Welcome to GLG101C Introduction to Geology Fall 2004 Professor James Tyburczy
Department of Geological Sciences
	Class Notes -- Chapter 3

Amethyst Galleries has many beautiful photos of minerals from all over the world

The US Geological Survey's Mineral Resources Program has statistics and information on the worldwide supply, demand, and flow of minerals and materials essential to the U.S. economy, the national security, and protection of the environment.

The University of Arizona has a great site showing movies of crystal models how they vary with temperature and pressure.

Here's alocation to download a pdf file from the US Geological Survey on asbestos.

Here's the Asbestos Institute site, emphasizing safe use of chrysotile asbestos.

For a map of the soil shrinking/swelling potential for the Phoenix area see: http://www.az.nrcs.usda.gov/technical/soils/shrinkswell.html

Chapter 3. MINERALS: BUILDING BLOCKS OF ROCKS

• Elements, atoms, and isotopes
• Atoms - Protons, neutrons, and electrons
• Atomic number, atomic mass, atomic weight.
• Isotopes: same # of protons, different # of neutrons in nucleus
• Cations, anions - atoms lose or gain electrons and become electrically charged

Chemical Bonding - ionic, covalent, metallic

• Crust - O, Si, Al most abundant; Fe, Ca, Na, K, Mg next most abundant; all other elements much less abundant
• Mantle - O, Si, Mg, Fe, ...
• Core - Fe, Ni, ...

• Silica tetrahedron: (SiO4)-4 - basic building block
• Charge balance in a mineral is achieved by adding positive ions and/or by linking tetrahedra

• Single chain - pyroxenes
• Double chain - amphiboles

• Calcium-rich (plagioclase) feldspar - framework silicate; Ca, Na, Al rich
• Potassium feldspar (orthoclase) - framework silicate; K, Al rich
• Quartz - framework silicate - pure SiO2
• Pyroxene - single chain silicate; Fe, Mg rich (examples: Augite, diopside)
• Amphibole - double chain silicate; Fe, Mg, Al rich, also contains H (or water). Examples hornblende, tremolite
• Micas and clays - sheet silicates
1. some are K, Al rich (the light micas - muscovite).
2. Some are Fe, Mg, K, Al rich (the dark micas - biotite)
3. All contain H (or water)
   
• Olivine - isolated silica tetrahedra; Fe, Mg rich

• Native elements - gold (Au), copper (Cu), silver (Ag)
• Sulfides - pyrite FeS2
• Sulfates - gypsum CaSO4.2H2O
• Carbonates - calcite-(CaCO3, most common non-silicate mineral) - limestone
• Chlorides - halite (NaCl - table salt)
• Oxides - hematite, magnetite, ice

• Color, streak, luster, hardness (Mohs' hardness scale), crystal form, cleavage/fracture, specific gravity, (taste, magnetism, ....)

• asbestos - a term meaning fibrous aggregates of minerals

1. 'white asbestos' is serpentine, a sheet silicate (specific mineral is chrysotile)
        NOT medically dangerous, except when one works with the fibers all day
        95 % of all asbestos in the US is 'white asbestos'
   
   
2. 'blue' and 'brown' asbestos - amphibole minerals (double chain silicates)
         Very dangerous medically, but only constitutes a small fraction of the asbestos in use in the U.S. today

For a map of the shrinking/swelling potential for the Phoenix area see: http://www.az.nrcs.usda.gov/soils/shrinkswell.html