1-1    Minerals vs. Rocks:

1-1-1    Rocks: aggregates of minerals, normally more than one kind. Granite has quartz, feldspar, etc.. Sometimes one type of mineral, e.g. calcite in limestone.

1-1-2    Minerals:

  Natural occurring. Thus, synthetic materials such as manmade diamond are not.
  Have definite chemical composition and internal structure. Thus glass is not.
  Solid. Thus, water is not.
  Inorganic. Thus, coal is not.

1-2    Composition and Structure of Minerals:

1-2-1    Atoms:

  Basic particles that make up the element and thus the substances.
  Atoms from the same element are alike, and from different elements are different, e.g. O atom in H₂O and in CO₂ are the same. But O atom is different from H atom.
  Composed of nucleus and electrons. Within nucleus there are protons and neutrons.
  Neutron have no charge. Each proton has one "+" charge while each electron has one "-" charge.
  The whole atom is electrically neutral since the number of protons = the number of electrons.

1-2-2    Ions:

  When atoms lose or gains electrons.
  Cations have "+" charge due to loss of electrons, e.g. Na⁺.
  Anions have "-" charge due to gaining of electrons, e.g. Cl^-.
  Interaction between cations and anions are called ionic bonds, which hold the cations and anions together.

1-3    Properties of minerals:

1-3-1    Crystal form:
  Shape of crystals, some are cubic, and others are rhombohedral .
  Reflect the internal arrangement of its composing atoms.

1-3-2    Luster:

  Light reflection from the surface of minerals
  Classified as metallic and nonmetallic (hand specimens)

1-3-3    Color:

  For transparent minerals, color is the composite spectrum that passes through the minerals.
  For opaque minerals, color is the composite spectrum that is reflected from the surface of the minerals.
  Color is the least reliable physical properties for mineral identification. The following links show that quartz can have many different colors, so are feldspar and fluorite.

1-3-4    Streak:

  The color of a mineral in its powder form.
  Sometimes, the color and the streak will be different for a mineral.
  To test you need a ceramic plate, then scratch the mineral against it, color left on the plate is called.
  To test the streak, the hardness of the mineral must be less than the hardness of the ceramic plate. Otherwise, you are scratching the plate and the streak will be from the plate.
  Streak more important than color in identifying minerals.

1-3-5    Hardness:

  A measure of resistance against abrasion.
  Use Mohs scale.

1	2	3	4	5
Talc	Gypsum	Calcite	Fluorite	Apatite
6	7	8	9	10
Feldspar	Quartz	Topaz	Corundum	Diamond

Hardness of common tools:

  Glass, knife 5.5
  Copper penny 3.5
  Finger nail 2.5

1-3-6    Cleavage: the tendency to break along weak planes

Distinguish cleavage from crystal form:

  there is only one crystal form in each direction, once the form is broken you lose it.
  cleavage has a set of plane parallel to each direction, you can generate a new piece by breaking the old one.

1-3-7    Specific gravity:  

  Weight of a mineral to the weight of water having the same volume. 
  Metallic minerals normally have high S. G.

1-3-8    Other properties:

  Magnetism.
  Fluorescence and phosphorescence. You may click the following links to see more: 1, 2, 3, 4, 5. 
  Radioactivity, etc.

1-4    Mineral groups:

1-4-1    Most abundant elements:

O, Si, Al, Fe, Na, K, Ca, Mg.

1-4-2    Rock forming minerals:

  the materials that make up common rocks.
  made of Si and O, commonly called silicates.
  In silicates, Si is in the center of SiO₄ tetrahedron .
  depending on the connection of SiO₄ tetrahedra, silicates are classified as:

Structure	Representative minerals
isolated tetrahedron	olivine
single chain	pyroxene
double chain	amphibole
sheet	mica
3-d framework	feldspar

The following table lists the most important groups of silicate minerals.

Class	Arrangement of silica tetrahedra	formula of complex anion	Mineral example
Isolated tetrahedra Nesosilicates		(SiO4)4-	Olivine (Mg, Fe)2SiO4
Isolated polymerized groups Sorosilicates		(Si2O7)6-	Lawsonite CaAl2 (Si2O7) (OH)2 H2O
Cyclosilicates (3-member-ring)		(Si3O9)6-	Benitoite BaTiSi3O9
(4-member-ring)		(Si4O12)8-	Axinite Ca3Al2 (BO3) (Si4O12) OH
(6-member-ring)		(Si6O18)12-	Beryl Be3Al2 (Si6O18)
Inosilicates single chain		(SiO3)n2-	Enstatie ( a pyroxene) (Mg, Fe) (SiO3)
Inosilicates double chain		(Si4O11)n6-	Tremolite (an amphobole) Ca2Mg5 (Si4O11) (OH)2
Inosilicates triple chain		(Si3O8)n4-	Jimthompsonite (Mg, Fe)5 (Si3O8)2 (OH)2
phyllosilicates		(Si4O10)n4-	Muscovite (a mica) KAl2(Si3AlO10) (OH)2
Tectosilicates three-dimensional frame works	Too complex to be shown by a simple 2-d drawing	(SiO2)0	SiO2

1-4-3    Nonsilicates:

based on the type of anions.

This Page Was Last Modified On 07-25-02