EESC 2200The Solid Earth System
Minerals & Rox22 Sep 08
IsostasyContinental Tectonics
Homework 1:Due Today
ES101--Lect 5
Minerals
rock forming
gems & ores
ES101--Lect 5
Plate Tectonics can produce all
rock classes:
• igneous
• sedimentary
• metamorphic
ES101--Lect 5
Earth is made of rocks
Each rock is made up of grainsminerals
ES101--Lect 5
Feldspar
Quartz
Mica
ES101--Lect 5
basaltfrom Hawaiiwitholivine
basalt
ES101--Lect 5photomicrograph of basalt
Feld-spar
Oli-vine
(x-polars)
ES101--Lect 5
What Are Minerals?
Naturally occurring,
solid substances,
with a specific chemical compositions
and crystal structure.
Structureof anAtom
Ionic Radiiof some
geologicallyimportant ions
Carbon Atoms in Diamondand Graphite
Graphite
Diamond
Bonding effectson
Physical Properties
3.5 g/cc
2.1 g/cc
ES101--Lect 5
Graphite
Diamond
0 1000 2000
50
100
150
Temperature (°C)
Depth(km)
One Mineral or Two?
ES101--Lect 5
Graphite
Diamond
0 1000 2000
50
100
150
Temperature (°C)
Depth(km)
Polymorph! same chemical comp'n, different shape
Galena (PbS)
Ionic Bonding
ES101--Lect 5
H
Li
Na
Fr
Be
Mg
Ca
Ra
Sc
Y
Ac
Ti
Zr
Hf
V
Nb
Ta
Cr
Mo
W
Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
He
Ne
Ar
Xe
Rn
F
Cl
I
At
O
S
Te
Po
N
P
Sb
Bi
C
Si
Sn
B
Al
In
Tl
Cd
Hg
Ag
Au
Pd
Pt
Rh
Ir
Ru
Os
Tc
Re
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Pa
K
Rb
Cs
Sr
Ba La Pb
Th U
Periodic Table of the Elements
common in crust and mantle crust
ES101--Lect 5
ChartMg Si
Ca "rest"
Fe Al
Elemental Composition of the Earth(no core)
by weight
Si - SiliconMg - MagnesiumFe - IronAl - AluminumCa - Calcium
O - Oxygen not shown
ES101--Lect 5
Si
AlFe
CaMg
Na K "rest"
Abundance of Elements
Crust Mantle
ChartMg Si
Ca "rest"
Fe AlNa - sodiumK - potassium O - Oxygen not shown
ES101--Lect 5
The Silicates
Silicate Tetrahedron (SiO4)4-
Si4+
O2-
Basic Element:
ES101--Lect 5
=
Building block of the EarthVery strong Si-O bonds
ES101--Lect 5
Form Minerals By:1. Combining w/ Other Cations
most important: Olivine
4-
2+2+
Mg2SiO4
ES 101-Lect 6Olivine
ES 101-Lect 6
Olivine
• Main mineral in upper mantle
• In igneous rox in crust
• Dense
• Green
• Gem = peridot
(Mg,Fe)2SiO4
ES 101-Lect 6
Single Tetrahedron
Double:
Single Chain
Double Chain
Sheet 3D!
ES 101-Lect 6
Most Important Silicate Minerals
"rock-forming"
• Olivine• Pyroxene• Feldspar• Quartz• Mica• Amphibole
ES 101-Lect 6
Single Tetrahedron
Double:
Single Chain
Double Chain
Sheet 3D!
ES 101-Lect 6
Pyroxenes
e.g., CaMgSi2O6 = diopside
Fe, Mg, Ca, Mn, Na, Al
Single Chain silicate
Common in mantle, oceanic crust rocks
ES 101-Lect 6Diopside, Pyroxene
ES 101-Lect 6
Main mantle rock: Peridotite
• Mostly Olivine
• some pyroxene
(green)
(black, green)
ES 101-Lect 6
Si
AlFe
CaMg
Na K "rest"
The Crust:Need minerals that hold
Al - AluminumCa - CalciumNa - SodiumK - Potassium...more Si
K+ Fe2+
ES 101-Lect 6
Single Tetrahedron
Double:
Single Chain
Double Chain
Sheet3D!
ES 101-Lect 6
Feldspars
KAlSi3O8
CaAl2Si2O8NaAlSi3O8
• Makes 60% of crust
Holdslight largecations
plagioclase
"K-spar"
3D!
ES 101-Lect 6Orthoclase K-Feldspar
ES 101-Lect 6
-- No cations ("pure")
Common in continental crust
SiO2
Pure silica: Quartz
3D!
ES 101-Lect 6Quartz
ES 101-Lect 6
Single Tetrahedron
Double:
Single Chain
Double Chain
Sheet 3D!
ES 101-Lect 6
Just Add Water!• Silicates react, form more open structures
Pyroxenes + H2O -> Amphiboles
+
H2Odouble chain
ES 101-Lect 6Hornblende, Amphibole
ES 101-Lect 6
Others + H2O -> Sheet Silicates
clays, micas, serpentines
Just Add Water!
sheet
ES 101-Lect 6
Big gaps betweensheets:• Very weak bonds• Holds Water
• Makes "platy" minerals Cleavage
Micas sheet
ES 101-Lect 6
• Absorbant clays
• Common upper crust, weathering
Clayssheet
Clay minerals:
formed fromsheets of silica tetrahedra
ES 101-Lect 6
Two General Forms:
Serpentines: > 95% of all asbestos
Amphiboles: "blue asbestos"
Asbestos sheetvs.
double
ES 101-Lect 6Serpentine
ES 101-Lect 6
Theme:
Molecular structure affects
mineral structure
ES 101-Lect 6
Silicatetrahedra
Dense
LightIons
Mg2+
Fe2+
Ca2+
Al3+
Na1+
K1+
man
tle
crus
t
3D!
ES101--Lect 5
Feldspar
Quartz
Mica
ES 101-Lect 6
Major Rock-forming Minerals-> Silicates: SiO2 based
• 95% of crust, upper Mantle SiO
OO
O
ES 101-Lect 6
Major Rock-forming Minerals-> Silicates: SiO2 based
• 95% of crust, upper Mantle
-> Carbonates: CO3 based• Common near-surface (limestones,...) -- Major Carbon store
C
O
O
SiO
OO
O
ES 101-Lect 6
Major Rock-forming Minerals-> Silicates: SiO2 based
• 95% of crust, upper Mantle
-> Carbonates: CO3 based• Common near-surface (limestones,...) -- Major Carbon store
-> OthersOxides (various settings)Sulfides, Sulfates (S = sulfur)
C
O
O
SiO
OO
O
Rock Types• All rocks are organized according to genesis (igneous,
sedimentary or metamorphic), composition and texture• Igneous
– Mafic (silica poor) to felsic (silica rich)– Aphanitic (finely crystalline) to phaneritic (coarsely crystalline)
• Sedimentary– Clastic– Chemical and/or biochemical
• Metamorphic– Protolith (what was it before being heated and/or deformed?)– Contact (heating) vs. regional metamorphism (heating and
deforming)
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