ESC1000 Midterm

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ions

an atom or molecule with a net electric charge due to the loss or gain of one or more electrons

compressional differential stress

shortens a rock body

element

a substance that cannot be broken down by chemical means

rock strength

amount of stress a material can endure before it strains

mole

6.02 x 10^23

synthetic diamonds

>80% of diamonds produced are synthetic

rock types reveal

info about past environments, especially when compared to modern systems

you can find larger river systems near

larger mountain belts

mud (clastic sedimentary)

mudstone & shale

anions

negatively charged ions

atmosphere contains mostly elements

nitrogen & oxygen

unloading

occurs when overlying material, such as soil or another rock stratum, is removed (most commonly through erosion) and confining pressure on the underlying rock is decreased. In response, the rock generally fractures into sheets which lie perpendicular to the direction in which pressure is released.

cementation

precipitation of dissolved ions in pore space "gluing" minerals

mud cracks

preserved in rock tell us that the area was very wet at certain times ex: floodplain or tidal flat

Blue diamonds

Diamond, B

Schrodinger model

Quantum mechanics

cations

positively charged ions

color of diamond

-colorless: no impurity, pure Carbon -yellow: Nitrogen -blue: Boron

internal structure of minerals

"How it's put together" -As a function of bond type & strength, structure affects hardness -Geometry of structure affects mineral form

composition of minerals

"What's in it" this can affect color and bond strength

atomic #

# of protons

strain in deformation

-"changes" in the shape due to stress -"results" -rocks exhibit strain brought by the forces of stress ex: faulting, folding, & flowing

brittle deformation (fracture)

-after stress is removed, rock does not return to its original shape -permanent & irreversible -loses structural continuation

ductile deformation

-after stress is removed, the rock does not return to its original shape -permanent & irreversible -plastic deformation -structural continuation inside

elastic deformation

-after stress is removed, the rock returns to its original shape -nonpermanent, reversible

magma intrusion

-alters the local geothermal gradient -raising temperature -metamorphoses adjacent rock

gems prized for

-beauty (color, transparency, durability) -durability (hardness, resistance to abrasion)

fossils

-biologic remains in sedimentary rock -used to interpret ancient environments from their buried remains -ions in pore water may replace original cellular matter, usually quartz, calcite, or hematite

low-grade metamorphism

-burial to 12km -temp about 240 C

buying a diamond (C's)

-carat -color -clarity -cut -cost

partial melting

-causes wide variation in chemical composition -each mineral has different melting temperature -each element has different tendency to move into melt

clastic sediment

-composed mainly of mineral grains weathered from pre-existing rock & cemented together by precipitated minerals -texture

marble

-composed of calcite -white -from limestone

chemical/biogenic sediment

-composed of minerals precipitated from water by biologic or inorganic processes, or the remains of organisms -composition

mafic rock

-dark-colored igneous rock containing minerals such as pyroxenrs & olivinez that are rich in iron & magnesium while relatively poor in silica -form in the seafloor MAgnesium-FerrIC

sedimentation

-deposition of sediments -after being carried away by water, wind, or ice, sediments are deposited -typically in formations called beds or layers -usually horizontal

Thomson & Rutherford

-discovered electron (1897) -plum-pudding model (1904) -discovery of nucleus from scattering experiment (1911) -nature of nucleus --> field of nuclear physics

Bohr model

-discrete energy levels in electronic structure -shell model (1913)

temperature in metamorphism

-drives away water & gases -enhance diffusion of elements/ions -induces chemical reactions -different minerals are stable in different physical conditions (ex: water, ice, vapor vs diamond & graphite)

effusive volcanism

-erupted lava typically liquid -dissolved gas comes out quickly as pressure decreases -low viscosity

rhyolite

-felsic -igneous -extrusive

granite

-felsic -igneous -intrusive

bioturbation structure

-footprint of animals on bedding surface -can tell us which side is up

sedimentary rocks

-formed by deposition and precipitation of materials coming from the breakdown of older rocks -soft (less resistant to erosion) -weathering breaks down & dissolves parts of a rock (clastic sediment / dissolved ions)

sand (clastic sedimentary)

