Exam 1 Review

Prep for Exam #1 - origin of the universe, types of minerals, and type of rocks.

big bang theory

massive explosion occurring 15 bya from singularity

marks beginning of the universe

singularity

incredibly dense, energetic, yet very small concentration in space

part of the big bang

The big bang theory describes…

the origin of the universe

matter, right after the big bang

very hot

has cooled down as time went on

evidence of the big bang

red shift / Doppler effect

background microwave radiation

red shift / Doppler effect

fast moving objects going away from us elongates light waves, “shifting” objects to become closer to the lower frequency red range

nebular theory

planets were formed from nebular clouds

contraction began \~ 5 bya

produced gravitational collapse of the nebular, causing heat, molten rock, and “dirty orbits” that haven’t defined themselves yet

nebula

cloud of gas and space dust

The nebular theory describes…

the origin of the solar system

inner planet traits

none or few moons

smaller

rocky

denser

hotter

outer planet traits

many moons

larger

gaseous

less dense

colder

Earth’s place in the solar system

part of the inner planets

Proto-Earth characteristics

larger in size than today’s Earth

Had lots of volcanic activity

HOT

no continents or oceans

no life

still clearing its orbit

density stratification

creation of layers from lower density material rising above the sinking, higher density material

layered Earth was formed by…

density stratification

layers of Earth (internally)

inner core (solid iron)

outer core (liquid iron)

mantle

crust

proto-Earth’s atmosphere

hydrogen

helium

source of proto-Earth’s atmosphere

density stratification

What happened to proto-Earth’s atmosphere?

burnt off immediately because it was still so hot

early Earth’s atmosphere 5 bya

***water vapor***

***nitrogen***

***carbon dioxide***

carbon monoxide

ammonia

methane

sulfur dioxide

NO FREE OXYGEN

source of early Earth atmosphere

volcanic out-gassing

present day Earth atmosphere

\~3/4 nitrogen

\~1/4 oxygen

source of present day Earth atmosphere

volcanic out-gasing

photosynthesis

origin of free oxygen gas in present day atmosphere

life evolving \~3.8 bya performing photosynthesis

Earth’s spheres

atmosphere

hydrosphere

cryosphere

biosphere

geosphere/lithosphere

atmosphere

thin gaseous envelope surrounding Earth

hydrosphere

water layer dominated by the oceans

source of hydrosphere (oceans)

H2O vapor and other gases condensed into clouds when planet began to cool down, raining down into the ocean

cryosphere

ice layer, including ice caps and glaciers

biosphere

all life on earth

The biosphere mostly resides…

just above or at sea level

geosphere/lithosphere

earth’s rocky surface, that is layered internally

internal sources of energy for Earth

radioactive decay (potassium, uranium, thorium)

decay releases heat energy

external sources of energy for Earth

driven by the light energy of the sun

absorbed by atmosphere, oceans, and continents → converted to heat

drives circulation, head transfer, evaporation, and condensation

mineral

natural, inorganic crystalline solid that have exact chemical composition with an orderly internal arrangement of atoms (has a structure)

formed generally by inorganic processes

ionic bonds

formed by force from ions of opposite charges

usually formed by elements far apart on the periodic table

covalent bonds

sharing of electrons to get noble gas structure

metallic bonds

electrons move freely from atom to atom, being constantly shared

weak bond form, but conduct electricity well because of the free electron movement

chemical bonds, ranked from strongest to weakest

covalent

ionic

metallic

states of matter

solid

liquid

gas

types of solid matter

crystalline

amorphus

crystalline solid

atoms bond together in a regular, orderly pattern

amorphous solid

atoms bonded together in a random pattern

liquid

atoms or molecules tightly packed, but allowed to slip past each other in random motion

gas

particles in random motion at high speeds, separated by empty space

\n The orderly internal arrangement of atoms in a mineral \n causes it to…

exhibit characteristic physical properties that allow the mineral to be identified

polymorph

minerals with the same chemical composition, but different internal structure

example of a polymorph mineral

diamond and graphite

both made of carbon, however, graphite is made in a 3D formation, while graphite is made of sheets.

________________ may occur, causing small variations in composition

ionic subsitution

ionic subsitution

the replacement of ions with similar charges in a formula

ex. biotite - K*(Mg,Fe)*3AlSi3O10(OH)2

native element

type of mineral, only composing of one element

ex. gold - Au

physical properties of minerals

crystal form/habit

color

streak

luster

cleavage

density

hardness

crystal form/habit

shape in which individual crystals or aggregates grow

streak

color of powdered mineral

usually shown on an unglazed porcelain tile

luster

how the mineral looks with the reflection of light

types of luster

metallic

nonmetallic

vitreous

pearly

resinous

greasy

cleavage

planes along which the mineral breaks easily

hardness

how easily a mineral can scratch (or be scratched) by another mineral

If no space and time restrictions are present, crystals will…

be well developed (their ideal form)

The size of the atoms determines the…

architecture of the crystal structure.

