Rocks (such as basalt, granite or sandstone)
Rocks (such as basalt, granite or sandstone)
Rocks (such as basalt, granite or sandstone)
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<strong>Rocks</strong>, Minerals<br />
and other<br />
Earth Materials<br />
<strong>Rocks</strong> (<strong>such</strong> <strong>as</strong> b<strong>as</strong>alt, <strong>granite</strong> <strong>or</strong> <strong>sandstone</strong>) are made of<br />
minerals. F<strong>or</strong> example, the minerals in b<strong>as</strong>alt are mostly<br />
plagiocl<strong>as</strong>e and pyroxene.<br />
Minerals are made of elements. F<strong>or</strong> example, plagiocl<strong>as</strong>e is made<br />
of calcium, sodium, aluminum, silicon and oxygen.<br />
Will you get this concept c<strong>or</strong>rect if I <strong>as</strong>k about it on an exam?<br />
(You don’t have to know the details, just the general concept that<br />
rocks are made of minerals that are made of elements.)<br />
1<br />
2<br />
We Can View Geology at Different Scales<br />
Granite outcrop<br />
04.01.a<br />
Landscape<br />
Outcrop<br />
Hand specimen Thin section 3<br />
4<br />
Granite minerals<br />
quartz<br />
Some mineral<br />
specimens contain<br />
only one mineral.<br />
<strong>Rocks</strong> are made of Minerals<br />
5<br />
6<br />
1
Sandstone and shale<br />
Back to <strong>granite</strong><br />
Some rocks contain<br />
only one mineral.<br />
But, most contain m<strong>or</strong>e than one<br />
7<br />
8<br />
K-feldspar = pot<strong>as</strong>sium feldspar<br />
Biotite (is a mica)<br />
9<br />
10<br />
Compounds<br />
Elements<br />
Minerals are compounds:<br />
• Quartz = SiO2<br />
• K-feldspar = KAlSi3O8<br />
• Biotite = K(Mg,Fe)3AlSi3O10(OH)2<br />
F<strong>or</strong>mul<strong>as</strong> give ratios of<br />
elements in compounds<br />
Minerals are made of Elements<br />
O = oxygen<br />
Si = silicon<br />
Al = aluminum<br />
Fe = iron<br />
Ca = calcium<br />
Na = sodium<br />
Mg = magnesium<br />
K = pot<strong>as</strong>sium<br />
H = hydrogen<br />
C = carbon<br />
11<br />
Most imp<strong>or</strong>tant elements in Earth’s crust<br />
• O = oxygen<br />
• Si = silicon<br />
• Al = aluminum<br />
• Fe = iron<br />
• Ca = calcium<br />
• Na = sodium<br />
• Mg = magnesium<br />
• K = pot<strong>as</strong>sium<br />
• H = hydrogen<br />
• C = carbon<br />
12<br />
2
Average Abundances in Earth’s Crust<br />
Abundant Elements (wt% in crust)<br />
Some<br />
abundant<br />
metals<br />
Silicon is second most<br />
abundant; aluminum<br />
is third<br />
Iron is most abundant<br />
transition metal<br />
Oxygen is most<br />
abundant element<br />
04.10.b1<br />
oxygen O 46.1%<br />
silicon Si 28.2%<br />
aluminum Al 8.23%<br />
iron Fe 5.63%<br />
calcium Ca 4.15%<br />
sodium Na 2.36%<br />
pot<strong>as</strong>sium K 2.33%<br />
magnesium Mg 2.09%<br />
titanium Ti 0.56%<br />
osialfecanakmg<br />
13<br />
14<br />
Average Abundances in Earth’s Crust<br />
Average Abundances in Earth’s Crust<br />
Oxygen is most<br />
abundant element<br />
So, there is lots of b<strong>as</strong>alt<br />
and <strong>granite</strong> in the crust.<br />
Oxygen is most<br />
abundant element<br />
Silicon is second most<br />
abundant; aluminum<br />
is third<br />
Because they are made Silicon is second most<br />
of the most common abundant; aluminum<br />
minerals.<br />
is third<br />
Because oxygen and silicon are most abundant,<br />
minerals containing O and Si are most abundant.<br />
Minerals containing O and Si are called<br />
silicates.<br />
04.10.b1<br />
15<br />
Quartz, K-feldspar, pyroxene . . . These are some of the most<br />
abundant silicate minerals because they are made of the<br />
