-
Each mineral has a...
and...
Definite chemical composition; internal atomic structure
-
Sodium Chloride (NaCl)
Halite, tastes like salt
-
-
Why study minerals?
- fundamental building block of rocky planet
- rock = mixture of minerals
- form under physical & chemical conditions
- help us understand earth processes
- most metals originate from minerals
- manufacturing
- biological processes from minerals as well
-
seashells & pearls=
bones & teeth=
- calcium carbonate
- phosphate minerals
-
most abundant element (universe, sun, humans)
hydrogen
-
earth's comp
oxygen - 50, iron -17, silicon/magnesium - 14
-
earth's crust comp
oxygen- 47, silicon- 28
-
earth's atmosphere comp
nitrogen -78, oxygen - 21
-
-
lead has high or low density
high density mineral contains...
-
Lead sulfide (PbS)
Galena, heavy shiney silver metallic
-
What is Mohs?
Hardness scale, with log scale of absolute hardness on y axis
-
List the 9 Mohs's hardness scale minerals
- Diamond.Corundum.Topaz.Quartz.
- Feldspar.Apatite.Florite.Calcite.Gypsum.Talc
-
colors vary depending on...
impurities
-
Name cleavage of each mineral:
Mica. Florite. Calcite. Quartz
single.double.rhombihedral.none
-
Titanium makes quartz...
Iron makes quartz...
-
Type of bond is determined by...
....the arrangement of electrons around the nuclei of the atoms involved
-
ionic bond...
electrons transfered.weaker than covalent bonds. ex NaCl
-
covalent bond....
eletrons shared. strongest bond. ex: carbon or water
-
metallic bond...
electrons roam between atoms. makes them conductive and shiney
-
van der waals bond....
unequal electron distribution around nuclei creates weak charge assymentry. ex "soft" minerals like talc
-
two minerals that have both ionic and covalent bonds
- Calcite (CaCO3)
- Quartz (SiO3)
-
the lopsided geometry of water gives it......which allows it to pull apart weakly bonded minerals
polarity
-
a mineral is....
- naturally occuring solid
- usually inorganic
- defined chemical composition
- an ordered atomic structure
-
a mineral isn't....
- man-made (cubic zirconia or synthetic ruby)
- liquid or gas
- organic compounds (like table sugar or coal)
- amorphis or non-crystalline (obsidian, glass is amorphis and technically a very slow-flowing liquid)
-
types of atoms =
composition
-
composition determines...
- bond strength
- atomic structure
-
controlled by atomic structure (how mobile electrons are within the crystal to affect smoothness; reflect atomic arrangement of atoms)
luster & crystal form
-
contolled by comp
density & color
-
controlled by bond strength
- hardness (and atomic structure)
- cleavage
-
controlled by hardness
streak
-
diamond versus carbon
various colors, transparent, hardness 10, 3D network of C atoms, electrical insulator
black/gray, opaque, hardness 2, sheets of C atoms, electrical conductor
-
covalent produces a hardness of....
7 or higher, e.g. quartz
-
how many minerals are known in the world
~4000
-
-
elements that come from ore minerals
- iron
- lead
- zinc
- copper
- nickel
- uranium
-
... out of the 89 minerals make up >99% of earth's crust
12
-
most common in earth's crust
-
most common in whole earth
-
most abundant and simple silicates
quartz
-
besides silicon, 4 additional elements that add to minerals
Na, Ca, K, Al
-
most common crustal mineral
feldspars
-
3 most important iron-magnesium silicates
olivines, amphiboles, pyroxenes
-
ions can subsitute for other ions of similar...
Ex: Garnets
-
carbonates (percipitated out of water, used for cement)
-
oxides (metals mined and extracted)
-
halides (percipitated out of water)
halite
-
sulfates (percipitated out of water
gypsum
-
sulfides (mteals mined and extracted)
-
Type of rock formed from breakdown of pre-existing rocks
sedimentary
-
rock formed by solidification of molten rock material (magma)
igneous
-
rock formed by the transformation of pre-existing rocks, without melting, because of the effects of elevated pressure, temperature, hot fluid or all 3
metamorphic
-
....solidify quickly at surface after erupting from volcano (form little to no crystals, often layers)
volcanic/extrusive igneous rocks
-
....solidify slowly beneath the earth's surface (form large crystals slowly & massive w/out layers)
Plutonic/intrusive igneous rocks
-
Magma that reaches the surface while still molten is called...
