Geology Department

Home page

Lectures

Geology 110 Syllabus


NON-SILICATES

 

BondsSilicates

 

I. DEFINITIONS

A. Non-silicates

1. Non-silicates are minerals other than silicate minerals

2. Less complex than silicates

3. Economically important

B. Ore Mineral

1. Minerals that can be profitably extracted

2. Often contain impurities

C. Impurities

1. Do not constitute part of the mineral formula

2. Are always present

3. Sometimes give minerals their color

II. QUARTZ

A. Quartz (SiO2)

1. Used to make computer chips

2. Rarely pure

B. Many varieties

1. Rose quartz--color due to titanium impurities

2. Smoky quartz--appearance due to U, K, or Th impurities

3. Amethyst--Purple color due to Mn impurities

4. Milky quartz

a. Appearance due to microscopic fluid inclusions

b. Fluid contained in these inclusions can yield information about sea water composition through geologic time

III. NON-SILICATE MINERALS (6 classes)

A. Oxides

1. Oxides contain various types of cations bonded to oxygen (O-2)

2. Corundum (Al2O3)

a. One of the hardest naturally occurring minerals (H=9)

b. Used as an abrasive

c. Contains impurities

d. Gem stones include: red=ruby and blue=sapphire

3. Hematite (Fe2O3)

a. Found in local area

b. Streaks yield reddish color

c. Forms Red Mountain Formation near Birmingham

4. Magnetite (Fe3O4)

a. Dark gray

b. Magnetic

B. Sulfides

1. Sulfides contain various types of cations bonded to sulphur (S-2)

2. Pyrite (FeS2) "fool's gold"

a. Gold color

b. Green streak

c. Brittle

d. Crystal faces are striated

3. Chalcopyrite (CuFeS2)

a. Like pyrite, but more yellowish

b. Contains copper

4. Galena (PbS)

a. Greyish color

b. Very dense

5. Sphalerite (ZnS) (zinc sulfide)

a. Yellowish green streak

b. Powder has "rotten egg" odor

C. Carbonates

1. Carbonates consist of various cations bonded to (CO3)-2 cleavage in three directions, but not at 90o degrees.

2. Calcite (CaCO3) effervesces in HCl

3. Dolomite (CaMg(CO3)2) effervesces in HCl when powdered

D. Sulfates

1. Sulfates consist of cations bonded to sulfate group (SO4)-2

2. Gypsum (CaSO4)--used in construction

E. Halides

1. Halides consist of cations bonded to chlorine (Cl-) or flourine (F-)

2. Halite (NaCl)

a. Common table salt

b. Known as "rock salt," used to soften hard water

3. Flourite (CaF2) (Calcium flouride)--used in manufacture of toothpaste

F. Phosphates

1. Phosphates consist of cations bonded to a phosphate group (PO4)-3

2. Apatite (Ca5(F,Cl,OH)PO4)3--what teeth are made of