Earth Materials Exam Three

what is refractory index

velocity of light through a crystal

what is Snell’s Law

n1(sin1) = n2(sin2)

what is relief

how much one mineral “stands out,” to another

which displays higher relief in thin section, quartz or garnet

garnet

is pleochroism in cross polarized light or plane polarized light

plane polarized light

what color is biotite in thin section

dark brown to light brown

wave interference is key to understanding what

interference colors

how do isotropic minerals appear in cross polarized light

black

how do anisotropic minerals appear in polarized light

interference colors are displayed

do you observe interference colors in plane polarized light or cross polarized light

cross polarized light

what is it called when light emits in a mineral and refracts into two rays to different amounts in different directions

double refraction

what are the 3 eras of mineral evolution

planetary accretion, crust and mantle reworking, biologically mediated mineralogy

what are the 3 main mechanisms that have driven mineral diversity

1) separation and concentration of elements from original relatively uniform distribution in the presolar nebula

2) increase in range of combinations of intensive variables such as temperature, pressure, and activities of H2O, CO2, and O2

3) far-from equilibrium conditions that produce thermodynamically metastable minerals

what happens in stage 1

primary chondrite minerals

Ni-Fe metals, sulfides, phosphides, silicates, oxides

what happens in stage 2

olivine crystals in an iron-nickel matrix

alteration of primary chondrite minerals

what are some components of crust and mantle re-working

metamorphism, planetary “water pump,” mountain building, mid-ocean ridges, subduction zones, deep crust

what are the oldest minerals? from where? how old?

zirons, Jack Hills, Australia, 3.3 billion years

oxygen isotopes suggest the zircons came from what

granite

what is Bowen’s reaction series

description of how the minerals crystallizing from a magma change as temperature decreasesand how this affects the composition of igneous rocks.

what is adiabatic decompression

depressurization without exchange of heat with the surroundings

what happens in melt segregation

unmelted minerals get compacted and expel the melt upward

what is the 4 step process to form granites and pegmatites

1) melt mantle

2) make a basalt

3) make a granite

4) make pregmatite

“black smokers” are chimneys formed from deposits of

iron sulfide

“white smokers” are chimneys formed from deposits of

barium, calcium, and silicon

the era of biologically-mediated mineralogy was prompted by this event and created this

great oxidation event

banded iron formation

what is the red and gray colors in BIFs

red is oxidized hematite, gray is reduced magnetite

what happened during era 3

intermediate ocean, snowball earth, and phanerozoic era of biomineralization

what are 3 examples of man-made minerals in the anthropogenic era

acid mine drainage, toxic spills, radioactive waste

what are the 3 major divisions of Earth’s structure

crust, mantle core

the mantle is mainly this mineral which is composed of 4 minerals

peridotite

olivine, clinopyroxene, orthopyroxene, and aluminum mineral

what are the aluminum minerals from low to high depth

plagioclase, spinel, garnet, Si to VI coordinated SiO6

what does the An-Fo binary look like

what is the composition of the first magma to form from the melting of the mantle

point “M” (basalt), eutectic point

naming of mafic (basalt-like) rocks are assigned based on these 2

1) relative amounts of different minerals (coarse grained)

2) chemical composition (fine grained)

what are the relative amounts of minerals present in plutonic rocks

what are the light and dark minerals in intermediate igneous rocks

light: plagioclase and/or quartz

dark: amphibole and/or biotite

which is more felsic, granodiorite or diorite

granodiorite

what are the 2 ways fractional crystallization can happen

physical separation of crystals from magma

chemical zoning of crystals

igneous processes result in a differentiated crust. lighter minerals on top, heavier below. name 2 light and 2 heavy minerals

light: granite and pegmatite

heavy: gabbro, peridotite

lithium is found in what mineral

illite, which was altered from clay minerals by hydrothermal fluids