geology rox

talc 1, gypsum 2, calcite 3, fluorite 4, apatite 5, orthoclase 6, quartz 7, topaz 8, corundum 9, diamond 10

mohs’ hardness scale

quartz

silicate, hardness of 7, concrete

potassium feldspar

silicate, 2 planes of 90° cleavage, salmon pink, lowers the melting temperature in glassmaking and ceramics

plagioclase feldspar

silicate, 2 planes of 90° cleavage, white or gray, lowers the melting temperature in glassmaking and ceramics

hornblende

amphibole, oblique cleavage angles of 56° and 124°, abrasive

augite

pyroxene, grayish streak, no industrial use but used in geological research

olivine

silicate, hardness of 6.5, abrasive

muscovite

silicate, hardness of 2.5, heat and electrical insulator

biotite

silicate, perfect basal cleavage, filler in paint and rubber

garnet

silicate, no cleavage, sandblasting

talc

silicate, hardness of 1, baby powder and cosmetics

kaolinite

silicate, dull luster, paper production

calcite

carbonate, dissolves in HCl, cements and mortars

dolomite

carbonate, dissolves in HCl, extraction of magnesium

halite

chloride, tastes salty, cooking

fluorite

fluoride, hardness of 4, source of fluoride for teeth

magnetite

oxide, magnetic, steel production

hematite

oxide, metallic or dull luster, iron and steel production

gypsum

sulfate, hardness of 2, plaster

barite

sulfate, vitreous and pearly luster, drilling mud for petroleum

pyrite

sulfide, metallic luster, fools gold

galena

sulfide, metallic luster, lead-acid batteries

sphalerite

sulfide, 1 perfect plane of cleavage, zinc ore

graphite

native element, gray streak, pencil lead

sulfur

native elements, smells like rotten eggs, fertilizer production

metallurgy

the process of extracting elements from rock

element

a substance made up entirely of one type of atom with the same atomic number (number of protons)

mineral

naturally-occurring chemical compound, composed of one or more elements

rock

solid aggregate of one or more minerals

mineral requirements

1. naturally-occurring

2. inorganic

3. solid

4. definite chemical composition

5. ordered atomic arrangement

THIS IS WHY ICE IS A MINERAL 🧊

atomic number

number of protons in the nucleus of an atom. determines the chemical properties of an element and its place in the periodic table

ion

an atom with an unequal number of protons and neutrons, creating a positive (cation) or negative (anion) charge

isotopes

atoms of the same element with different numbers of neutrons

hubble

proved that:

1. the universe goes beyond the milky way

2. the universe is expanding (doppler effect)

big bang theory

the universe was created 13.8 Ga when all of its mass and space were concentrated in a single particle. this particle exploded, creating a fireball, which cooled as it expanded

H and He

elements in early universe

star

formed by the contraction of H and He under the influence of gravity. when the core temperature gets hot enough, the H-fusion reaction starts

H fusion

dominant process that generates energy in the cores of main-sequence stars. H protons fuse to form ⁴H nucleus. by adding alpha particles and capturing neutrinos, we can build the rest of the periodic table

red giant

when most of the H has been converted, the rate of energy production initially decreases, and the star contracts. the compression of the interior raises the temperature around the core, and the site of fusion shifts to the shell outside the core

alpha particle

two protons and two neutrons bound together into one particle, identical to an He nucleus

triple alpha process

two ⁴He atoms collide to form a nucleus of ⁸Be. problem: ⁸Be is unstable, but ⁹Be is stable. solution: to become stable, it must assimilate a third alpha particle immediately

⁸Be + ⁴He → ¹²C + energy

neutron capture

an atom captures additional neutrons and becomes an unstable isotope, so it must decay by emitting an electron

⁵⁹Fe → ⁵⁹Co + beta particle + neutrino + energy

supernova

when a star reaches the end of the red giant stage, it explodes

nebula

the gas ejected by a supernova into space forms a molecular cloud. our sun and its planets likely formed from the contraction of a molecular cloud

protostar

contracting mass of gas that represents an early stage in the formation of a star. emits energy by light and infrared rays but not yet by nuclear reactions

protoplanetary disc

contraction of the solar nebula increases its rate of rotation. the irregular cloud is flattened into a disc, which extends out from the protosun at the center. the local composition is related to the temperature/distance from the protosun

planetesimals

during the final stages of the contraction of the sun, the solar wind blew most of the volatiles out of the protoplanetary disc, leaving refractory dust particles that could stick together and grow in mass to form planets. those in the inner part of the disc are mainly composed of refractory particles, while those in the outer part are composed of dust AND ice

