Rocks and Minerals
Minerals (by def)
- naturally occurring
- inorganic
- solid
- definite chemical composition
- a crystal structure
Rocks and Minerals
1. Naturally Occurring
mineral: quartz pyrite
Not mineral: cement, steel
Rocks and Minerals
2. Inorganic
- does not come from
anything living
Ex: coal, pearls
Amber (not minerals)
Definite Chemical Composition
Name of
Mineral
Chemical
Formula
Chemical
Name
Elements and
no of atoms
Halite
NaCl
Sodium
Chloride
1 sodium
1 chlorine
Quartz
SiO2
Silicon Dioxide
1silicon
2 oxygen
Pyrite
FeS2
Iron Sulfide
1 Iron
2 sulfur
Hematite
Fe2O3
Iron Oxide
2 iron
3 oxygen
Magnetite
Fe3O4
Iron Oxide
3 iron
4 oxygen
Calcite
CaCO3
Calcium
Carbonate
1 Calcium
1 Carbon
3 Oxygen
Graphite
C
Carbon
1 Carbon
Diamond
C
Carbon
1 Carbon
Rocks and Minerals
4. Solids:
Have definite size/volume
and a definite shape
Ex: oil, lava, magma
Rocks and Minerals
5 Crystal Shape:
Atoms arranged in repeating
patterns.
Mineral Formation
1. From Cooling
lava/Magma
2. When water evaporates,
dissolved minerals remain
behind
(precipitate out)
Identifying Minerals
Identified by Physical and
Chemical properties
Physical: Color, Streak, Luster,
Hardness, Density
Chemical: reactivity, special
properties
Physical Properties
1. Color: (vary due to impurities)
a. Some minerals have only one color
- olivine: green
- sulfur: yellow
b. Others have many colors
- quartz: clear, pink, purple, white, smoky
- hematite: black, grey red-brown, dark red
Physical Properties
2. Streak: color of powder when
mineral is rubbed on a streak plate
- Streak never changes
Ex: Hematite: color varies
Dark red, reddish brown, grey
Streak: always reddish brown
Physical Properties
3. Luster: the way a mineral shines
or reflects light from its surface
2 types
Metallic: shines/reflects light like a
metal (quarter)
Nonmetallic: pearly, glassy, dull,
waxy, brilliant
Mineral
Hardness
4. A measure of how
easily a mineral can be
scratched
1 softest mineral
10 hardest mineral
A mineral with a
hardness 4 can scratch
itself and anything
below
Number
Name of
mineral
1
talc
2
gypsum
3
calcite
4
fluorite
5
apatite
6
feldspar
7
quartz
8
topaz
9
corundum
10
diamond
Mineral Hardness/Common
Objects
2.5 Fingernail
3.5 Copper Penny
4.5 Iron Nail
5.5 Glass Plate
6.5 Steel File
7 Streak Plate
Mineral Properties
5. Cleavage and Fracture
a. Cleavage: when a mineral
splits along smooth flat
surfaces.
- Ex: Mica:
one direction
Mineral Properties
Ex: Galena: three directions
Determined by internal
structure of mineral bonds
between the atoms
Mineral Properties: Cleavage
Cleavage does not = Crystal Shape
Crystal way mineral grows
Cleavage way
mineral breaks
Mineral Properties
Fracture: mineral breaks unevenly
curved or irregular pieces
rough/jagged surfaces
Density or Heft
6. Density: How closely the
atoms are packed into a given
space.
Different minerals of the same
size have different densities
and feel heavier or lighter
Chemical Properties
Calcite: reacts with HCL. It forms
bubbles of carbon dioxide gas
CaCO3 + 2HCl -> CaCl2 + H2O + CO2
Special Properties
Lodestone, a form of the mineral
magnetite is naturally magnetic
Calcite, shows double refraction
Pitchblende: is radioactive
Uses of Minerals
A. Ore: A mineral that contains
Metals and nonmetals that can be
removed in usable amounts for a
profit.
1. Metals: elements shiny surfaces
conduct heat and electricity
Metals
1. Iron: hematite: Fe2O3
Magnetite: Fe3O4
2. Aluminum: bauxite: Al(OH)3
3. Copper: Chalcopyrite: CuFeS2
malachite:Cu2CO3(OH)2
Metals
4. Silver: Argenite: AgS2
5. Gold: Gold: Au
6. Mercury: cinnabar : HgS
Alloy
A mixture of two or more metals or a
mixture of metals and nonmetals
1. Tin + Copper -> bronze
2. Zinc + Copper -> brass
3. Iron + chromium + limestone -> steel
4. Tin + lead -> pewter
Nonmetals
Elements dull surfaces, poor
conductors of heat, electricity
1. Halite: Salt: NaCL
2. Gypsum: drywall
3. Sulfur: matches
4. Talc: talcum powder
5. Graphite: pencils
Gems
Minerals with desirable qualities
hardness, color, luster, rare,
durable
Precious stones: diamonds, rubies
sapphires
Semiprecious: amethyst, garnet topaz
Gems not minerals: pearls