Minerals Rocks are composed of minerals,
minerals are composed of ions
ions are composed of electrons and nucleus (protons and often neutrons).
Electro n Neutron Proton Nucleus CHEMISTRY Atom
Addition of an electron to an atom = ion anions are larger than atoms and are negatively charged.
Removal of an electron from atom = cation cations 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 CaCO 3 Ca 2 + = cation CO 3 2- = anion complex
Definition of Mineral 1. naturally occurring 2. definite chemical composition (within limits)
H 2 O Al 2 O 3 corundum sapphire ruby
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 present 2. arrangement of elements in the mineral structure
Polymorph- same chemical formula but different atomic structure, e.g.: FeS 2 pyrite marcacite CaCO 3 calcite aragonite AND???
C graphite diamond
Minerals are formed (crystallize) from: 1. solution 2. magma 3. gas 4. 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 FeS 2 PbSZnS iron leadzinc pyrite galenasphalerite b)Oxides Fe 3 O 4 Fe 2 O 3 Al 2 O 3 Iron oxide iron oxide aluminum oxide magnetite hematite corundum
c) Native elements AgAu Pt CuC Silver gold platinum copper graphite diamond d) Carbonates CO 3 2- Carbon and oxygen CaCO 3 (Ca,Mg)CO 3 Calcitedolomite Calcium carbonateCalcium, magnesium carbonate
CaCO 3 + HCl CaCl 2 + H 2 O + CO 2 Calcite hyrochorlic calcium water carbon acidchloride dioxide effervescence “bubbling”
e) Sulfates SO 4 2- CaSO 4 H 2 O Calcium sulfate (hydrous) gypsum
Nitrates, phosphates, etc.