Class
Notes: Geo 1330: Dr Dupre
MINERALS
A ROCK is a solid,
naturally occurring mixture (or aggregate) of minerals or mineral-like
substances.
What is a MINERAL?
* Naturally occurring
* Inorganic
* Crystalline
* Solid, with a
* Consistent Chemical Composition
ATOMIC STRUCTURE
* ____________: A
substance that cannot be decomposed into a simpler substance by ordinary
chemical or mechanical means. Copper (Cu) and diamonds (C) are examples.
* ____________: The
smallest individual particle that retains the properties of an element.
* ____________: A
charged atom .
-- Cations: positively charged.
--Anions: negatively charged.
* _____________: A molecule formed by the chemical
bonding of two or more elements.
* _____________: The
smallest unit that has the distinct chemical properties of a compound. Quartz
(SiO2) is an example. So is the first mineral you ever came in
contact with!
STRUCTURE OF THE ATOM
__________: mass of
1and a charge of +1
__________: mass of
one and a neutral charge.
__________: negligible
mass and a charge of -1.
* ________________:The
number of protons in the nucleus .
*
________________(a.k.a. atomic weight): The number of protons and neutron in
the nucleus
* _______________:elements
with the same atomic number but different atomic masses
How is the Periodic
Table of Elements organized?
EXAMPLES:
Hydrogen
Atomic Mass =?
Atomic Number =?
Helium
Atomic Mass =?
Atomic Number =?
Hydrogen
Isotopes
Carbon Isotopes:
The "Solar
System" Model
Q. What is an
energy-level shell?
A.
First level (K) has electrons
Second level (L) has electrons
Third level (M) has electrons
Fourth level (N) has electrons
Hydrogen verses Lithium
Q. What are "valence
electrons"?
A.
Q. Why are they important?
A.
Q. What is the
"Octet Rule"?
A. In chemical
reactions, non-metal ions (excluding Hydrogen and Helium) tend to
Sodium Cation
Chlorine Anion
Examples of ionization
(e.g. Na and Cl ions)
CHEMICAL BONDS are
chemical processes by which individual atoms become attached to one another to
form molecules.
_____________ BOND: An
intermediate strength bond formed by an electrical attraction of ions of
opposite charge. Approximately 90% of all minerals have this type of chemical
bond.
e.g. Halite (NaCl)
________________ BOND:
A strong bond formed by the sharing of electrons by adjacent atoms.
e.g. Water (H2O)
Diamond (C)
fig.2.8;
________________ BOND:
A weak bond formed by the electrostatic residual charge on the surface of
adjacent atoms.
e.g. Graphite(C)
POLYMORPHS of
Carbon:
Q. What are the 3 phases
of H2O, and what are the variables controlling their occurrence?
A.
Q. Where do diamonds
come from and how do we know?
A.
*
_________________BOND: A bond where freely mobile electrons are shared and
dispersed among ions (which accounts for the high electrical conductivity of
metals). e.g. Copper(Cu) and Gold (Au)
PHYSICAL PROPERTIES OF MINERALS (see also
table 2.4)
1) Crystal form
2) Cleavage
3) Fracture
4) Color
5) Streak
6) Luster
7) Hardness
8) Specific Gravity
(~density)
9) etc
IONIC RADIUS determines
packing order.
Halite
Packing order
determines CRYSTAL GEOMETRY; for example
Pyrite (FeS2): a cubic crystal
Quartz (SiO2):a
hexagonal crystal
Galena (cubic crystal)
Fluorite (a cubic crystal)
Halite (cubic crystal)
etc
________________: The
tendency for minerals to break along parallel planes of weak bonding. Types are
defined by the number of planes of symmetry and the angle of the planes to one
another. e.g. cubic (Halite, Galena), rhombic (Calcite), and octahedral
(Fluorite)
_________________: The
way in which minerals with no cleavage break. e.g.
Conchoidal (Quartz)
Fibrous (Asbestos)
Irregular
COLOR: e.g. sulfur,
copper, pyrite, malachite
Inherent coloration: e.g .Malachite
Exotic coloration: Quartz e.g. amethyst, citrine, smoky, rose quartz
Corundum is a common abrasive
(emery),yet with a trace of Cr you have a red Ruby ;with a trace of
Fe+Ti you get a blue Sapphire.
__________________:the
color of a powdered mineral (important in pigments)
________________: the way
light is reflected off a mineral's surface (table 2.3).
MOHS HARDNESS SCALE: (see extra credit assignment) -
_____________________:The
ratio of the weight of the mineral to the weight of an equal volume of water.
It is a dimensionless measure of density. Most minerals have a S.G.
of approx. 2.7 (e.g. quartz, halite, feldspar). Some. however, are much more
dense(e.g. galena - 7.5 and gold - 20!)
