Solid Lithospheric Phases J. D. Price PE I & Geo I – ERTH 1010 & 1100.
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Transcript of Solid Lithospheric Phases J. D. Price PE I & Geo I – ERTH 1010 & 1100.
Solid Lithospheric PhasesSolid Lithospheric PhasesSolid Lithospheric PhasesSolid Lithospheric Phases
J. D. Price
PE I & Geo I – ERTH 1010 & 1100
MineralsMinerals
• Naturally occurring• Crystalline• Inorganic• Materials
• Not man made• Symmetric atomic lattice• Not life compounds
Cartoon atomsCartoon atoms
Recall Z defines the behavior of the atom (makes it elemental)
N can vary for an element (isotopes)
Example 12C = 6N + 6Z , 14C = 8N + 6Z
Not an accurate picture
Electrons too large and too close to nucleus
Movement is not oval
Distribution is trickier
Which model is more plausible
Scale
Atoms
Electron
Neutrons
Proton
Atoms
Electron
Neutrons
Proton
Mass
9.109 E -31 kg
1.673 E -27 kg
1.673 E -27 kg
Mass
9.109 E -31 kg
1.673 E -27 kg
1.673 E -27 kg
Charge
(-) 1.602 E -19 coul.
(0) None
(+) 1.602 E -19 coul.
Charge
(-) 1.602 E -19 coul.
(0) None
(+) 1.602 E -19 coul.
Electrons are attracted to protons because opposite charges attract.
The number of protons dictates the maximum number of electrons - each element has a limit to the number of electrons
The electrons control the behavior of the atom - each element behaves differently
Electrons are attracted to protons because opposite charges attract.
The number of protons dictates the maximum number of electrons - each element has a limit to the number of electrons
The electrons control the behavior of the atom - each element behaves differently
s orbitals, l = 0p orbitalsl = 1, m = -1,0,1
d orbitalsl = 2, m = -2, -1, 0 , 1, 2
f orbitall = 3
m = -3, -2, -1, 0, 1, 2, 3
Atoms may lose electrons
They become ions!
We note the charge difference in integers (e.g. +1)
For many atoms, the first electron is easy to remove, but additional electrons are not.
IonsIons
Single Electron (hydrogen atom) Multiple electron*
*exact energies vary with Z
ReactionReaction
A few elements can add electrons (right side of periodic table).
This makes negatively charged ions that may attract positive ones.
Can only attract so far – “solid spheres”
Ionic bondingIonic bonding
Incr
ease
dow
n a
grou
pDecrease across a period.
When moving across a period of main group elements, the size decreases because the effective nuclear charge increases.
Neutral Atom Size
Two hydrogen atoms in close proximity can share their electrons so that each takes on an electronic structure similar to He – a noble gas.
The diatomic H-H system:
Covalent bondingCovalent bonding
There are 90 Natural Elements
Only a few elements occur as single atoms in nature (Col VIIIA). Most are bonded to one or more other atoms through:
•Interactions with electrons
•Ionic (atomic) charge (+ attracts -)
Single elements may bond to each other entirely covalently.
Compounds (two or more elements) attach through a combination of ionic and covalent bonding.
Boded atoms make molecules, chains, or lattices.
These are compounds (polyatomic materials)
There are 90 Natural Elements
Only a few elements occur as single atoms in nature (Col VIIIA). Most are bonded to one or more other atoms through:
•Interactions with electrons
•Ionic (atomic) charge (+ attracts -)
Single elements may bond to each other entirely covalently.
Compounds (two or more elements) attach through a combination of ionic and covalent bonding.
Boded atoms make molecules, chains, or lattices.
