MINERALS
Chemical
composition of the
Crust





Oxygen most abundant- 46.6%
Followed by silicon and
aluminum
Iron, Calcium, Sodium,
Potassium, Magnesium
The most common minerals
will be composed mostly of
these elements
Silica & silicates
MINERAL vs. ROCK

ROCK
 An
aggregate of one or more MINERALS
(usually- coal, organic)

MINERAL
 Solid
 Crystalline-
orderly arrangement of atoms
 Naturally occurring
 Inorganic
 Definite chemical composition
 e.g.
SiO2 for quartz; KAlSi3O8 for
feldspar
Atom & Elements

Atoms
 Neutral
 Nucleus
 Proton,


Electron
Ions
 Electrical

neutron
Charge
Molecule- e.g. water molecule
Chemical activity

Stable atoms want
 positive
& negative charges balanced
 electron shells full


Ions- positive (Cations) and negative (Anions)
Bonding
 Ionic
 Covalent
 Metallic
 Van
der Waal’s
Element

Atomic number
 Number

of PROTONS
Isotope
 Differing
number of
NEUTRONS

Atomic weight
 Mass
of PROTONS and
NEUTRONS
Crystallinity



3 dimensional orderliness of atoms
Silicon-oxygen tetrahedron
Silicate structures
 Single-
e.g. olivine
 Chain
 Single
chain- pyroxene
 Double chain- amphibole
 Sheet-
e.g. mica, clay
 Framework- e.g. quartz, feldspar
MINERALS



Crystalline solids
Natural and Inorganic Substances
Definite chemical composition
 Can
be written as a chemical
formula
 Solid solution (within a range)
Important Minerals


Quartz (most abundant)
FELDSPAR Group
 Potassium
Feldspar - Orthoclase
 Plagioclase Feldspar
 Sodium
(Na) Albite
 Calcium (Ca) Anorthosite
Important Minerals



PYROXENE Group- Augite most
common
AMPHIBOLE Group- Hornblende
most common
MICA Group- Si + O in sheets
 Biotite
 Muscovite

CALCITE- CaCO3
Properties of Minerals

Color
 Not
always reliable (Olivine, green; Flourite,
yellow, purple, green…)
 Ferromagnesian minerals green or black


Streak- powdered form
Luster- reflectance of light
 Metallic
 Nonmetallic
 Vitreous
 Earthy
or Glassy
Properties of
Minerals


Hardness- resistance to scratching
Moh’s Hardness Scale
 Fingernail
= 2.5
 Penny = 3.5
 Knife/Glass = 5.5
 Streak Plate= 6.5

Cleavage
Properties of
Minerals
 Quality
(poor, good, perfect)
 Number of directions
 One-
e.g. Mica
 Two at right angles- e.g. Feldspar, Pyroxene
 Two not at right angles- e.g. Amphibole
 Three at right angles (cubic)- e.g. Halite
 Three not at right angles (rhombohedral)- e.g.
calcite
 Four (Flourite) or six (Sphalerite)- not common

Properties of
Minerals
Fracture
 Absence
of cleavage
 Irregular fracture
 Conchoidal fracture- Quartz

Density
 Specific

Gravity
Some unusual properties
 Striations,
refraction
Magnetism, Taste, Odor, Double
Chemical tests

Reaction with HCl
 Calcite
effervesces
Mineral Groups







Silicates
Carbonates
Oxides
Sulfides
Sulfates
Native Elements
Halides
Silicates






Quartz
Feldspar
 Plagioclase
 Orthoclase
Micas
 Muscovite
 Biotite
Amphibole (Hornblende)
Pyroxene (Augite)
Olivine
Carbonates



Calcite (calcium carbonate)
Dolomite (calcium-magnesium
carbonate)
Both are used as Portland Cement
Oxides

Hematite (iron oxide)
 Iron

Magnetite
 Iron

ore, pigment
ore
Corundum (aluminum oxide)
 Sapphire,
 Abrasive
ruby (gemstone)
Sulfides

Galena (Lead sulfide)
 Lead

Sphalerite Zinc sulfide)
 Zinc

ore
ore
Pyrite (Iron sulfide)
 Sulfuric

acid
Chalcopyrite (Copper Iron sulfide)
 Copper
ore
Sulfates



Gypsum
Anhydrite
Both use in plaster
Native Elements







Gold- trade, instruments
Silver- photography, conductors
Copper- electrical
Platinum- catalysts
Sulfur- chemicals, pharmaceuticals
Diamond- carbon
 Gemstone, abrasive
Graphite- carbon
 Lubricant, pencils
Minerals as Resources




Reserves: Minerals that can be
extracted at a profit under current
economic and technological
conditions
Ores: metallic minerals
Industrial Rocks or Minerals: non
metallic minerals (phosphate)
Aggregates: crushed rock
ROCK CYCLE


Equilibrium
Interrelationships between
 igneous
rocks
 sediment
 sedimentary rocks
 metamorphic rocks
 weathering and erosion