-grain size: 1/12-2mm rock name: sandstone -quartz sandstone (95% quartz grains) -Arkose (25% feldspar w/ quartz) -lithic (90% quartz & more rock fragments than feldspar)

gravel (clastic sedimentary)

-grain size: larger than 2mm -rock name: -breccia (if fragments are angular) -conglomerate (if if fragments are rounded)

physical properties of diamonds

-hardest natural substance -high dispersion (white light into rainbow colors) -high luster

gneiss

-high metamorphic -from schist or granite -foliated

foliation

-how rock texture record strain -role of pressure in metamorphism

four sources of natural diamonds

-impact sites (very rare, nanodiamonds) -meteorites (very rare, nanodiamonds) -deeply-buried crust @ low geothermal gradients (rare, microdiamonds) -mantle-derived kimberlites (abundant, most jewelry or industrial diamonds)

how to melt a rock

-increase temperature -lower confining pressure -add water

schist

-intermediate metamorphic -from phyllite -foliated

phyllite

-intermediate metamorphic -from slate -foliated

diamond uses

-jewelry -abrasives, drill bits, saw, semiconductors -high pressure apparatus

crystallization

-key process in mineral formation -process of formation of solid crystals from a uniform solution -minerals grow outward from a central seed to fill the available space; their shape is controlled by the shape of their surroundings

batholith

-largest kind of intrusive igneous body -major batholith in the West Coast -felsic or intermediate rock types

felsic rock

-light-colored igneous rock that is poor in iron and magnesium while rich in high-silica minerals (quartz, orthoclase feldspar, & plagioclase feldspar) -form in continental plates FELdspar-SIliCa

slate

-low metamorphic -from shale or mudstone -foliated

Magma formation processes in Earth

-lowering confining pressure (decompression melting: Mid-Ocean Ridge) -adding water (Hydration melting: Subduction zone) -Increasing temperature (Temperature-Induced Melting)

basalt

-mafic -igneous -extrusive -from volcanoes

gabbro

-mafic -igneous -intrusive

stress deformation

-magnitude of force per unit area -"cause"

oceanic crust

-mainly composed of basalt -phynocryst: A few visible large crystals which crystallized in magma and brought onto surface with magma

factors controlling weathering rates

-mineralogy -rock type & structure -slope angle -climate -presence/absence of soil -time -water -temperature

Mineral

-naturally occurring -inorganic solid -ordered internal molecular structure -definite chemical composition ex: quartz, biotite, plagioclase

diamonds

-nearly pure elemental carbon -high pressure form

Weathering & Sedimentation

-occurs at sea level around subduction zone

Metamorphism

-occurs in lithosphere of subduction zone

fossil fuels

-organic matter buried w/ sediment changes under increased temperature over time to combustible organic compounds such as coal, oil, & natural gas -stored chemical energy from the sun -energy can be released by oxidation (burning)

main components of metamorphism

-original rock material -temperature -pressure -fluid (abundance & composition) ---> by burial, intrusion, structural mvts, etc

elements

-over 116 known, 92 naturally occur -defined by # of protons

sediments

-particles of rocks, minerals, or organic matter that are transported by water, wind, or ice ex: sand, mud, silt

chemical weathering

-reaction of rocks w/ water or atmosphere -easily dissolved minerals (ex: halite & calcite) react the fastest -leads to retention of very stable minerals (like quartz) and rounding of mineral grains

quartize

-recrystallization of pure quartz sandstone by metamorphosis -light colored -medium to coarse grained -sometimes foliated

igneous rocks

-rock formed by the solidification of magma -hard (more resistant to erosion)