most abundant elements.<br />
04.10.b1<br />
16<br />
Average Abundances f<strong>or</strong> the Entire Earth<br />
Average Abundances f<strong>or</strong> the Universe<br />
Magnesium is<br />
abundant metal<br />
Silicon third most<br />
abundant element<br />
Oxygen second most<br />
abundant element<br />
Hydrogen is most<br />
abundant<br />
Helium is second<br />
most abundant<br />
04.10.b2<br />
Iron and nickel<br />
abundant in c<strong>or</strong>e<br />
Sulfur abundant in<br />
c<strong>or</strong>e<br />
04.10.b3<br />
17<br />
18<br />
3
Mineral compositions<br />
Mineral compositions<br />
Minerals are compounds<br />
Means we can write a f<strong>or</strong>mula<br />
Atoms are in specific ratios<br />
No matter the size of the sample<br />
C<strong>or</strong>undum is made of aluminum and<br />
oxygen<br />
H<strong>as</strong> f<strong>or</strong>mula Al 2 O 3<br />
F<strong>or</strong> every aluminum atom, there are 1.5<br />
oxygen atoms<br />
Quartz is made of silicon and oxygen<br />
H<strong>as</strong> f<strong>or</strong>mula SiO 2<br />
F<strong>or</strong> every silicon atom, there are 2<br />
oxygen atoms<br />
sapphire<br />
ruby<br />
19<br />
20<br />
Convenient division<br />
Ferromagnesian minerals<br />
Ferromagnesiam<br />
minerals<br />
Contain significant<br />
amounts of Fe and Mg<br />
Generally dark col<strong>or</strong>ed<br />
Found in rocks richest<br />
in Fe and Mg<br />
These are mafic and<br />
ultramafic minerals<br />
Other minerals (nonferromagnesian)<br />
Contain less <strong>or</strong> no Fe<br />
and Mg<br />
Generally light col<strong>or</strong>ed<br />
Found in rock po<strong>or</strong> in<br />
Fe and Mg<br />
These are felsic<br />
minerals<br />
pyroxene<br />
biotite<br />
olivine<br />
h<strong>or</strong>nblende<br />
21<br />
22<br />
Non-ferromagnesian minerals<br />
Ferromagnesian rocks<br />
Plagiocl<strong>as</strong>e<br />
(a feldspar)<br />
quartz<br />
K-feldspar<br />
b<strong>as</strong>alt<br />
mafic<br />
olivine<br />
gabbro<br />
dunite<br />
Muscovite<br />
(a mica)<br />
23<br />
Ultramafic rock<br />
24<br />
4
Non-ferromagnesian rocks<br />
Back to <strong>granite</strong><br />
<strong>granite</strong><br />
Quartz = SiO2<br />
K-feldspar = KAlSi3O8<br />
rhyolite<br />
granodi<strong>or</strong>ite<br />
tuff<br />
Biotite = K(Mg,Fe)3(AlSi3)O10(OH)2<br />
<strong>Rocks</strong> (e.g., <strong>granite</strong>)<br />
Are made of minerals (e.g., quartz, K-feldspar,<br />
biotite)<br />
Which are made of elements (e.g., Si, K, Al, K, Mg,<br />
Fe, etc.)<br />
25<br />
26<br />
What is a mineral?<br />
What Is a Mineral?<br />
Solid<br />
Ordered internal<br />
structure<br />
Natural<br />
In<strong>or</strong>ganic<br />
Specific chemical<br />
composition<br />
mostly<br />
Which means it is<br />
crystalline<br />
27 04.01.b 28<br />
So . . .<br />
<strong>Rocks</strong><br />
Ice is a mineral, water is not<br />
“Synthetic” gems are not<br />
minerals, natural ones are<br />
Clam shells are not minerals,<br />
but calcite is<br />
Volcanic gl<strong>as</strong>s is not a mineral,<br />
but quartz is<br />
Mica is not the name of a<br />
mineral, but muscovite and<br />
biotite are<br />
Natural mercury is not a<br />
mineral but cinnabar (mercury<br />
sulfide) is<br />
29<br />
30<br />
5
Observe the differences between these two rocks<br />
Observe that these rocks have m<strong>or</strong>e<br />
than one type of mineral<br />
04.02.b<br />
Composed of<br />
crystals =<br />
crystalline rock<br />
Composed<br />
of pieces<br />
(cl<strong>as</strong>ts) =<br />
cl<strong>as</strong>tic rock<br />
04.02.a<br />
Crystalline<br />
Cl<strong>as</strong>tic<br />
31<br />
32<br />