4.56 Ga

age of the solar system

4.54 Ga

age of earth

iron

earth’s core

sulfides

earth’s mantle

silicates

earth’s crust

goldschmidt classification

distribution of elements in today’s earth reflects their siderophile, chalcophile, lithophile, and atmophile behavior

siderophile

• iron-loving

• metallic liquid phase

• core

• typically also chalcophile

chalcophile

• sulfur-loving

• sulfide liquid phase

• may be concentrated in core

• typically also siderophile

atmophile

• gas-loving

• extremely volatile (form liquids and gases at earth’s surface)

• atmosphere and hydrosphere

lithophile

• rock-loving

• silicate phases

• concentrated in silicate portion of earth (mantle and crust)

silicate differentiation

when earth cooled, silicate minerals crystallized from the silicate magma forming the mantle and crust. the sequence of silicate minerals that crystallize from cooling magma depend on:

• temperature

• pressure

• magma composition

bowen’s reaction series

olivine and pyroxene

denser, found in mantle and oceanic crust

quartz and feldspar

less dense, found in continental crust

magnetic field

created by convection currents in the outer liquid core

mantle

layer above the core. mainly solid but behaves like a viscous fluid in geologic time

hadean

• 4.6-4.0 Ga

• toxic atmosphere

• magma ocean

• early asteroid bombardment

• basically hell

archean

• 3.8-2.5 Ga

• gases from volcanism and asteroid impacts formed second atmosphere, better but still toxic

• allowed for early life

• bombardment slowed down

• earth cooled

• “the beginning”

the great oxidation event

• 2.4 Ga

• free oxygen started to exist in the atmosphere

proterozoic

• 2.5-0.5 Ga

• eon before complex life

• “earlier life”

phanerozoic

• 0.5 Ga-present

• rapid evolution of life

• “visible life”

evaporites

water-soluble mineral sediments left behind when evaporation occurs

definite chemical composition

all minerals have specific ratios of cations to anions

native elements

elements that occur in nature in uncombined form with a distinct mineral structure

alloys

mixture of two elements, one of which is a metal

hardness

resistance of mineral surface to scratching

streak

color of powdered mineral

luster

overall sheen or look of surface

habit

how crystals tend to form when unobstructed

cleavage

the way a mineral breaks along preferred atomic planes

igneous

rocks formed by crystallization and cooling of magma on or near earth’s surface. the type of rock formed depends on:

• cooling rate

• pressure

• magma composition

felsic

• feldspar - silica

• magma rich in quartz and feldspar

• light-colored

mafic

• magnesium - Fe

• magma rich in olivine and pyroxene

• dark-colored

plutonic

• intrusive

• slow-cooling

• larger crystals

• granite

volcanic

• extrusive

• fast-cooling

• small to no crystals

• basalt

viscosity

the property of a liquid to resist flow when a shear stress is applied (ex. how fast ketchup pours when you tip the bottle over). the higher the SiO₂ content, the higher the viscosity

subduction zone

denser slab of oceanic crust goes below less dense slab of continental crust. SiO₂-rich magmas migrate upwards and erupt violently

hot spot

mantle plumes low in SiO₂ rise from deep in the earth. they pierce the crust and erupt quietly. as plates move above them, they create volcano island chains (hawaii)

mid ocean ridge

mantle magmas are erupted along divergent plate boundaries

sedimentary rock

sediment particles that are lithified into cohesive rock mass. can tell a lot about paleo-environmental conditions

compaction

increased pressure due to burial/loading

cementation

mineral phases that precipitate from water and volcanic ash

ripples

bedforms created at low velocities

sand dunes

bedforms created at increased velocities

plane beds

bedforms created at great velocities

antidunes

bedforms created at greatest velocities

cross bedding

layering in one or multiple beds that is at an angle to the plane of stratification. formed when sand eroded from the windward side of the dune is deposited on the other side. generally sand dunes, can be ripples

clastic/detrital

sedimentary rocks derived from weathering/erosion of pre-existing rocks

chemical

sedimentary rocks formed from chemical precipitation (ex. limestone, carbonates, evaporites)

conglomerate

clastic sedimentary lithology with poorly sorted, rounded clasts. transported in a high-energy environment, typically rivers or glaciers. how we knew there were rivers on mars!

breccia

clastic sedimentary lithology with angular clasts in a finer matrix, suggesting limited transportation. typically seen on steep hillsides or foots of cliffs

sandstone

clastic sedimentary lithology with sand-sized fragments, mostly quartz and feldspar. formed in moderate-energy terrestrial or marine environments. described in terms of cementation, sorting, and grain size (within range)

mudstone

clastic sedimentary lithology with fine grain, original constituents clays and muds. low energy depositional environment like an estuary or lagoon. important rock source for petroleum