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What Is a Mineral?
• A mineral is a solid, naturally occurring
substance that has a specific chemical
composition and a highly ordered internal
(crystalline) structure.
What is a Rock?
• A solid, cohesive aggregate of grains of one or
more minerals
CRYSTAL - A mineral grain displaying the characteristics of its
atomic structure.
- almost 4000 different kinds of minerals
- differences result from the different elements used and the
ways they are bonded
Chemistry Review :
An ELEMENT is determined by the number of PROTONS (+).
IONS - Atoms where the number of ELECTRONS (-) have been added or
subtracted.
ISOTOPES - Atoms where the number of NEUTRONS have been added or
subtracted.
The Structure of
the Atom
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Atomic number
= Number of protons
 Elements
Atomic Mass
= Number of protons + neutrons
 Isotopes
Periodic Table of the Elements
The Structure of
the Atom
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Atomic number
= Number of protons
 Elements
Atomic mass
= Number of protons + neutrons
 Isotopes
Chemical Bonds – Forces that keep atoms together
Bonds are strong when the electron orbitals (“shells”) are complete.
# of electrons in
Orbital
Total # of
electrons
2
2
8
10
8
18
18
36
18
54
Etc.
The Structure of the Atom
• The size of atom is determined by electron cloud
of the ION
Changing Model of the Atom
How Atoms Bond
Types of bonding
• Ionic
• Covalent
• Metallic
• Intermolecular
Figure 2-7
Atoms gain or lose electrons, becoming negatively charged
ions or positively charged ions that attract each other.
How Atoms Bond
IONIC BOND
Ex: Halite (salt)
Q: Which is Na? Cl?
How Atoms Bond
Types of bonding
• Ionic
• Covalent
• Metallic
• Intermolecular
Sharing of electrons
between similar atoms
– strongest type of
bond
How Atoms Bond
Types of bonding
• Ionic
• Covalent
• Metallic
• Intermolecular
Electrons move continually among close-packed nuclei.
How Atoms Bond
Types of bonding
• Ionic
• Covalent
• Metallic
• Intermolecular
Weak attraction between molecules due to an uneven
distribution of electrons – van der Waals bond.
Mineral Stability
• Ion charges must sum to ZERO
• Ion sizes must be compatible (electron cloud)
Mineral Stability
Mineral Stability
Mineral Stability
• Temperature and pressure play defining roles in
establishing stability of mineral
Mineral Stability
• Why are there different
forms of ice at different
temperatures and
pressures?
Mineral Stability
• Why are there different
forms of ice at different
temperatures and
pressures?
• Because the ion sizes
change, relative to each
other, at different T & P,
so the ideal packing
changes.
Mineral Stability
• How might
stishovite occur
naturally?
Mineral Stability
• How might
stishovite occur
naturally?
• Meteorites!
Minerals are clues to the past!
Mineral Stability
• How might
stishovite occur
naturally?
• Meteorites!
• Why are they
still at the
surface?
Minerals are clues to the past!
Mineral Stability
• How might
stishovite occur
naturally?
• Meteorites!
• Why are they
still at the
surface?
• Metastability
(too cold to
change back)
Minerals are clues to the past!
Diamonds only
form naturally
more than about
150 km beneath
the surface.
They are
unstable at the
surface – they
will burn in a fire.
Mineral Composition
Rock-Forming Minerals
A. Silicates
– e.g., quartz (SiO2), orthoclase (KAlSi3O8)
B. Non-silicate mineral groups
– Carbonates - e.g., calcite (CaCO3), dolomite (MgCa(CO3)2)
– Oxides - e.g., hematite (Fe2O3), magnetite (Fe3O4)
– Sulfides - e.g., pyrite (FeS2), galena (PbS)
– Sulfates - e.g., gypsum (CaSO4)
– Natives - e.g., gold (Au), silver (Ag), diamond (C), platinum (Pt)
Silicates
Make up 90% by weight of Earth’s crust
• Si and O are the two
most abundant
elements in the Earth’s
crust (differentiation).
• Small silicon ions fit
snugly in the niches
among large closely
packed oxygen ions.
Silica Tetrahedron:
Slightly changing the different elements that combine with silica greatly
changes the mineral that results, or the characteristics of the mineral.
Ex/ Different forms of quartz
Types of Silicates
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Independent tetrahedra
Single chains
Double chains
Sheets
Framework
Example:
Olivine
Types of Silicates
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Independent tetrahedra
Single chains
Double chains
Sheets
Framework
Example:
Pyroxene
Types of Silicates
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Independent tetrahedra
Single chains
Double chains
Sheets
Framework
Example:
Amphibole
Types of Silicates
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Independent tetrahedra
Single chains
Double chains
Sheets
Framework
Example:
Muscovite
Types of Silicates
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Independent tetrahedra
Single chains
Double chains
Sheets
Framework
Example:
Quartz
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
A mineral’s chemical
composition and crystal
structure give it a unique
combination of chemical
and physical properties we
can use to identify it.
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
Figure 2-20
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
Stibnite
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
Figure 20-22
Identifying Minerals
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Color
Luster
Streak
Hardness
Cleavage
Fracture
Smell
Taste
Crystal form
Density
Laboratory
tests
EPS Electron Microprobe
Fluorescent lighting spectrum peaks
Fluorescent lighting spectrum peaks
Peak number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Wavelength of peak (nm)
405.4
436.6
487.7
542.4
546.5
577.7
580.2
584.0
587.6
593.4
599.7
611.6
625.7
631.1
650.8
662.6
687.7
693.7
707 and 709
712.3
760.0
811.0
Species producing peak
mercury
mercury
terbium
terbium
mercury
terbium
mercury or terbium
terbium from Tb3+ or europium in Eu+3
europium in Eu+3
europium in Eu+3
europium in Eu+3
europium in Eu+3
terbium from Tb3+
europium in Eu+3
europium in Eu+3
europium in Eu+3
europium in Eu+3
europium in Eu+3
europium in Eu+3
europium in Eu+3
argon
argon
Visit the EPS Mineral Collection