Observe that these rocks have large crystals <strong>or</strong> cl<strong>as</strong>ts<br />
(photos show the same size of polished slab)<br />
Observe the shape of crystals <strong>or</strong> cl<strong>as</strong>ts<br />
in these two rocks<br />
04.02.b<br />
04.02.b<br />
Crystalline<br />
Cl<strong>as</strong>tic<br />
Crystalline<br />
Cl<strong>as</strong>tic<br />
33<br />
34<br />
Observe the layers in these rocks<br />
Back to minerals<br />
04.02.b<br />
Crystalline<br />
Cl<strong>as</strong>tic<br />
35<br />
36<br />
6
Distinguishing One Mineral from Another<br />
Tests to Help Identify Minerals<br />
Crystal shape<br />
Cleavage<br />
No cleavage<br />
Hardness<br />
Effervescence<br />
Streak<br />
Luster<br />
Density<br />
Col<strong>or</strong><br />
Magnetism<br />
04.03.a<br />
37 04.03.b 38<br />
What Controls a Crystal’s Shape?<br />
Halite (NaCl)<br />
Internal structure of halite<br />
Orderly arrangement of<br />
atoms<br />
Atomic Arrangement<br />
Sizes and<br />
packing<br />
of atoms<br />
04.04.b<br />
Repeating<br />
pattern<br />
04.04.a 39<br />
40<br />
How Are Atoms Arranged in a Mineral?<br />
Observe some ways atoms are arranged in a mineral<br />
Atomic Scale of Mineral Cleavage<br />
Brown-yellow atoms bonded with<br />
blue atoms into flat sheets (strong<br />
bonds)<br />
Sheets joined by long bonds<br />
between sheets (break<br />
along weakest bonds)<br />
Cleave into sheets<br />
04.04.c1-3<br />
Cubic Tetrahedron Octahedron<br />
04.05.a<br />
41<br />
42<br />
7
Bonds with Same Strength<br />
Observe the number of cleavage planes in this mineral<br />
Mineral can break along<br />
three sets of planes without<br />
p<strong>as</strong>sing through an atom<br />
Mineral breaks through<br />
the atoms in nearly any<br />
direction so it will fracture<br />
04.05.c<br />
04.05.b<br />
43<br />
44<br />
Observe the number and relative <strong>or</strong>ientation of cleavage<br />
planes in this mineral<br />
Observe the number and relative <strong>or</strong>ientation of cleavage<br />
planes in this mineral<br />
04.05.c<br />
04.05.c<br />
45<br />
46<br />
Observe the number and relative <strong>or</strong>ientation of cleavage<br />
planes in this mineral<br />
Observe the number and relative <strong>or</strong>ientation of cleavage<br />
planes in this mineral<br />
04.05.c<br />
04.05.c<br />
47<br />
48<br />
8
Periodic Table<br />
Letters are abbreviation<br />
f<strong>or</strong> element<br />
What are minerals made of?<br />
04.06.a1<br />
# is atomic number<br />
(number of protons)<br />
Col<strong>or</strong> represents type of element<br />
49<br />
50<br />
Maj<strong>or</strong> Cl<strong>as</strong>ses of Rock-F<strong>or</strong>ming Minerals<br />
Oxides<br />
Carbonates<br />
Halides<br />
Cl<strong>as</strong>sifying minerals<br />
Silicates<br />
anion/group mineral<br />
group<br />
O oxide<br />
SiO 4 silicate<br />
Minerals in a group<br />
have similar properties<br />
04.06.b4<br />
CO 3 carbonate<br />
F <strong>or</strong> Cl halide<br />
SO 4 sulfate<br />
NO 3 nitrate<br />
Native minerals Sulfides Sulfates<br />
51<br />
Other groups:<br />
• sulfides<br />
• native elements<br />
52<br />
Examples: calcium minerals<br />
Examples: carbonate minerals<br />
Mn carbonate<br />
Pb carbonate<br />
CaO lime oxide<br />
Ca 2 SiO 4 larnite silicate<br />
CaSiO 3 woll<strong>as</strong>tonite silicate<br />
rhodocrosite<br />
cerrusite<br />
CaCO 3 calcite carbonate<br />
CaF 2 flu<strong>or</strong>ite halide<br />
smithsonite<br />
calcite<br />
53<br />
Zn carbonate<br />
Ca carbonate<br />
54<br />
9
Sulfides<br />
Native elements<br />
pyrite<br />
molybdenite<br />
copper<br />
graphite<br />
Both graphite and<br />
