UNIVERSITY OF SOUTH ALABAMA
GY 111: Physical Geology
Lecture 5: Mineral Classification
Instructor: Dr. Douglas W. Haywick
Last Time
1. Elementary Chemistry (atomic structure)
2. Isotopes
3. The Periodic Table
4. Bonding
Web notes 4:
Fluorite: CaF2
Copper: Cu
Calcite: CaCO3
Source: csm.jmu.edu
Atoms & Atomic Particles
Na
Cl
• The sodium-chlorine pairing is called a molecule
• Molecules are composed of uncharged atoms and/or
charged atoms (ions)
• An atom is the smallest component of an element that
can retain the properties of that element
Atoms & Atomic Particles
• Atoms are composed of 3 fundamental particles:
1) Protons 2) Neutrons 3) Electrons
• Protons & Neutrons always reside in the center of the atom
termed the nucleus
• Electrons are always located in the electron cloud in complex
orbitals where they “orbit” the nucleus
Electron Cloud (Electrons)
Nucleus (Protons + Neutrons)
Atoms & Atomic Particles
• Proton: has a mass of 1 and a positive charge
• Neutron: has a mass of 1 and a neutral charge
• Electron: has a mass of 0 and a negative charge
• The number of protons and neutrons in the nucleus is variable
and defines the different chemical elements (refer to the
periodic table)
• For an uncharged atom:
# of protons = # of electrons
Atomic Number & Weight
• By convention, we put both numbers on a letter that
symbolizes that particular element:
1H1
2He4
Atomic
Number
Atomic
Weight
6C12
Isotopes
• The number of protons and electrons for an element does
not vary, but the number of neutrons can. e.g., hydrogen
+
-
-
-
1H1
1H2
1H3
Proton
Neutron
-
Electron
Isotopes
• The number of protons and electrons for an element does
not vary, but the number of neutrons can. e.g., hydrogen
+
-
-
-
1H1
1H2
1H3
Stable
Unstable
Simple atomic structure:
Source:http://www.amptek.com/xrf_3.gif
Level
(n)
"Name"
# of electrons
(2n2)
1
K
2
2
L
8
3
M
18
4
N
32
5
O
50
The Periodic Table
8 electronss in outer shell
7 Es in outer shell
6 Es in outer shell
5 Es in outer shell
4 Es in outer shell
3 Es in outer shell
2 electrons in outer shell
1 electron in outer shell
The Periodic Table
Already have filled shells
Gain 1 electron
Gain 2 electrons
Gain 3 electrons
Loose/gain 4 Es
Loose 3 electrons
Loose 2 electrons
Loose 1 electron
Chemical Bonding
Chemical Bonding
Three Major types:
1) Ionic bonding; exchange of electrons between atoms
to form ions
Na+
Cl-
Chemical Bonding
Three Major types:
1) Ionic bonding; exchange of electrons between atoms to
form ions
2) Covalent bonding: sharing of electrons between atoms
-
-
-
-
-
-
-
-
-
Cl2
-
Chemical Bonding
Three Major types:
1) Ionic bonding; exchange of electrons between atoms to
form ions
2) Covalent bonding: sharing of electrons between atoms
3) Metallic bonding: freely exchangeable electrons
between nuclei
Bonding (Properties)
Bond
Mineral properties
Ionic
-strong bond
-high melting points
-vitreous lusters
-higher solubility
Covalent
- strong bonds
- hard minerals
- very high melting points
- vitreous – adamantine lusters
Metallic
- weak bonds
- low to high melting points
- metallic lusters
-electrically conductive
Today’s Agenda
1. Crystal Chemistry (Crystallography)
2. Mineral Classification (“classes”)
3. The Silicates
Web notes 5 and 6
Atomic Packing:
The Issue: How do you build 3-dimensional crystals
(minerals) from atoms, ions and molecules?
Atomic Packing:
Minerals are assembled according to exact chemical “blueprints”…
Atomic Packing:
Minerals are assembled according to exact chemical “blueprints”…
… and those blue prints are controlled by exact mathematical and
physical laws.
Atomic Packing:
1) Atoms/ions make up
minerals
2) Atoms take up space
3) How do you pack
differently sized atoms
in space to make up minerals?
