For Monday, MINERALS! Read Chapter 2, pay close attention to p. 30-37, then the rest. Know the whole chapter before your GLY 111 lab.

Here are some key concepts to study:

Rock, Mineral

Element, Atom, Proton, Neutron, Electron, Nucleus,

Energy Level Shell, Ion, Isotopes,

Compounds, Bonding, Crystals,

Polymorphism, Ionic substitution,

Elemental abundances.

Mineral families:

Silicates (learn lots about Silicates!),

Carbonates,

Halides,

Sulfides,

Oxides.
 
 
 

1. Rock = aggregate of minerals (one or more)

2. Mineral = naturally occurring, inorganic solid with a characteristic chemical composition and a crystalline structure.

3. Chemical Elements are fundamental substances made of Atoms, which are made of:

- Protons - positive charge - same mass as neutrons

- Neutrons - no electrical charge - same mass as protons

- Electrons - negative charge - very tiny mass

- Nucleus - center of atom where Protons and Neutrons hang

- Energy Shells - orbits of electrons around the nucleus. Shell-like clouds of electrons.

4. Ions are atoms which lose or gain electrons due to unstable electron energy shells:

- Cations - positively charged ions (too few electrons) Na+, Ca+2, K+, Fe+2

- Anions - negatively charged ions (too many electons) Cl-, Fl-, O-2

- Complex Ions - ions composed of more than one atom bonded together:CO3-2, SiO4-4, SO4-2

5. Isotopes are atoms which lose or gain neutrons (change in mass, no change in charge).

6. Compounds are unions of anions and cations in specific ratios. They stick together because the ions are bonded in one of several ways:

- covalent bonds: shared electrons (diamond, water)

- ionic bonds: attraction between oppositely charged ions (NaCl).

- metallic bonds: covalent bonds sharing inner energy-level electron shells (tighter bond). Leaves outer electrons free to roam.

- van der Waals bond (graphite and talc) - weak electrostatic bond connecting molecules

7. Crystals - Chemical compounds that have atoms arranged in distinctive geometric patterns.

8. Polymorphism - the ability of a specific chemical compound to crystallize with more than one type of crystal strucure

9. Ionic Substitution - elemental substitution in a crystal lattice.

Ex. Ca+2 and Sr+2 are approx. same size. Sr+2 substitutes freely into calcite (CaCO3) structure. Celestite (strontium carbonate) is rather rare in nature, although very pretty blue. Al3+ in for Si4+.

Common Earth Elements:
 
Whole Earth   
Abundances: 		 Crustal   
Abundances: 
Iron (Fe) 35% Oxygen (O)  47%
Oxygen (O) 30% Silicon (Si)  28%
Silicon (Si)  15% Aluminum (Al)  8%
Magnesium (Mg)  13% Iron (Fe)  5%
Nickel (Ni) 2% Calcium (Ca)  4%
Sulfur (S) 2% Magnesium (Mg)  2%
Calcium (Ca)  1% Sodium (Na)  3%
Aluminum (Al)  1% Potassium (K)  3%
....everything else is less than one percent. This composition has a profound affect on the types of minerals that we find on earth.

Minerals are natural inorganic solids with a distinctive chemical composition and a specific crystalline structure.

1. Main Mineral families named according to their anions (you'll run into these in lab, too). Read about these in the book.
 
Oxides O  
(FeO2) 		 Sulfides S  
(FeS2) 
Halides Cl,F  
(NaCl) 		 Carbonates CO3  
(CaCO3) 
Sulfates SO4  
(CaSO4) 		 Phosphates PO4  
(CaPO4) 
Silicates SiO4  
(KAlSi3O8) 		 Hydroxides OH  
(Al(OH)3) 
2. Silicate Minerals: The most abundant rock forming minerals (why??)

Based on the complex anion called the Silica Tetrahedron, SiO4-4. Each silica tetrahedron has a charge of -4 (count 'em).

Family of silicate mineral groups: polymerization of tetrahedrons (how many tetrahedrons are bonded):

3-D Frameworks Quartz and Feldspar

2-D Continuous Sheets Mica

Double chains Amphibole

Single chains Pyroxene

Isolated polymer groups Epidote and Beryl

Isolated tetrahedra Olivine Group

Physical Properties of Minerals:

Crystal form - geometry of freely-grown mineral.

Luster - reflected light -- Metallic or Non-Metallic

Color - rarely diagnostic, often helpful.

Streak - color of a powdered mineral when scraped against a porcelain plate.

Hardness - resistance to abrasion. Mohs Scale: 10 minerals from softest to hardest, Talc - Gypsum - Calcite - Fluorite - Apatite - Orthoclase - Quartz - Topaz - Corundum - Diamond. Fingernail (2.5), Penny (3), Glass and Stainless Steel knife (5.5).

Cleavage - tendancy to break along flat surfaces. These represent planes of weakness in the atomic crystal lattice. Muscovite, calcite, halite.

Fracture - quartz has a conchoidal fracture, like broken glass. Some are fibrous (asbestos).

Density (specific gravity).

Special Characteristics:

- Taste (halite, sylvite).

- Acid solubility, others.