Rock

-solid aggregate of minerals (+/- non-minerals such as volcanic glass or organic matter) ex: basalt, granite, limestone

limestone

-sources of calcite: marine organism (shell + skeleton) & dissolved CaCO3 -forms in warm area in shallow ocean -10% by volume of total sedimentary rocks -very important sink of atm CO2 -soluble -generate landforms w/ pavements, sinkholes, caves -popular in architecture (heavy & $$$)

uniform stress

-stress equal in all directions -changes volume, but not shape ex: burial

differential stress

-stress strongest in one direction -changes shape -more common

measure of strain

1. length change 2. volume change

factors that influence deformation

-temperature -confining pressure -rock type (composition) -rate of deformation

depositional environments

-the characteristics used to name sedimentary rocks also can be used to interpret the history of an area ex: sea floors, beaches, stream beds, swamps (all have diff. sedimentary characteristics)

magmatism

-the motion or activity of magma -occurs at Mid-Ocean Ridge, Volcanic Arc, & Hot Spots

lava flow distance

-viscosity (low -> extended flow) -melting temp (low -> extended flow) -eruption rate (high -> extended flow)

how does magma form?

1. Lower confining pressure 2. Add water 3. Increase temperature

role of fluid in metamorphism

1. react w/ minerals to form new minerals that contain components of the fluid molecules -OR- 2. change the metamorphic rock by delivering & removing dissolved ions, fluid makes reactions occur faster & more easily

as grains travel from the source

1. roundness increases 2. size decreases 3. sorting increases

cleavage

1. the tendency of a crystal to break along planar surfaces 2. the geometric pattern produced by such breakage

lava tube

A natural conduit through which lava travels beneath the surface of a lava flow, expelled by a volcano during an eruption. They can be actively draining lava from a source, or can be extinct, meaning the lava flow has ceased and the rock has cooled and left a long, cave-like channel

Emeralds

Beryl, Cr

Aquamarines

Beryl, Fe

Sapphires

Corundum, all colors besides red

Rubies

Corundum, red color, Cr

metamorphism

Describes the mineralogical, chemical, and textural changes to preexisting rocks that occur in a (more or less) solid state due to increased temperature & pressure

Yellow diamonds

Diamond, N

relatively high abundance of elements

Fe, Ni, Pb

biological activity

Growing plant roots can exert stress or pressure on rock. Although the process is physical, the pressure is exerted by a biological process

wet/hydration melting

H20 in the form of steam dissolving into rock which causes the rock to melt at a lower temperature

most abundant elements

Hydrogen & Helium (more than 99% of all atoms)

relatively low abundance of elements

Li, Be, B, Sc

hardness scale

Mohs Scale of Hardness 10 Diamond 9 Corundum 8 Topaz 7 Quartz most gems are 7 or higher

covalent chemical bond

atoms share outer electrons

most abundant mineral in Earth's crust

Silicate (Si-O chain)

hardness

a measure of the ease with which the surface of a mineral can be scratched

gemstone

a mineral, rock, or petrified material that when cut or faceted and polished is collectible or can be used in jewelry

frost wedging

a physical weathering process in which the expansion of freezing water in cracks in rock breaks the rock

color & streak

a property of a mineral imparted by transmitter or reflected light

explosive volcanism

a volcanic term to describe a violent, explosive type of eruption

intermediate igneous rock

an igneous rock midway in composition between mafic and felsic, neither as rich in silica as felsic rock nor as poor in it as mafic rock

dunes & ripples

are both formed by the direction of forces (winds & currents) to which they are subjected

crystal growth

as water percolates through fractures and pore spaces it may contain ions that precipitate to form crystals. As these crystals grow they may exert an outward force that can expand or weaken rocks

isotopes

atoms of the same element with different numbers of neutrons

most abundant extrusive rock

basalt (mafic)

classification of igneous rock

based on: -texture (ex: grain size) -chemical composition (ex: SiO2 content)

colors in gemstones/minerals

caused by: -defects in crystal structure -intrinsic chemical constituents -chemical impurities

