Minerals

Rocks are composed of minerals,

minerals are composed of ions

ions are composed of electrons and nucleus (protons and often neutrons).

Electron

Neutron

ProtonNucleus

CHEMISTRY

Atom

Addition of an electron to an atom = ionanions are larger than atoms and are negatively charged.

Removal of an electron from atom = cationcations are smaller than atoms and are positively charged.

Anionic complex- a group of ions acting as a single unit (negatively charged).

NaCl Na+ = cation Cl- = anion

CaCO3 Ca2+ = cation

CO32- = anion complex

Definition of Mineral

1. naturally occurring2. definite chemical composition (within limits)

H2O

Al2O3 corundumsapphireruby

3. Definite atomic structure (crystalline not

glass).

Box 2.3.2

Metallic Bonding

Super sharing of the electrons

The properties of each mineral are determined by:

1. chemical elements present2. arrangement of elements in the mineral structure

Polymorph- same chemical formula but different atomic structure, e.g.:

FeS2 pyrite

marcacite

CaCO3 calcite

aragonite

AND???

C graphite diamond

Minerals are formed (crystallize) from:

1. solution2. magma3. gas4. metamorphism

Mineral Classification

Based on anion or anionic complex.WHY?

1. Anions and anionic complexes control the atomic structure (that in turn controls physical properties—cleavage, density, etc.)

2. They control the chemical properties

3. Minerals with the same anions and anionic complexes tend to occur together

a)Sulfides

FeS2 PbS ZnS

iron lead zincpyrite galena sphalerite

b)Oxides

Fe3O4 Fe2O3 Al2O3

Iron oxide iron oxide aluminum oxidemagnetite hematite corundum

c) Native elementsAg Au Pt Cu C Silver gold platinum copper graphite

diamond

d) Carbonates CO32-

Carbon and oxygen

CaCO3 (Ca,Mg)CO3

Calcite dolomiteCalcium carbonate Calcium,

magnesium carbonate

CaCO3 + HCl CaCl2 + H2O + CO2

Calcite hyrochorlic calcium water carbon acid chloride dioxide

effervescence “bubbling”

e) Sulfates SO42-

CaSO4 • H2O

Calcium sulfate (hydrous)

gypsum

Nitrates, phosphates, etc.