How to identify a mineral 3

Minerals


Take-Away Points
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Chemical elements form in stars
Atoms bond by sharing electrons
Minerals are classified by their chemistry
Minerals can be identified by their
physical properties = atomic structure
5. Silicates are the most important mineral
group
6. Crystals are determined by mathematical
rules called symmetry


Composition of the Sun

1. Chemical elements form in stars


Composition of the Sun
• Abundance of Light
Elements
• Rarity of Lithium,
Beryllium, Boron
• Preference for Even

Numbers
• Abundance peak at
Iron, trailing off after
1. Chemical elements form in stars


How Elements Form in Stars
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Sun: 4 H  He
He + particle  Mass 5 – Unstable
He + He  Mass 8 – Unstable
He + He + He  C
Add more He to make heavier elements
End of the line is iron for energy production
Atoms beyond Iron made in massive stars
1. Chemical elements form in stars


What are Planets Made of?
• Same material as Sun
• Minus the elements that remain mostly in
gases
• We find this pattern in a certain class of

meteorites

1. Chemical elements form in stars


Chondrites

1. Chemical elements form in stars


The Earth’s Crust looks Very
Different

1. Chemical elements form in stars


Composition of the Crust

1. Chemical elements form in stars


Minerals are the Chemicals that
make up the Earth
• Naturally Occurring
• Inorganic
• Chemical Compounds
• About 5000 Known
• 200 Common
• 20 Rock-Forming

Atomic Bonding
1. IONS

2. Atoms bond by sharing electrons


Atomic Bonding
2. Electrical Neutrality
• (+) and (-) Cancel Out
3. Bonding (Satisfy 1 & 2)
• Ionic (NaCl)
• Covalent (O2)
• Metallic (Cu, Al, Fe)
• Hydrogen (in water)
2. Atoms bond by sharing electrons


Ionic and Covalent Bonding

2. Atoms bond by sharing electrons


Metallic Bonding

2. Atoms bond by sharing electrons


Hydrogen Bonding

2. Atoms bond by sharing electrons


Summary of Bonding
• Ionic bonding holds rocks and minerals
together
• Covalent bonding holds people and other
organisms together
• Metallic bonding holds civilization together
• Hydrogen bonding gives water its heatretaining and solvent properties
2. Atoms bond by sharing electrons


4. Lattices
• Atoms in crystals form a repeating pattern
called a Lattice

2. Atoms bond by sharing electrons


5. Complex Anions (Radicals)
• Many minerals contain groups of atoms
that behave as single units

2. Atoms bond by sharing electrons


NAMING MINERALS
COLOR
• Glauconite (Greek: Glaucos = Blue-green)

OTHER PROPERTIES, USES
• Magnetite
COMPONENTS
• Chromite
PLACES
• Muscovite (Moscow)
PEOPLE
• Biotite


Chemicals (and Minerals) Are
Classified by their Anions

3. Minerals are classified by their chemistry


For Example: Iron Compounds
Have Little in Common
• Fe: Gray, Metallic
• FeCl2: Light Green, Water Soluble
• FeSO4: Light Green, Water Soluble
• FeCO3: Brown, Fizzes in Acid
• FeS2: Dense, Brittle, Metallic, Cubic Crystals

3. Minerals are classified by their chemistry


On the Other Hand, Sulfides
have Many Properties in
Common

• FeS2

• CuFeS2
• PbS
• ZnS2
All are Dense, Brittle, Metallic, have Cubic
Crystals
3. Minerals are classified by their chemistry


Identifying
Minerals

4. Minerals can be identified by their physical properties


Identifying Minerals
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Color: very variable, complex causes
Hardness: strength of atomic bonds
Density: mass and spacing of atoms
Luster: how electrons interact with light
Cleavage: weak atomic planes

Crystal Form: extremely useful but not for
beginners
• Other properties distinctive at times
4. Minerals can be identified by their physical properties = atomic structure


Color
• Sometimes Distinctive
• Often Unreliable
• Affected By:
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Chemical Impurities
Surface Coating
Grain Size
Weathering

4. Minerals can be identified by their physical properties = atomic structure