Download Minerals - Paul J. Goodenough

 Rock – an aggregate of minerals (mixture
of minerals).
 Mineral – naturally occurring, inorganic,
crystalline solids, with a definite
chemical composition.
All minerals are rocks, but not all
rocks are minerals!
Granite
(rock)
mixture of:
Feldspar
(mineral)
Biotite
(mineral)
Quartz
(mineral)
1. Crystal Form


External expression of a mineral’s
internal orderly arrangement of
atoms.
Size of the crystal is based on time
& available space.
Crystal Shapes:
Cubic
Hexagonal
Orthorhombic
Monoclinic
Tetragonal
Triclinic
2. Luster


Appearance /quality of light
reflected from the surface of a
mineral.
Metallic vs. Nonmetallic.
Choosing the Luster:
Luster
Shiny like a metal?
Yes
Metallic
No
Nonmetallic
What kind of nonmetallic?
Vitreous
(glassy)
Pearly
Silky
Resinous
Earthy
3. Color



Outer appearance.
Unreliable property.
A mineral may have
several color varieties.
4. Streak


Color of the mineral in a
powdered form.
Obtained by rubbing the mineral
across a streak plate.
5. Hardness

Resistance to abrasion or
scratching.
Mohs’ Scale
Softest
Hardest
How to test a mineral’s hardness
1. Start by moving an unknown sample across a sample
with a hardness of 1.
2. If the unknown scratches the known sample, then it is
harder….so keep testing the others until it doesn’t
scratch it.
3. If it doesn’t scratch it, then it is softer than the known
sample so it is lower on the scale.
4. If they scratch each other, they are the same hardness.
6. Cleavage



Tendency for a mineral to break
along planes of weak bonding.
Smooth surfaces.
Not to be confused with crystals.
7. Fracture



Opposite of cleavage.
Conchoidal fracture = curved edges.
Fibrous fracture = splinters/fibers.
8. Specific Gravity



Comparison between the weight of a
mineral to the weight of an equal
volume of water.
Comparison of densities.
Written as the number of times
heavier/lighter than water.
9. Other Properties







Taste
Elasticity
Malleability
Texture
Magnetism
Double Refraction
Reaction to acids (HCl)
 8 elements make up 98% of the Earth’s crust (by
weight).
O
 Si
 Al
 Fe
 Ca
 Na
K
 Mg
 Silicate Group
 Minerals made of O and Si.
 ¾ of the minerals in the continental crust are silicates.
 Silicon-oxygen tetrahedron (1 silicon to 4 oxygen) then
bonded to another element(s).
 EXAMPLES:
 Quartz, Feldspars, Micas
 Carbonates Group
 Minerals made of CO3 bonded with other elements.
 EXAMPLES:
 Calcite & Dolomite
 Halides Group
 Minerals made with members of the halogen family.
 Formed through evaporation.
 EXAMPLES:
 Halite & Fluorite
 Sulfates Group
 Minerals made of SO4 bonded with other elements.
 EXAMPLES:
 Gypsum
 Oxides Group
 Minerals made with Oxygen bonded with other
elements.
 EXAMPLES:
 Hematite & Ice
 Native Elements Group
 Minerals that are pure elements (usually metals).
 EXAMPLES:
 Copper, Diamond, Graphite
 Sulfides Group
 Minerals made with Sulfur bonded with other elements.
 EXAMPLES:
 Pyrite
 Ores – useful metallic minerals that are mined at a
profit.
 EXAMPLES: Hematite (Iron), Sphalerite (Zinc), Galena
(Lead), Cinnabar (Mercury).
 Industrial rocks & minerals – useful nonmetallic
minerals that are mined at a profit.
 EXAMPLES: Fluorite, Sulfur, Halite (salt)
 The amount of a mineral in a deposit must be
concentrated several times it’s crustal percentage to be
considered profitable.
 Gemstones – Crystal forms of minerals that posses
beauty of such quality that command
a price when cut & polished.
 Precious gems – have beauty, durability, size, and rarity.
 Diamond
 Emerald (Beryl)
 Ruby (Corundum)
 Sapphire (Corundum)
 Semiprecious gems – only have one or two of the
qualities of precious gems.
 EXAMPLES: Amethyst , Topaz, Garnet, Zircon
 Non-mineral gems – stones that have value, but are not
minerals.
 EXAMPLES: Coral, Amber, Pearl
 Precious Metals – metallic minerals that have high
value.
 EXAMPLES: Gold, Silver, Platinum