LAVA
-
in the weathering process, fragments form....
- clastic sedimentary rock
- ex: sandstone
-
in the weathering process, dissolved ions form...
- chemical sedimentary rock
- (also is teh cement for clastic rocks)
-
lithification:
- the "making of rocks"
- 1.accumulate into beds
- 2.compressed
- 3.with cements percipitating, form a hardness
-
alters the shape/orientation of the crystals
changes some minerals into different minerals
Metamorphism
-
metamorphic vs sedimentary
metamorphic vs igneous
- meta - forms in bands (often discountinuous), with light & dark, varying in color and thickness
- meta - has a distict and different mineralogy and no signs of melting
-
why know igneous rocks & process?
- locate valuable minerals
- learn more about earth's internal processes such as plate techtonics
- avoid hazards from volcanoes
-
name 5 intrusive structures
- magma chamber
- dike (shallow errosion, cuts across layers)
- sill (cuts horizontally between layers)
- volcanic neck (devil's tower)
- batholith (deeper erosion)
-
igneous rocks are classified by...
composition (minerals present): glassy, aphanitic, porphoritic, phanaritic
texture (size of crystals): ultramafic, mafic intermediate, felsic
-
where do igneous rocks form?
- divergent boundaries/hot spots (decompression )
- convergent boudnaries (adding water)
-
The magma has the same composition as the original rock when....(and can recrystallize)
the rock melts completely
-
the relationship with temperature increase with increasing depth into earth
- Geothermal Gradient
- beneath continental crust: 30* C per km
- beneath ocean crust: 60* C per km
-
Fractional Crystalization
early-forming crystals will either settle downward or attach to the walls where the temp is coolest and grow inward. Magma changes composition continuously.
-
-
describe the volcano types
-
-
-
most explosive volcano is...
Composite (mt st helens) b/c of the gas build up
-
gases escape more readily from ....magma
low viscosity
-
viscosity = resistance to flow; depends on composition
high silica vs low silica
- high silica = high viscosity = thicker= explosive eruptions=cascade volcanos=felsic
- low silica = low viscosity =runnier = quite fluid flows = basalitc sheild volcanoes (hawaii) = mafic
-
order common igneous rocks by high to low silica content/viscosity
- rhyolite
- dacite
- andesite
- basalt
-
describe volcanic gases
- SO2 reflect sun's energy back to space and cools the earth's temperature
- acidic
- contain Pb, As, Au, Hg, etc
-
The more silicate rich the magma the .... the gas content
higher
-
elaborate on 8 volcanic eruptions:
lava flow
earthquake
landslide/tsunami
volcanic gases
direct blasts
pyroclastic flows
lahars
tephar/ash flows
- Lava flows: pahoehoe vs. a’a
- Earthquakes:
- 1) volcano-tectonic = magma movement
- 2) long period = volcanic tremor
- Landslides/Tsunamis: eruption not required
- Volcanic gases: precursor to eruption; VOG
- Directed blast: structural weakness (Mt. St.Helens)
- Pyroclastic flows: “nuee ardentes”; surges
- Lahars: eruption not required;(mud/debris flow) composite volcanoes
- Tephra/Ash fall: acute (asphyxiation) andprolonged hazard (climate change)
-
VEI
What VEI rating does a super volcano have?
- Volcanic Explosive Index
- 8
-
Composition = extrusive/intrusive
Name according to comp...
- Ultramafic = very rare/peridotite
- Mafic = basalt/gabbro
- Intermediate = adesite/diorite
- Felsic= Rhyolite/granite
-
-
increase in pressure......melting temperatures
- increase
- this means rock moving upwards tends to melt
-
felsic magma density is ....than crust density
mafic magma density is.....than crust density
mafic magma density is .....than MANTLE density
- less than
- greater than
- less than
-
why study sedimentary rocks?
- contain archive of ancient history of the planet
- preserve fossils
- derive coal, oil & natural gas
- open spaces btwn sedimentary layers acts as storage for water/oil/natural gas
-
physical weathering often takes advantage of....