OTHER PROPERTIES:
Magnetite (Fe3O4)-
magnetic
Calcite (CaCO3) - fizzes with weak
acid
Halite (NaCl) - taste
Graphite (C) - greasy feel
Fluorite and some varieties of calcite
fluoresce under UV light
Eight elements
constitute over 98% of the continental crust!
|
ELEMENT |
WEIGHT % |
|
|
46.6% |
|
|
27.7% |
|
|
8.1% |
|
|
5.0% |
|
|
3.6% |
|
|
2.8% |
|
|
2.6% |
|
|
2.1% |
|
|
98.3% |
MAJOR
MINERALFAMILIES
|
Silicates: (SiO4)-4
|
e.g. Quartz(SiO2) |
|
Native Elements: |
e.g. Copper (Cu);
Diamond (C) |
|
Carbonates: (CO3)-2
|
e.g. Calcite
(CaCO3) |
|
Sulfides: S-2
|
e.g. Pyrite (FeS2),
Galena (PbS) |
|
Oxides: O-2
|
e.g. Magnetite
(Fe3O4) |
|
Sulfates: (SO4)-2
|
e.g. Gypsum(CaSO4•2H2O) |
|
Halides: e.g. (Cl)-2
|
e.g. Halite (NaCl);
Fluorite (CaF2) |
|
Phosphates (PO4)-3
|
e.g. Apatite |
SILICATE MINERALS (approximately 90% of all
minerals in the crust!)
Silica-Oxygen
Tetrahedron (SiO4)-4::
the basic building block of silicate minerals
* Single
Tetrahedron e.g. Olivine [(Mg,Fe)2SiO4]
* Single Chain Silicate:
Pyroxene [Ca(Mg,Fe)SiO3]
* Double Chain Silicate: Amphibole [Ca2(Fe,Mg)5SiO22(OH)2]
* Sheet Silicates:
e.g. Mica and Clay minerals
--Micas include
---Biotite[K(Fe,Mg)3AlSi3O10(OH)2
]
---Muscovite [KAl2(AlSi3O10)(OH)2]
--Clays include many
minerals, including Kaolinite
* 3-Dimensional Silicates
_____________________
(SiO2)
--_____________________
are the most common mineral group found in the earth's crust. All feldspars are
Aluminum Silicates, and their weathering products form the primary source of Al
ore deposits. I will subdivide the feldspars into Orthoclase and Plagioclase
feldspars.
--- ________________
feldspar has Potassium as a major cation (KAlSi3O8),
and is most abundant in granites. It is the pink mineral in the
granite("Texas Pink") forming the steps of S&R 1.
--- __________________feldspars
are actually a series of minerals where Ca and Na are mixed in differing
amounts by a process of solid solution, as represented by (Ca,Na)AlSi3O8.I
will refer to the end members of this solution series as Ca-Plagioclase and
Na-Plagioclase.
MAJOR ROCK-FORMINGSILICATES
|
|
(Mg,Fe)2SiO4 |
|
|
Ca(Mg,Fe)SiO3 |
|
|
Ca2(Fe,Mg)5SiO22(OH)2
|
|
|
K(Fe,Mg)3AlSi3O10(OH)2
|
|
|
KAl2(AlSi3O10)(OH)2
|
|
|
(Ca,Na)AlSi3O8 |
|
|
KAlSi3O8 |
|
|
SiO2 |
____________ minerals
are Fe/Mg-rich, and are poor in SiO, e.g.:
1)
2)
3)
4)
____________ minerals
have little Fe/Mg, and have a high % SiO, e.g.:
1)
2)
3)
4)
MAJOR
MINERALFAMILIES
|
Silicates: (SiO4)-4
|
e.g. Quartz (SiO2) |
|
Native Elements: |
e.g. Copper (Cu);
Graphite (C) |
|
Carbonates: (CO3)-2
|
e.g. Calcite
(CaCO3) |
|
Sulfides: S-2
|
e.g. Pyrite (FeS2),
Galena (PbS) |
|
Oxides: O-2
|
e.g. Magnetite
(Fe3O4) |
|
Sulfates: (SO4)-2
|
e.g. Gypsum (CaSO4.2H2O) |
|
Halides: e.g. (Cl)-2
|
e.g. Halite
(NaCl); Fluorite (CaF2) |
|
Phosphates (PO4)-3
|
e.g. Apatite
(CaPO4) |
For more on mineral
uses check out this WEBSITE!
You should be able to
match the following minerals with their formulas, however you will not have to
be able to reproduce the formulas. In addition, you should know a major use of
those minerals marked with an *.
1. Apatite*
2. Talc*
3. Fluorite*
4. Gypsum*
5. Orthoclase
6. Calcite*
7. Corundum*
8. Quartz*
9. Diamond*
10. Olivine
11. Pyroxene
12. Amphibole
13. Biotite
14. Muscovite
15. Plagioclase
16. Galena*
17. Graphite*
18. Halite*
19. Magnetite*
20. Pyrite