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.

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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.