CH. 2 - MINERALS

MINERALS

Basic building block of rocks

>4,000 minerals identified

Mineral Definition (requirements):

1) Solid

2) Naturally Occurring

Mineral Definition

3) Inorganic – no biologic origin4) Definite Chemical CompositionEx: Halite =

Quartz = Diamond =

Graphite =

Mineral Definition

5) Ordered Crystalline Structure

Ex: Halite (NaCl)

Ordered Crystalline Structure

Diamond = high pressure

- complex bonding of carbon atoms

Graphite = low pressure

- carbon atoms bond in sheets

Mineral Definition

1. Solid

2. Naturally Occurring

3. Inorganic

4. Definite Chemical Composition

5. Ordered Crystalline Structure

Structure of Minerals

1) Atom – smallest building block of an element

Composed of atomic particles

- protons (+)

- neutrons

- electrons (-)

Periodic Table of the Elements (p. 31)

Balanced Atoms

Atomic Number = number of protons

- defines which element atom belongs to

Atomic Mass = sum of protons & neutrons

Balanced Atoms

Number of electrons = number of protons

Rule:

1st energy level = 2 electrons max

All other energy levels = 8 electrons max

Balanced Atoms

Valence electrons = electrons in outermost energy level

Atoms bond b/c they want full outer shell of electrons

Types of Bonding

1) Ionic Bonding

Ion = atom with an electrical charge

- caused by losing or gaining electrons

Ionic Bonding

Atoms bond b/c opposites attract (like magnets)

Ex: Halite (NaCl)

Types of Bonding

2) Covalent Bonding

- atoms share valence electrons

- outer energy levels overlap

Ex: Oxygen (O2)

Structure of Minerals

2) Element – composed entirely of same kind of atoms

- all atoms have same number of ___________

92 naturally occurring elements

Element

Some minerals are elements:

Ex: Native Copper

Gold

Sulfur

Graphite

Structure of Minerals

3) Compound – combination of two or more elements

- characteristics are different than individual elements

Ex: Halite NaCl

Compound

Most minerals are compounds:

Quartz = SiO2

Galena = PbS (lead sulfide)

Hematite = Fe2O3 (iron oxide)

Chemical Composition of Crust

98.3% of crust composed of 8 elements (Figure 2.21)

Other 84 elements share 1.7% of remaining crust

- includes

Mineral Groups

1) Silicate Group - 90% of all minerals

Basic building block is the silica tetrahedron SiO4

4-

Silica tetrahedron (SiO44-)

Negative charge bonds with positive ions

Other abundant elements of crust are positive ions

Mineral Groups

2) Nonsilicate Group

Includes:

a) rock-forming minerals

Ex: calcite

Nonsilicate Group

b) native elements

Ex: sulfur, copper, gold

c) Metal ores

Ex: galena (PbS)

magnetite (Fe3O4)

Rocks

Aggregate of minerals (mixture)

Some rx are impure quantities of the same mineral

Ex: Limestone = calcite

(rock) (mineral)

Rocks

Most rx are composed of several minerals

Ex: Granite = quartz, feldspar, (rock) hornblende

(minerals)

3 groups of rocks

1)

2)

3)