shear differential stress

causes rocks to slide past each other

deformation

changes in location, orientation, shape, &/or size of a rock body

seawater is full of elements of

chloride & sodium

pyroclastic flow

cloud of debris is very fast, very hot, & contains huge blocks (most devastating)

intrusive igneous rock

coarse-grained igneous rock formed from magma that intrudes into country rock deep in Earth's crust and cools slowly (large crystals)

chemical sedimentary rocks

comp: --- rock name: calcite --- limestone dolomite --- dolostone quartz --- chert

tectonic uplift rate

controls erosion rate & vice versa

lithification

conversion of sediments into rock via compaction & cementation

compaction

decrease in volume due to loss of pore space

metallic chemical bond

electrons move from atom to atom, inner electrons shared

Van der Waals chemical bond

electrostatic forces causing dipole movement (microscopic separation of positive and negative charge centers)

tensional differential stress

elongates a rock body

atomic mass

equal to average number of protons plus neutrons

Karst

erosion landscaping made of limestone

extrusive igneous rock

fine-grained or glassy igneous rock formed from magma that erupts at Earth's surface as lava cools rapidly (tiny crystals)

most abundant intrusive rock

granite (felsic)

Isostasy

gravitational equilibrium between lithosphere (rigid material) and asthenosphere (fluid)

Z elements

greater abundance of even Z elements compared to odd Z elements

clarity

how clear a diamond is (free from inclusions and blemishes) - FL-flawless - IF-internally flawless - VVS1 and VVS2-very very slightly included - VS1 and VS2-very slightly included - SI1 and SI2-slightly included - I-imperfect (visible with naked eye)

continental crust

mixture of intrusive and extrusive igneous rocks (+ metamorphic and sedimentary rocks)

polymorphs

one of 2+ alternative possible crystal structures for a single chemical compound ex: the minerals quartz and cristobalite are polymorphs of silica

ionic chemical bond

oppositely charged ions attract

important minerals

ore minerals & gems

most minerals made of the elements

oxygen & silicon

fossils used to interpret

past environments (climate & vegetation)

physical weathering

processes that break rock into smaller fragments

chemical weathering

processes that dissolve some minerals (causing dissolved ions to be carried away) and to create new minerals

recrystallization of minerals into new sizes & shapes

sandstone (sedimentary rock) -> quartize (metamorphic rock) limestone (sedimentary rock) -> marble (metamorphic rock)

dike

sheet of rock that formed in a crack in a pre-existing rock body

compound

substance formed by two or more elements chemically bonded together

thermal expansion

sudden exposure to high temperature may cause expansion and eventual breakage of rock ex: wildfire

minerals used "as found"

sulfur, silver, gold, diamond

sill

tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock.

geothermal gradient

temperature increases w/ depth into Earth

atom

the basic unit of a chemical element, smallest particle that retains distinctive properties of an element

density

the mass per unit volume of a substance ex: g/cm^3

weathering

the physical or chemical breakdown of rocks at Earth's surface

erosion

the physical removal of material by water, wind, ice, or gravity (transport)

crystal form & growth habit

the shape in which a mineral's individual crystals or aggregates of crystals grow

decompression melting

the spontaneous melting of rising mantle material as it reaches a level where pressure decreases below a critical point, without the introduction of any additional heat

luster

the way the surface of a mineral reflects light

streak

thin layer of powdered mineral made by rubbing the specimen on the place

how do we determine mineral stability?

using a cylindrical pressure chamber

kimberlites

volcanic pipe, explosive volcanic eruptions from deep in the earth that bring already formed diamonds to surface

rock cycle

weathering-erosion-deposition-lithification-metamorphism-melting-crystalization-uplift-weathering

reverse faulting

when one block of crust is forced over another, the lower one heats to a temperature associated with its depth

thin section

when you cut and glue rocks and minerals on a glass slide and sand it

approximate # of known minerals

~4,000


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