definition
any rock or min that can be extracted & sold for a profit
Term
reserve
Definition
amount of ore in a deposit
Term
ore grade
Definition
concentration of commodity in an ore
Term
disseminated deposit
Definition
ore mins scattered evenly throughout host rock.
Term
lode deposit
Definition
ore mins occur in many small veins throughout host rock
Term
porphyry deposit
Definition
occurs in closely spaced veins
Term
skarn deposit
Definition
ore associated w/ fluids that are active during contact metamorphism reactions btwn dissolved ions in aqueous fluids given off by intrusions w/ ions in country rock.
Term
wacke
Definition
sandstone containing lg. amounts of clay, rock frags or any other material w/ quartz.
"dirty sandstone"
Term
detrital
Definition
rocks formed by compaction & cementation of clast fragments of prexisting rock.
Term
hydrolysis
Definition
a type of weathering reaction that simultaneiously produces dissolved material & secondary minerals.
Term
diagenesis
Definition
transformation of deposited sediment into lithified rock. Includes chemical and biological processes
Term
oxidation
Definition
the process of an atom losing one or more electrons through chemical reaction
Term
supergene deposit
Definition
occurs when groundwater selectively dissolves ions in host rock, resulting in net concentration of ore mins. in "residue" host rock.
Term
epigenetic deposit
Definition
hydrothermal ore deposit whose formation is not associated w/ an igneous intrusion
Term
Index of refraction
Definition
when light passes into a crystal, the phase velocity decreases according to the crystals electron density.
Term
Analyzer
Definition
Allows only N-S vibrating component to pass==resolves 2 rays into 1 ray.
Term
Birefringence
Definition
numerical difference between the max RI & min RI
Term
pleochroism
Definition
preferential absorption of visable light wavelengths according to crystal orientation. --when you rotate the stage it will change the hue.
Term
banded iron deposit
Definition
"banded"===layers in host rock mostly in precambrian rock
Fe oxides
Fe carbonates
Fe silicate
Term
extinction position
Definition
birefringent mineral grain that appears "dark" when viewed under crossed polars.
Term
biaxial
Definition
mins have 2 optic axes
orthorhombic
monoclinic
triclinic
Term
uniaxial
Definition
mins have 1 optic axis
hexaganol
tetraganol
Term
optic axis
Definition
the direction along which the light vibrates in a crystal
Term
plane polarized light
Definition
light passed through polarizer.
Term
polarizer
Definition
allows light to pass vibrating in an E-W direction
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