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) is an example of a native element.

* ____________: The smallest individual particle that retains the properties of an element.

* ____________: A charge atom .

-- Cations: positively charge ions.

-- Anions: negatively charged ions. 

* _____________: 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 of a naturally occurring compound.

STRUCTURE OF THE ATOM

* PROTON: mass of 1 and a charge of +1

* NEUTRON: mass of one and a neutral charge.

* ELECTRON: negligible mass and a charge of -1.

* ATOMIC NUMBER: The number of protons in the nucleus .

* ATOMIC MASS (or weight): The number of protons and neutron in the nucleus

* ISOTOPES: elements with the same atomic number but different atomic masses

How is the Periodic Table of Elements organized? (fig. 2.6)

EXAMPLES:

 Hydrogen

Helium 

 Hydrogen isotopes

Carbon isotopes:

The "Solar System" Model (fig. 2.2b)

What are Energy Levels? (fig. 2.2c)

First level

Second level

Third level

Fourth level

What is the "Octet Rule"?

Hydrogen verses Lithium

Sodium Cation

Chlorine Anion

What are "valence electrons"?

 Why are they important?

Examples of ionization (e.g. Na and Cl ions)-fig. 2.7

CHEMICAL BONDS are chemical processes by which individual atoms become attached to one another to form molecules.

* _____________ BOND (fig. 2.4): 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) fig. 2.9

* ________________ BOND (fig 2.5): A strong bond formed by the sharing of electrons by adjacent atoms. e.g. Diamond (C) - fig. 2.8; Water (H₂O)

* ________________ BOND: A weak bond formed by the electrostatic residual charge on the surface of adjacent atoms. e.g. Graphite(C) -fig. 2.15B

 POLYMORPHS of Carbon:

What are the 3 phases of H₂O, and what are the variables controlling their occurrence?

Where do diamonds come from and how do we know?

* _________________ 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 (fig 2.14) determines packing order.

Packing order determines CRYSTAL GEOMETRY (fig. 2.11); for exampleÖ

Quartz (SiO₂): a hexagonal crystal

Pyrite (FeS₂): a cubic crystal

Galena (cubic crystal)

Fluorite (a cubic crystal)

Halite (cubic crystal)

________________ (fig. 2.23, 2.24): The tendency for minerals to break along parallel planes of weak bonding. Types of cleavage 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 Fracture (Quartz)

Fibrous Fracture (Asbestos)

Irregular Fracture

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 streak of mineral (important in pigments)-fig. 2.26

________________: the way light is reflected off a mineral's surface (table 2.3).

MOHS HARDNESS SCALE: (see extra credit assignment) - table 2.2

_____________________: 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 properties

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 %
Oxygen (O)	46.6%
Silica (Si)	27.7%
Aluminum (Al)	8.1%
Iron (Fe)	5.0%
Calcium (Ca)	3.6%
Sodium (Na)	2.8%
Potassium (K)	2.6%
Magnesium (Mg)	2.1%
	98.3%

MAJOR MINERAL FAMILIES (see also table 2.1)

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(CaSO4ï2H2O)
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 (fig. 2.16).

* Single Tetrahedron(fig, 2,17a)) e.g. Olivine [(Mg,Fe)₂SiO₄]

* Single Chain Silicate (fig. 2.17b): Pyroxene [Ca(Mg,Fe)SiO₃]

* Double Chain Silicate(fig. 2.17c): Amphibole [Ca₂(Fe,Mg)₅SiO₂₂(OH)₂]

* Sheet Silicates (fig. 2.17d): 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 (fig. 2.18): Quartz and Feldspars

--QUARTZ (SiO₂)

--FELDSPARS 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.

--- Orthclase 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.

--- Plagioclase 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-FORMING SILICATES

Olivine	(Mg,Fe)2SiO4
Pyroxene	Ca(Mg,Fe)SiO3
Amphibole	Ca2(Fe,Mg)5SiO22(OH)2
Biotite	K(Fe,Mg)3AlSi3O10(OH)2
Muscovite	KAl2(AlSi3O10)(OH)2
Plagioclase	(Ca,Na)AlSi3O8
Orthoclase	KAlSi3O8
Quartz	SiO2

MAFIC minerals are Fe/Mg-rich, and are poor in SiO, e.g.:

1)

2)

3)

4)

FELSIC minerals have little Fe/Mg, and have a high % SiO, e.g.:

1)

2)

3)

4)

MAJOR MINERAL FAMILIES

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. Halite*

3. Fluorite*

4. Pyrite

5. Galena*

6. Calcite*

7. Graphite*

8. Quartz*

9. Gypsum*

10. Magnetite*

11. Talc*

12. Olivine

13. Biotite

14. Muscovite

15. Orthoclase

16. Plagioclase

17. Corundum*

18. Pyroxene

19. Amphibole