I. Introduction


-mineral- a naturally occurring, inorganic, crystalline solid, with a narrowly defined chemical composition, and characteristic physical properties.


-rock- a consolidated aggregate of minerals (or particles of other rocks).


-minerals are made up of elements. (ex. mineral halite made up of elements sodium and chlorine)


II. What does Matter Consist of?


-Matter: Anything that has mass and occupies space.

The three states of matter (phases): solids, liquids, and gases.


Elements and Atoms


-element- substance that can't be broken down into other substances by ordinary chemical means.  92 naturally occurring elements have been discovered (Table 2.3).


-atom- smallest part of an element that retains the properties of that element.  Cannot be split into by conventional means.


-atoms made of 3 kinds of particles: protons, neutrons, electrons.


1- proton- particles with a positive electric charge (has mass).


2- neutron- particle with no electric charge (electrically neutral) (has mass).


3- electron- particle with a negative electric charge (~no mass).  Orbit rapidly around the nucleus at specific distance.


-models of atoms (fig. 2.6):


-nucleus- central area of atom composed of protons and neutrons (~all mass here).


-shells- electron bearing layers that orbit the nucleus.


-The nucleus is only about 1/100,000 of the diameter of an atom.


-atomic number- number of protons in each atom (Table 2.3).


-atomic mass number- total number of neutrons and protons in an atom.


-isotopes- atoms containing same number of protons but different numbers of neutrons.  Some isotopes are radioactive (ex. Carbon 14) (Figure).


Bonding and Compounds


-bonding- process by which atoms are joined to other atoms.


-compound- substance formed when atoms of 2 or more different elements are bonded.


-ionic bonding- bonding due to the attraction between + charged ions and - charged ions; (electron transferred to other atom); the most common type of bonding in minerals (Ex. NaCl) (fig. 2.8a ; fig. 2.8b).


-covalent bonding- bonding due to the sharing of electrons by adjacent atoms (fig. 2.10).


-Metallic and van der Waals Bonds:
metallic: Extreme type of electron sharing (gold, silver)

VDW: Week (residual) attractive forces (between sheets of graphite


III. Minerals

-Most composed of 2 or more elements; Ex. Quartz  =  SiO2 (1 Si for every 2 O).


-A few minerals composed of just 1 element ; Ex.  Gold (Au), diamond (C);single elements= native elements


Mineral- a naturally occurring, inorganic, crystalline solid, with a narrowly defined chemical composition, and characteristic physical properties.


1) naturally occurring- not man made (diamonds, emeralds, rubies).


2) inorganic- excludes animal and vegetable matter (coal).


2) crystalline- atoms arranged in a regular 3-D framework; may exhibit crystal faces or cleavage;  glass- amorphous = w/o form. (Figure 2.11)


4) solid- no liquids or gasses (water not; ice is mineral).


5) narrowly defined chemical composition-chem. analysis will always give ~same chem. comp.  Some minerals have constant chemical composition (SiO2; NaCl)), others have a range of compositions, olivine (Mg,Fe)2SiO4


6) Physical Properties of Minerals- all minerals have physical properties that are ~constant for a given mineral and therefore aid in mineral identification; common physical properties include:


-color, luster, crystal form, cleavage, fracture, hardness, specific gravity, etc.


IV. Known Minerals


-over 3500 minerals known to exist, but only ~2 dozen are common


- only 8 elements make up over 98% of earth's crust (91 naturally occurring) (Table 2.4)


-by far most abundant elements are O and Si, usually combined with one or more of the other 6 elements.


-O & Si combine to form a group of minerals called the silicates (SiO4)-4


V. Mineral Groups

Ggeologists divide minerals into groups that have the same negatively charged ion or ion group; several groups (Table 2.5):


-silicates: 1/3 of all known minerals, but make up 95% of earth's crust; Ex. Quartz, SiO2


-other silicates contain one or more other elements; Ex. K-feldspar, KAlSi3O8; Olivine, (FeMg)2SiO4


-silica tetrahedron: basic building block of all silicate minerals (fig. 2.14)


-(SiO4)-4 not stable isolated; how make silica tetrahedron electrically neutral (stable)?


1)    add + charged ions (ex. Fe++, Mg++, Ca++, Al+++)

2)    share Oxygen atoms w/ other tetrahedra (usually a combination of 1 & 2)


-structure of silicate minerals: (fig. 2.15)


-4 different ways silica tetrahedrons are combined:

Isolated tetrahedra, Continuous chains, Continuous sheets, 3-D frameworks (fig 2.15).


-Silicate mineral divided into 2 groups depending on which +ions present:


1) ferromagnesian silicates; silicate minerals containing Fe, Mg, or both.

-dark colored and more dense (olivine, pyroxene, amphibole, biotite).


2) nonferromagnesian silicates; lack Fe and Mg

-lighter colored, less dense (quartz, K-feldspar, plagioclase, muscovite).


-Carbonate and Other mineral groups:

Carbonates; (CO3)-2; Calcium carbonate; Calcite; limestone.

Oxides; Hematite (Fe2O3); Magnetite (Fe3O4)

Sulfides; (S-2) Galena PbS

Sulfates; (SO4)-2 Gypsum (CaSO4.2H2O)

Halides; (Cl-1) Halite (NaCl) (Table 2.5).


VI. Mineral Identification

-     color & luster (metallic and nonmetallic)

-     crystal form (fig 2.11)

-     cleavage (fig 2.21) & fracture

-     hardness

-     specific gravity (ratio of weight / weight of equal volume of water)


VII. Rock forming minerals


-        Rocks are aggregates of one or more minerals.

-  rocks most commonly composed of silicates (Table 2.7).


VIII. Mineral Resources and Reserves

-resource- total concentration of material in such a form and amount that economic extraction is currently or potentially feasible; most nonrenewable because used up much faster than they can be replenished.


-classified as metallic (gold, iron), nonmetallic (sand, gravel, sulfur), or energy (uranium, coal, oil, natural gas) resources.


-reserve- the part of the resource that can be extracted economically.

-whether a deposit is a resource or a reserve depends on such things as concentration, transportation costs, labor costs, market price, and technological developments.