Minerals
Goals
1) To understand what minerals are and how
they are put together; 2) To examine some
important ore minerals; and 3) To examine
some of the most common rock forming
minerals
To earn the name mineral
• Naturally occurring and inorganic solid
• Characteristic chemical composition
• Regularly repeating internal crystalline
structure
Silicon +
2 oxygen
SiO2
Who has earned the name
• Ice (H2O) is a mineral,
liquid water is not: Why?
• Quartz (SiO2) is a mineral,
glass is not: Why?
Atoms and atomic bonds
Why are diamonds hard and pencil “leads”
(graphite) soft?
Diamond
Graphite
Diamond Saw
Atoms
• Nuclease of Protons (+) and Neutrons (0)
• Cloud of orbiting Electrons (-)
Electrons (e-)
Electrons are divided into groups called orbitals
• Outer orbital of Hydrogen and Helium can hold 2
electrons
• Outer orbitals of all other atoms can hold 8 electrons
2 e8 e-
Orbitals
Chemical bonds
All atoms are greedy little buggers—They all
want a full outer orbital, and they’ll bond
with almost anyone to get it!
Chemical bonds allow atoms to exchange or
share electrons
Methane: Carbon
bonded to four
hydrogen atoms
Ionic bonds
One atom’s trash is another atom’s treasure
Cations: throw away their outer electrons—net
positive charge
Anions: pickup cast-off electrons—net negative
charge
Salt combines
sodium cation
(Na+) with chlorine
anion (Cl-)
Covalent bonds
Atomic monogamy: Atoms share outer
electrons with a few partners.
quartz contains covalent bonds
Strongest type of bond
In methane carbon
shares one outer ewith 4 hydrogen atoms
Metallic bonds
Atoms have a giant electron orgy
Nuclei float in a sea of shared electrons
Intermolecular bonds
Bonded atoms do a little sharing on the side
Weakest type of bond!
Some molecules
have a weakly
positive side and a
weakly negative side
Water
Think-pair-share activity
1. We know that diamonds are one of the
hardest substances known to man and
graphite is one of the softest. Both are
made entirely of carbon
2. Come up with an explanation for this.
3. Compare, discuss, and refine your idea
with one or two of your neighbors.
4. Write up your results and pass them in.
Graphite
Diamond
Different types of bonds
Crystalline structure
• Geometric
arrangement of
atoms
• Dictated by the types
of elements present
and the pressure and
temperature
conditions
Graphite
Diamond
Same chemical
composition, different
pressure and temp.
Important ore minerals
Ore: metal-bearing mineral or rock that can be
mined for a profit
Jet engine—We need iron (steel), titanium, and
aluminum... where do we get these metals?
Oxide minerals metal atoms covalently
bonded to oxygen
Hematite and magnetite — Iron oxides
• Our primary source of iron
• Found in banded iron formations (BIF’s)
• Most BIF’s 2–3 b.y. old
Rutile — Titanium oxide
• One of our main sources of titanium
• Often concentrated in beach sands
Bauxite — Aluminum bonded with oxygen
and hydrogen (aluminum hydroxide)
• The main source of aluminum
• Forms due to extreme weathering in tropical
soils
Iron (steel), titanium, and aluminum in this jet
engine come from:
• 2.5 b.y. old rocks deposited in the deep ocean
• Beach sand
• Tropical soil
No puppies were harmed in the
making of this jet engine
Sulfide minerals metal atoms ionically
bonded to sulfur
Pyrite — Iron sulfide
• Common in coal beds and ore deposits
• Source of much acid mine drainage
Chalcopyrite — Copper-iron sulfide
• Often found in volcanic rocks found at
convergent margins
• Primary source of copper
Rock forming minerals
Minerals that make up most of the earth
Most common elements in the crust
1. Oxygen
2. Silicon
3. Aluminum
4. Iron
5. Calcium
6. Magnesium
7. Sodium
8. Potassium
Silicate minerals
Silicate minerals—built around pyramid-shaped
combinations of silicon and oxygen atoms called
silica tetrahedrons
Silica tetrahedron: Silicon atom
covalently bonded to 4 oxygen
atoms
Silicate minerals fall into two categories:
Mafic minerals—silica tetrahedrons bonded to
iron, magnesium, and calcium
• Generally dark colored
• More dense
• Common in oceanic lithosphere
Felsic minerals—silica tetrahedrons bonded to
aluminum, potassium, and sodium
• Generally light colored
• Less dense
• Common in continental
lithosphere
Mafic minerals
Olivine—single silica tetrahedrons covalently
bonded to magnesium or iron
• Makes up 90% of the mantle
Mafic minerals
Pyroxene—chain of silica tetrahedrons bonded to
magnesium, iron, and calcium
Mafic minerals
Amphibole—double chain of silica tetrahedrons
bonded to magnesium, iron, and calcium
Mafic minerals
Biotite—sheets of silica tetrahedrons bonded to
magnesium, iron, and potassium
Felsic minerals
Muscovite—sheets of silica tetrahedrons bonded
to aluminum and potassium
Felsic minerals
Potassium feldspar—network of silica tetrahedrons
bonded to potassium and aluminum
Felsic minerals
Quartz—network of silica tetrahedrons
Most
common
mineral
in crust
Silicon dioxide
Plagioclase feldspar minerals
Plagioclase feldspars—network of silica
tetrahedrons bonded to calcium (mafic) and/or
sodium (felsic)
• Calcium plagioclase
feldspar = mafic
• Sodium plagioclase
feldspar = felsic
Mafic
Calcium
plagioclase feldspar
= black lab puppy
Sodium+Calcium
plagioclase feldspar
= chocolate lab
puppy
Sodium plagioclase
feldspar = yellow lab
puppy
Felsic
Feldspar
minerals are like
retriever
puppies
Potassium
feldspar = golden
retriever puppy
Other important mineral groups
Clay minerals—Sheet silicates that form due to
chemical alteration at the Earth’s surface
• Very common in soils
• Used to make paper, ceramics, and bricks
Other important mineral groups
Carbonate minerals—Combine carbonate ions
(CO32-) with calcium to make Calcite and
calcium and magnesium to make dolomite
 Extremely important to global carbon dioxide
cycles