- cracks
- fractures
- irregularities in rock
-
many minerals readily dissolve in water, especiialy those with....bonds
ionic
-
chemical weather occurs 3 ways:
- dissolution
- hydolysis
- oxidation
-
most abundant clastic materials
-
calcite dissolves better ....water and comes out in ....water
silica dissolves ....water and comes out in ....water
- cool water; warm water
- warm water; cool water
-
most important mineral cements
- calcite
- hematite
- quartz
- clay
-
Sedimentary rock classification determined by texture and composition
Texture determines ........nomeclature.
Composition dominates .....nomeclature.
- Clastic (grain size, sorting, rounding)
- Chemical
-
freeze/thaw, root wedging, jointing
physical weathering
-
dissolution, hydroysis, oxyidation
chemical weathering
-
classification (grain size, sorting, & rounding) allow scientists to interpret....
sediment source, weathering and erosion history
-
clastic sediemtn texture reatlates to...
- strength and steadiness of currents transporting the sediment
- distance of transport
-
3 main types of preservation in sedimentary rocks:
- original materials such as bones/teeth
- minerals replace carbon-rich compounds
- as an impression that remains in the sediment such as footprints/shell casts
-
fossil fuels (stored chemical energy from sun) form from....
organic matter disposited by sediments (plants/animals)
locating fossil fuels requires a knowledge of sedimentary rocks
-
depositional environments
the characteristics used to name sedimentary rocks can be used to interpret the history of an area that was once a lake, beack, swamp, etc.
-
graded beds implies....
ripples/cross-bedding implies....
shale layers in between indicate...
- settling of coarse then fine particles
- sediment being swept by waves before it settled
- times of slow accumulation
-
graded sandstone beds interlayered with deep water marine shale are the result of.....
turbidity currents
-
metamorphic rocks are found in....
- activiely forming mountain ranges
- always in eroded mountain belts
-
metamorphic rocks exhibit two types of change
- new minerals form
- rock texture is altered
-
raising the temperature of rock through sediment burial, tectonic burial, and magma intrusions allow the material to reach...
metamorphic conditions
-
high temp metamorphism causes...
-
mineral stability
- mineral states are stable at a fixed range of temp and pressure
- ex: water as a liquid, solid, gas
-
geothermal gradient for metamorphism: temperature increases as rocks are .....in earth's crust
buried deeper
-
recrystallization of minerals into new ....and .....
recrystallization changes rock texture without changing ... and ...
- without changing:
- chemical comp
- mineral content
-
describes planes of mineral formed in response to stress
foliation
-
the presence of ... makes metamorphic reactions occur faster and more easily.
fluid
-
...are those that form in a limited range of conditions
tell the geologist about the metamorphic conditions (b/c they're stable over a certain temp/pressure)
index minerals
- good:chlorite(low),amphibole, pyroxene
- poor: quartz, feldspars, muscovite
-
metamorphic texture is foliated or non-foliated. define....
composition depends on ... and ...
- foliated rocks all have layered minerals
- parent rock and fluids
-
Order foliated metamorphic rocks by lowest grade:
- slate
- phyllite
- schist
- gneiss
- migmatite
-
non-foliated metamorphic rock is named by its ..... as the primary characteristic
composition (mineral content)
-
most common contact metamorphic rock
hornfels
-
contact metamorphism: metamorphic grade is highest when it is located .....to the intrusion
closest
-
occurs along the boundaris of igneous intrusion and under lava flows
heat is dominant agent
contact metamorphism
-
....occurs along mid-ocean ridges/divergent plate boundaries
involves migration and raction of hot, mineral rich geopthermal FLUIDS
hydrothermal metamorphism
-
...occurs along subduction zpones and active mountain-forming zones
...occurs on a broad, large-scale
....is pressure driven
regional metamorphism
-
in regional metamorphism:
low-t/high-p occurs when parallel and ....to trench
high-t/low-p occues when parallel and ....to trench
-
paired metamorphic belts refere to .....metamorphism
-
protolith or parent rock transformation in metamorphic rocks:
limestone ->
sandstone ->
|
|