diamond are made<br />
of pure carbon<br />
chalcopyrite<br />
covellite and<br />
chalcopyrite<br />
covellite 55<br />
diamond<br />
gold<br />
sulfur<br />
56<br />
gems<br />
Silicate Minerals<br />
•Beautiful<br />
•Exotic<br />
•Durable<br />
•Snob appeal<br />
mineral<br />
gem<br />
diamond diamond<br />
beryl emerald, aquamarine<br />
c<strong>or</strong>undum ruby, sapphire<br />
quartz opal, amethyst, citrine<br />
jadeite jade<br />
Silicate<br />
tetrahedron<br />
04.07.b<br />
Tetrahedra<br />
bond<br />
together<br />
and with<br />
other<br />
elements<br />
57<br />
58<br />
Silicate minerals range from mafic to felsic<br />
Independent Tetrahedra<br />
Olivine<br />
Mafic (containing le<strong>as</strong>t Si and O)<br />
Pyroxene<br />
Amphibole<br />
04.07.c<br />
Biotite (mica)<br />
Muscovite (mica)<br />
Feldspar<br />
Quartz<br />
Felsic (containing most Si and O)<br />
Olivine<br />
Tetrahedra bond to<br />
other elements, not<br />
other tetrahedra<br />
59<br />
60<br />
10
Tetrahedra bond<br />
together to f<strong>or</strong>m<br />
single chains<br />
Single Chains<br />
Tetrahedra bond<br />
to f<strong>or</strong>m double<br />
chains<br />
Double Chains<br />
Pyroxene<br />
04.07.c<br />
04.07.c<br />
Amphibole<br />
61<br />
62<br />
Sheet Silicates<br />
Framew<strong>or</strong>ks<br />
Tetrahedra bonded together<br />
and with other elements<br />
in 3D framew<strong>or</strong>k<br />
Quartz<br />
Mica<br />
Feldspar<br />
04.07.c<br />
63<br />
04.07.c<br />
64<br />
Most significant silicates<br />
Quartz – in many igneous and metam<strong>or</strong>phic<br />
rocks, and the main component of many<br />
sedimentary rocks<br />
Quartz<br />
quartz with biotite and feldspar<br />
in <strong>granite</strong><br />
quartz<br />
crystal<br />
Feldspar – the most abundant mineral on Earth<br />
– makes up a large % of the oceanic crust<br />
Clays – s<strong>or</strong>t of like mic<strong>as</strong>, clays are the group of<br />
minerals that make up shales and related rocks<br />
– the most common kinds of sedimentary rocks<br />
65<br />
<strong>sandstone</strong> in outcrop<br />
66<br />
11
Clays<br />
67<br />
feldspar<br />
crystalline rock cl<strong>as</strong>tic rock<br />
Granite with<br />
feldspar<br />
pot<strong>as</strong>sium feldspar<br />
plagiocl<strong>as</strong>e feldspar<br />
Arkose with<br />
feldspar<br />
68<br />
Nonsilicate Minerals: Carbonates<br />
Calcite and dolomite<br />
Calcite<br />
Dolomite<br />
The key components<br />
in all limestones.<br />
Huge cliff f<strong>or</strong>mers.<br />
Lots of fossils.<br />
These minerals<br />
make up limestones<br />
04.09.a<br />
69<br />
70<br />
Nonsilicate Minerals: Halides and Sulfates<br />
Halite (halide)<br />
Nonsilicate Minerals: Oxides<br />
Magnetite<br />
table salt<br />
Hematite<br />
Gypsum (sulfate)<br />
pl<strong>as</strong>ter, sheetrock, etc <br />
Both are iron<br />
<strong>or</strong>e minerals<br />
71 04.09.a<br />
04.09.a<br />
72<br />
12
Nonsilicate Minerals: Sulfides<br />
Pyrite<br />
Galena<br />
So, what minerals are found where?<br />
Sulfides are the most imp<strong>or</strong>tant<br />
kinds of metal <strong>or</strong>e minerals.<br />
Copper<br />
sulfide<br />
04.09.a<br />
73 74<br />
Minerals in Different Parts of Earth<br />
Continental crust<br />
Oceanic crust<br />
<strong>granite</strong><br />
Quartz and K-feldspar<br />
b<strong>as</strong>alt<br />
Plagiocl<strong>as</strong>e feldspar<br />
and pyroxene<br />
Upper<br />
mantle<br />
C<strong>or</strong>e<br />
Olivine and pyroxene<br />
Fe-alloy<br />
alloy<br />
04.10.a<br />
ultramafic rock<br />
75<br />
13
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