If space and/or time restrictions are present, crystals will…

not be grown in their ideal form

will grow to completely fill their space

cleavage types

1 direction

2 directions at 90 degrees

2 directions NOT at 90 degrees

3 dimensions at 90 degrees

3 dimension NOT at 90 degrees

fracture / no cleavage

1 directional cleavage

sheds off in sheets due to weak bonds holding together strong silicate sheets

ex. Micas

2 dimension at 90 degrees cleavage

break off in 2 dimensions (but not in a cube - has a rounded dimension), forming 90 degree corners

ex. feldspars and pyroxene

2 dimension NOT at 90 degrees cleavage

break off in 2 dimensions (but not in a cube - has a rounded dimension), forming 60/120 degree angles (or other angles not at 90 degrees)

ex. amphiboles (hornblende)

3 dimension at 90 degrees cleavage

cube-like shapes at 90 degrees

ex. halite

3 dimension NOT at 90 degrees cleavage

rhombohedral-shape, forming 60/120 degrees (or other degrees instead of 90)

ex. calcite

fracture

no cleavage

break off into shards

ex. quartz, obsidian

What is the cause of fracturing minerals?

have equally strong bonds in all directions, cannot find regular path of breaking

Is cleavage different than crystal form?

Yes, it is.

Crystal form is the ideal growth given no space or time restrictions,

and cleavage is the result of breaking with the same geometry (or lack of, if it fractures)

Moh’s hardness scale

arbitrary, exponential scale to compare hardness from 1 (talc) to 10 (diamond)

hardness scale tests

2\.5 - fingernail

3\.5 - copper coin

4\.5 - paper clip

5\.5 - Knife blade, glass plate

7\.5 - steel file

Four unknown minerals labeled A, B, C, and D are needing to be tested for hardness. You do not have a hardness testing kit, and you just cut your nails, so you decide to test the hardness of each mineral relative to each other. After some tests, you conclude the following:

Mineral A can scratch Mineral B.

Mineral A cannot scratch Mineral C.

Mineral B can scratch Mineral D.

Mineral D cannot scratch Mineral A, B, or C.

Rate the hardness of the minerals from softest (closest to 1) to hardest (closest to 10).

D, B, A, C

special physical properties for specific minerals

taste (halite)

striations (plagioclase feldspars)

magnetism (magnetite)

double refraction (calcite)

chemical tests (limestone)

___________ is not the best characteristic to ID minerals because…

color

has a great deal of variation for a lot of minerals

ex. rose quartz, smoky quartz, etc.

In a streak test, if the mineral is harder than the porcelain…

it leaves no streak and scratches it instead

most common elements in crustal rocks by abundance

oxygen

silicon

aluminum

iron

calcium

sodium

potassium

magnesium

silicate minerals

most common minerals on earth

make up 95% of crust volume, and 75% of all of Earth’s mass

based on the silica tetrahedron - SiO4^-4

2 ways silica tetrahedra balance charges

attaching to metals, which usually have + charges

sharing oxygen atoms, which reduces charge on each tetrahedron

or a combination of both

types of silicate linkages

single tetrahedron

single chains

double chains

2D sheets

3D frameworks

single tetrahedrons silicates

isolated tetrahedra

need to be bonded with cations

single tetrahedrons silicates example

olivines

single chain tetrahedra silicates

share a single oxygen atom to reduce overall negative charge - as a result, reduce the need for cations between each tetrahedra

cations hold the chains together

single chain tetrahedra silicates examples

pyroxene group, like augite

combines with iron and/or magnesium

double chain tetrahedra silicates

two parallel chains

every other tetrahedron along the chain shares one oxygen atom with an adjacent chain

like single chains, reduces the overall negative charge and need for cations further

double chain tetrahedra silicates examples

amphiboles group, like hornblende

combines with iron and/or magnesium

sheet tetrahedra silicates

each tetrahedron shares 3 oxygen atoms, forming a sheet

cations hold the sheets together

sheet tetrahedra silicates examples

mica group, including clays, biotite, muscovite

can be seen combined with iron and/or magnesium (biotite)

or aluminum and/or potassium (muscovite)

framework silicates

all 4 oxygen atoms shared by adjacent tetrahedrons

framework silicates examples

quartz and feldspars

ratio of silica to oxygen in silicate linkages

less Si: more O in simpler linkages, like isolated tetrahedrons

more Si: less O in complex linkages, like framework

density in silicate linkages

most dense in simpler linkages, like isolated tetrahedrons

least dense in complex linkages, like framework

types of minerals based on chemical composition

carbonates

oxides

native elements

sulfides

sulfates

silicates

carbonates

minerals with CO3^-2

ex. calcite (CaCO3)

oxides

being composed of oxygen (O^-2)anions and metallic cations

rusts

ex. hematite (Fe2O3)

sulfides

minerals that have sulfide anions (S^-2) and metallic cations

ex. pyrite

sulfates

minerals that have sulfate (SO4^-2) anions and metallic cations

ex. gypsum, anhydrite

types of silicates based on silica content

felsic/silcic

intermediate

mafic

ultramafic

felsic/silicic silicate minerals

high Si (>75-65%)

has Al or other metals other than Fe or Mg

relatively low crystallization temperatures

less dense

major minerals - mostly light in color

intermediate composition

intermediate Si (55-65%)

equal parts mafic and silicic

ex. andesite