These are compounds (polyatomic materials)
CompositionComposition
Nickel2.0%
Aluminum1.5%
Iron33.3
Calcium1.8%
Sodium0.2%
Magnes.2.1%
Others
Silicon15.6%
Oxygen29.8%
Nickel2.0%
Aluminum1.5%
Iron33.3
Calcium1.8%
Sodium0.2%
Magnes.2.1%
Others
Silicon15.6%
Oxygen29.8%
Oxygen46.6%
Silicon27.7%
Others1.4%
Magnes.2.1%
Potassium
Sodium
Calcium3.6%
Iron5.0%
Aluminum8.1%
Oxygen46.6%
Silicon27.7%
Others1.4%
Magnes.2.1%
Potassium
Sodium
Calcium3.6%
Iron5.0%
Aluminum8.1%
Bulk EarthBulk Earth CrustCrust
These are the elements from which we can make compounds - combinations of elements. Most minerals are made of these.These are the elements from which we can make compounds - combinations of elements. Most minerals are made of these.
While not all elements are able to combine, there are millions of compounds
But a much smaller number occur in nature
Even a smaller number occur near the surface of the Earth. What limits the number?
Consider this: Ca + O = CaO
More energy* Less energy*
CaO+ SiO2 = CaSiO3
*At near-surface temperatures and pressures
Energy controls it allEnergy controls it all
Applying a force (or pressure) may result in motion. This force through a distance is known as work. Energy is the quantifiable ability to do work.
Energy = Work = Force x distance = mass x acc. x dis
Work and EnergyWork and Energy
The Joule is Nm or kg m2 / s2 or the energy needed to
move a charge of 1 coulomb through a potential of 1
volt
1 joule is approximately equal to:
•6.2415 ×1018 eV (electronvolts)
•0.2390 cal (calorie) (small calories, lower case c)
•2.3901 ×10−4 kilocalorie, Calories (food energy,
upper case C)
•9.4782 ×10−4 BTU (British thermal unit)
•2.7778 ×10−7 kilowatt hour
Units of EnergyUnits of Energy
A force applied in doing work goes into overcoming a A force applied in doing work goes into overcoming a resistance, which causes a change in energy...resistance, which causes a change in energy...
Resistance Change in energy
Inertia Increase in Kinetic E
Fundamental Forces (gravity, magnetism, electrostatic…)
Increase in Potential E
Friction Increase in heat
Shape (springs, elasticity) Increase in Potential E
Umech
Fire - radiant energy from chemical energy
It is the universal term in our current physical understanding of nature.
The energy in gravitationally driven galaxies
The energy that binds subatomic particles.
The primary rule (First Law of Thermodynamics): energy cannot be created or destroyed. It must be converted. In any system, you have what you have.
Like accounting - you can keep track of conversions but the total never changes.
Energy operates at all scales!Energy operates at all scales!
The Earth is a dynamic place, conditions change (e.g. T,P) for materials on the move. What may be the lowest energy form deeper in the earth may be excessive near the surface.
Therefore, changes in compounds are possible. Please note: change is never instantaneous, requires time and/or additional energy.
Example: you place a small ice cube at 0 oC into water at 25 oC
H2Oice = H2Oliq
Ice takes a few minutes to become liquid and consumes heat to do so.
Energy is the universal currency, and nature appears to be on a budget
Energy is the universal currency, and nature appears to be on a budget
Two terms that describe a compound
Composition: the number of atoms of each element present in a compound
CaSiO3: one Ca for every one Si and three O
Structure: how the atoms are bonded to one another
CaSiO3: one Ca bonded to a O, bonded to one Si, bonded to three O…
A compound with consistent properties (composition & structure) is a phase:
CaO, SiO2, and CaSiO3 are different phases
H2O as a liquid is a different phase than H2O as a solid
CompoundsCompounds
Oxygen46.6%
Silicon27.7%
Others1.4%
Magnes.2.1%
Potassium2.6%
Sodium2.8%
Calcium3.6%
Iron5.0%
Aluminum8.1%
If these are the elements of the crust – what compositions are most likely to be present?
Some chemical nomenclature
MO (metal oxygen) oxide
e.g. CaO = calcium oxide
MNO (metal-nonmetal-oxygen) nonmetalate
e.g. CaSiO3 = Calcium silicate
Q: Which of the above elements are metals and nonmetals (including semiconductors)?