2 dimensions
Source: http://www.mines.edu/academic/courses/met/mtgn311/visual.html
Atomic Packing:
3 dimensions
Source: http://www.mines.edu/academic/courses/met/mtgn311/visual.html
Crystal Structures:
NaCl
(Halite)
Source: www.chm.bris.ac.uk
Crystal Structures:
CaF2
Source: http:\\staff.aist.go.jp
(Fluorite)
2+
-Ca
-F
Polymorphs:
Two minerals with the same chemical composition but
different crystal structures
e.g. Graphite (C)
Diamond (C)
Crystal Structures:
These are pretty pictures only. You do NOT have to
know this stuff for the exam(s)
Crystal Structures:
Al2O3
(Ruby)
Source: http:\\staff.aist.go.jp
3+
-Al
2-O
Crystal Structures:
CaCO3
(Calcite)
2+
-Ca
Source: http:\\staff.aist.go.jp
2-O
- C4+
Crystal Structures:
CaCO3
(Aragonite)
Source: http:\\staff.aist.go.jp
2+
-Ca
2-O
- C4+
Crystal Structures:
MgFeSiO4
Source: http:\\staff.aist.go.jp
(Olivine)
Crystal Structures:
K(Mg,Fe)3AlSi3O10(OH,F)2
Source: http:\\staff.aist.go.jp
(Biotite)
Why classify minerals?
Why classify minerals?
 At last count, there are well over 4000 distinct
“minerals” in our solar system
Source: www.icminerals.com
Source: www.csm.jmu.edu
Source: www.icminerals.com
Why classify minerals?
Why classify minerals?
At last count, there are well over 4000 distinct
“minerals” in our solar system
They are composed of 90+ elements, as well as more
complex ions like CO32-, SO42-, PO43- etc.
Source: www.webchem.net\csm.jmu.edu
Mineral Classification
Mineral Classification
Quartz
Mineral Name
Mineral Classification
SiO2
Chemical Formula
Mineral Classification
Si4+
O2-
O2-
Graphic representation (formula)
Source: http:\\staff.aist.go.jp
Mineral Classification
Graphic representation (crystal structure)
Mineral Classification
The simplest way to classify minerals is by their
anionic composition
Mineral Classification
Class
I
Name
Native Elements
Anion(s)
none
Examples
Dominant
Bond
Metals: Gold, Copper, Silver
Semi-metals: Arsenic (As)
Non-metals: diamond, graphite, sulfur
Metallic
Covalent
II
Sulfides
S-
Pyrite, Chalcopyrite, Galena
III
Oxides\hydroxides
O2- OH-
hematite, magnetite, limonite
IV
Halides
Cl-, Fl-
halite, fluorite
V
Carbonates
CO32-
calcite, aragonite, malachite
VI
Sulfates
SO42-
gypsum, anhydrite
VII
Phosphates
PO43-
apatite
VIII
Silicates
SiO44-
>3000 (i.e., most minerals)
Chalk board time
Largely
Ionic
Silicate Classification
Silicate Classification
SiO4
4-
The basic silicate tetrahedra
Silicate Classification
The basic silicate tetrahedra (ball and stick)
Silicate Classification
The basic silicate tetrahedra (just sticks)
Silicate Classification
All silicates have the basic tetrahedra in their structures,
but there are 7 distinct silicate classes
Chalk board time
Silicate Classification
Nesosilicates
(garnet, olivine)
(0 shared oxygen)
Sorosilicates
(1 shared oxygen)
Cyclosilicates
(2 shared oxygens)
Inosilicates
(pyroxenes)
(2 shared oxygens)
Inosilicates
(amphiboles)
(2 ½ shared oxygens)
Phyllosilicates
(micas)
(3 shared oxygens)
Silicate Classification
Tektosilicates
(quartz, feldspars)
(4 shared oxygens)
Today’s Homework
1. Download and read web notes 5 and 6
Next Time
1) Quiz 3: short answer (compare and contrast)
2) Volcanoes and volcanism
GY 111: Physical Geology
Lecture 5: Mineral Classification
Instructor: Dr. Doug Haywick
dhaywick@southalabama.edu
This is a free open access lecture, but not for commercial purposes.
For personal use only.