Metals (M) prefer to lose electrons
Metals, nonmetals, semiconductorsMetals, nonmetals, semiconductors
Recall the states of matter: gas, liquid, solid.
Solid Earth scientists typically use the following nomenclature for structural phase types:
“fluid” liquid or gas
“glass” solid, but not crystalline
“mineral” solid and crystalline
Major structural differences
CrystallineCsCl
CrystallineSiO2
GlassSiO2
Crystalline solids are made of strongly bonded atoms. Compounds may have different structural arrangements given energy constraints.
Ideally, scientists apply different names to phases of different solid structures
Q: why no mention of different structures in liquids or gasses?
Solid structuresSolid structures
From Klein and Hurlbut, 1999
Examples of structureExamples of structure
Transmission electron image of a pyroxene. Scale bar is 0.88 nm. Bright areas have fewer atoms.
Penn and Banfield, 1999
High resolution transmission electron image of an anatase. Scale bar is 0.88 nm.
Note repetition of pattern in 2D in both images. The repeated occurrence of atoms is called a lattice.
QuickTime™ and aTIFF (Uncompressed) decompressor
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Transmitted Electron MicroscopyTransmitted Electron Microscopy
High-resolution TEM uses interference of the electron interaction with the material.
TEM sends electrons through a thin film of the mineral. Electrons are stopped by the atoms.
Several structures that result from two things:
The bonds between atoms
The size of each atom
Halite - NaCl Fluorite – CaF2
Q: What ultimately controls structure?
Bringing atoms together –Bringing atoms together –
Note alternating Na and Cl atoms (1 Na for every 1 Cl)
There is a bond (electron movement and charge attraction) holding each Na to each Cl: outlining this makes a cubic pattern
We may also outline the relationship between atoms. 1 Na is attached to 6 nearest Cl: octahedron
These two subsets of the above model are the same with respect to bonding
A pinch of NaCl… A pinch of NaCl…
The energy available for reactions is known as Free Energy
Depends on
1. The nature of the bonding
2. Pressure
3. Temperature
4. Degree of disorder
Graphite - steep dG/dP
Diamond - higher initial G, shallow dG/dP
The Carbon SystemThe Carbon System
Image modified from Zoltai and Stout, 1984
Diamond’s excited state
Crystalline CarbonCrystalline Carbon
The Hardest material
Diamond
A soft material
Graphite
Why can we observe graphite and diamond at the same time?
There is a place where both phases share the same G, but at room T, this is ~14 kbar (14,000 x atmospheric)!
Phase DiagramPhase Diagram
Recall that as you go into the Earth, both P and T increase
These two variables control phase stability of compositions in the earth.
On the left is a map for phases of carbon
HardnessHardness
The variety of bonding between elements gives individual minerals an unique hardness.
Mohs hardness scale provides a useful relative comparison among common minerals
Lattices that are strongly bonded in two dimensions but are weak in one break into sheets.
Graphite and micas (right) are two examples of minerals with sheet cleavage
Cleavage is the official term given to a minerals ability to break along a lattice plane.
CleavageCleavage
Two directions of cleavageTwo directions of cleavage
3 directions of cleavage3 directions of cleavage
FractureFracture
Some minerals do not easily break along a plane(s). The result is fracture.
Image from Perkins, 1998
When atoms are bonded together in repeating lattices, they build geometric shapes.
Common shapes are known as habits
HabitHabit
Common habits in mineralsCommon habits in minerals
All of this controlled by two parameters:
The internal organization of the atoms
The energy between the surface and the surrounding medium.
a) Cube
b) Octahedron
c) Prism and pinacoids
d) Hexagonal prism and pyramid
e) Dodecahedron
f) Orthorhombic prism and pinacoid
g) Rhombohedron
h) Prism
Penn and Banfield, 1999
What makes a bubble round?
Could those same forces work for crystals?
What’s the difference between this atom
And this one
The greater anisotropy of the structure, the more this is a problem!
Controls on external shapeControls on external shape
Q: Which is the more stable configuration of 36 atoms?
From Blackburn & Dennen, 1998
Growth Facets
Polished Facets
ColorColor
Color is only useful for some minerals
Some exhibit a number of colors, others have a diagnostic range.
Streak - Soft minerals will powder on a hard surface. The color of the powder is typically more useful than that of the whole specimen
Bond model Outline models
Because each Si is surrounded by four O, the outline shape is a tetrahedron
Q: Where are Si and O on the periodic table?
Basic structure for silicate minerals
Basic structure for silicate minerals
Isolated silicate tetrahedra
Q: Where might we find additional elements in this structure?
-2 +2
NesosilicatesOlivine
NesosilicatesOlivine
Forsterite Mg2SiO4
Fayalite Fe2SiO4
Image from mineral.galleries.com
GarnetGarnet
X3Y2(ZO4)3
Spessartine Mn3Al2(SiO4)3
Almandine Fe3Al2(SiO4)3
Pyrope Mg3Al2(SiO4)3
Grossular Ca3Al2(SiO4)3
Uvarolite Ca3Cr2(SiO4)3
Andradite Ca3Fe2(SiO4)3
Image from mineral.galleries.com
Other nesosilicates and subsaturates
Other nesosilicates and subsaturates
Zircon Zr(SiO4)
Titanite CaTiSiO5
Topaz Al2SiO4(F,OH)2
Aluminosilicate Al2SiO5 {AlAl(SiO4)O}
Andalusite - Sillimanite - Kyanite
Staurolite (Fe, Mg,Zn)2Al9[(Si,Al)4O16]O6(OH)2
Image from mineral.galleries.com
Single chain of tetrahedraSingle chain of tetrahedra
Top
Side
-4
+2
Top
Q: where are the non-silicate components in this structure?
Inosilicates (singles)Pyroxene
Inosilicates (singles)Pyroxene
Orthopyroxene - hypersthene
Enstatite Mg2Si2O6
Orthoferrosilite Fe2Si2O6
Clinopyroxene - Augite
Diopside CaMgSi2O6
Hedenbergite CaFeSi2O6
Image from mineral.galleries.com
Wollastonite CaSiO3
Rhodonite Mn2+0.9Fe2+
0.02Mg0.02Ca0.05SiO3
Pyroxmangite Mn2+0.8Fe2+
0.2SiO3
Image from mineral.galleries.com
PyroxenoidsPyroxenoids
Top
Side
Double chain of tetrahedraDouble chain of tetrahedra
-4
+2
Top
Q: where are the non-silicate components in this structure?
Image from mineral.galleries.com
Double Chain Silicate TetrahedraDouble Chain Silicate Tetrahedra
Hornblende
(Ca,Mg,Fe,Al)6-7(Al,Si)8O22(OH,F)2
Amphibole AsbestosCrocidoliteNa2Fe2+
3Fe3+2(Si8O22)(OH)2
Top
Side
Sheet structure silicatesSheet structure silicates
Q: where are the non-silicate components in this structure?
Sheet silicateSheet silicate
Muscovite
KAl2(AlSi3O10)(OH,F)2
Biotite
K(Mg,Fe)3(AlSi3O10)(OH,F)2
Image from mineral.galleries.com
Phyllosilicate AsbestosChrysotile
Mg3(Si2O5)(OH)4
Q: Is all asbestos the same?
ClaysClays
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KaoliniteRalph L. Kugler, Milwaukee Public Museum
Kaolinite Al2Si2O5(OH)4 Polymorphs (kaolinite group)halloysite, dickite and nacrite
Silicate sheets (Si2O5) bonded to gibbsite layers (Al2(OH)4). The silicate and gibbsite layers are tightly bonded together with only weak bonding existing between the s-g paired layers.
ClaysClays
Smectite-Montmorillionite Group
smectite, pyrophyllite, talc, vermiculite, sauconite, saponite, nontronite and montmorillonite
(Ca, Na, H)(Al, Mg, Fe, Zn)2(Si, Al)4O10(OH)2 - xH2O
Gibbsite layer is partly replaced by Brucite-like layer. Variable amounts of water molecules lie between the s-[g or b]-s sandwiches.
Image from mineral.galleries.com
Illite Group Hydrobioitite, illite, brammalite
Hydrated muscovite
(K, H)Al2(Si, Al)4O10(OH)2 - xH2O
These are the minerals most commonly found in shales. More variable water between s-g-s configurations
TEM images of hydrothermal alteration from smectite to illite (scale = 0.5 µm)
ClaysClays
Clay grains are very small - reflecting the domains of mineral alteration.
Resolution requires atomic-scale electron techniques or XRD
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Red - mostly high swelling
Blue - less 50% high swelling
Orange - mostly moderate swelling
Green - less than 50% moderate swelling
Brown - little to no swelling
Yellow - no dataUS Soils - USGS
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K Taylor Marl (Ca-clays)
Top Side
Framework silicates
Q: where are the non-silicate components in this structure?
Feldspar
(Ca,Na,K,Al)(Al,Si)3O8
Images from mineral.galleries.com
Quartz
SiO2
Framework Silicate TetrahedraFramework Silicate Tetrahedra
Q: What is unique about the structure of framework silicates?
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SiO2SiO2
Quartz | Coesite | Stishovite
mineral.galleries.com
De minuscules cristaux de quartz ont une disposition radiale autour de la coesite : ceci montre que le quartz se forme au d 師 riment de la coesite (LPA)
High birefringence Stishovite in coesite, synthetically grown by J. Mosenfelder, CalTech.
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Cristobalite nodules within a vitrophere - Snowflake obsidianRockhoundblog.com
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gemandmineral.com
Tridymite crystal, from deposit associated with Mono Lakes volcano.
SiO2SiO2
SiO2SiO2Agate | Jasper | Chert | Flint | Chalcedony
Agate is name applied banded rocks made of microcrystalline quartz, typically made of fibrous quartz, called chalcedony. Colors result from impurities within the crystals
Chert and flint are homogenous chalcedony - often related to fossilizationLace agate / www.lhconklin.com
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Silica saturation in water is quite low at ambient conditions, pH=7, but increases rapidly with T. Note that amorphous silica has a higher solubility than quartz, Rimstidt & Cole 1983.
opal
Image from Klein and Hurlbut, 1985
Opals are made of spheres of silica and water - not exactly a mineral.
Feldspars Plagioclase FeldsparAnorthite (CaAl2Si2O8)
Feldspars Plagioclase FeldsparAnorthite (CaAl2Si2O8)
Alkali Feldspar
Albite (NaAlSi3O8)
Orthoclase (KAlSi3O8)
Images from mineral.galleries.com
Other important (but less abundant) nonmetals
Carbon, Sulfur, Chlorine
Carbonates (MCO3)
Calcite CaCO3
Sulfates (MSO4)
Anhydrate CaSO4
Gypsum CaSO4 2H2O
Halides (MH) metal-halogen (F, Cl)
Halite NaClImages from
mineral.galleries.com
Of course you can combine a single nonmetal with a metal
Oxides (MOx)
Magnetite Fe3O4
Sulfides (MSx)
Pyrite FeS2
Image from mineral.galleries.com
Q: Why are these are called ore minerals?
Native ElementsGold AuSilver AgDiamond CGraphite CSulfur S
Images from mineral.galleries.com
Great Ores – little to no refining involved, but very limited in availability
Single element solids
We’ve mentioned a number of minerals
Know:
What two elements are present in each 1.) silicate, 2.) sulfate and 3.) carbonate.
The different structures of silicates
What type of element is present in halides
What element must be present in 1.) oxides and 2.) sulfides
What makes a native element mineral
Keep these notes handy:
Know where to find the specific minerals named and their composition.