2 MINERALS Building Blocks of Rocks

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2 - MINERALSBuilding Blocks of Rocks
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WE WILL BE LOOKING AT

• Matter Atomic Structure
• Bonding
• Minerals
• Physical properties of minerals
• Major rock-forming mineral families
• Silicates - rock-forming SUPER STARS

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The Universe

• The universe is made of MATTER.
• MATTER is made of ATOMS.
• ATOMS are composed of
• PROTONS
• NEUTRONS
• ELECTRONS

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Structure of an Atom
Protons /1 Neutrons 0/1 Electrons -/0
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ATOMIC INFO

• ATOMIC NUMBER - the number of protons in the
  nucleus (I.D.s the element)
• ATOMIC MASS (WEIGHT) - total number of protons
  neutrons in the nucleus - explains ISOTOPES.
• IONS - a charged particle (atom) which means that
  there are too many OR too few electrons - CATIONS
  ANIONS.

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BONDING (electrons job) 4 kinds of bonds

• IONIC - electrical charge
• COVALENT - sharing
• METALLIC - inner shell covalent bond
• INTERMOLECULAR - Van der Waals

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IONIC BONDING - electrical
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Covalent Bonding in Diamond
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Covalent Bonds in Water
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Carbon Atoms in Graphite
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MINERALS - Rock Builders

• NATURALLY FORMED
• INORGANIC
• CRYSTALLINE SOLID
• DIAGNOSTIC CHEMICAL COMPOSITION

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Galena (PbS)
CRYSTALLINE SOLID
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Atomic Structure of Galena
Sulfur
Lead
DIAGNOSTIC CHEMICAL COMPOSITION
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WHAT FACTORS DETERMINE WHAT MINERAL WILL FORM?

• WHAT ELEMENTS ARE AVAILABLE
• ABUNDANCE OF EACH ELEMENT
• SIZE CHARGE OF EACH ATOM
• ENVIRONMENT - SPACE, PRESSURE, TEMPERATURE

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Ionic Radii charge of some geologically
important ions allows ionicsubstitution
SOLID SOLUTION
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Irregular Intergrowth of Quartz
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BandedAgate
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Identify Minerals by Their Physical Properties

• Crystal Habit
• Cleavage Fracture
• Striations
• Hardness

• Specific Gravity
• Color
• Streak
• Luster
• Acid Test (ct)

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Constancy of Interfacial and Angles in Quartz
Crystal Form - Constancy of Interfacial Angles
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Cleavage
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StriationsPyrite (Fools Gold)FeS)
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Examples
MOHS HARDNESS SCALE
Brian Skinner
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The Different Colors of Corundum
Ruby
Sapphire
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Streak - color of rock power
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GALENA (Pb S) - Identified by crystal habit
luster specific gravity hardness
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Acid Test - a chemical test
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Average Composition of the Continental Crust
O
O
Si
Weight Percent
Volume Percent
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COMMON ROCK-FORMINGMINERAL FAMILIES

• NATIVE ELEMENTS - GOLD, COPPER
• HALIDES - PRECIPITATES
• OXIDES - 1 METAL OXYGEN
• SULFIDES - 1 METAL SULFUR
• SULFATES - (SO4)2-
• CARBONATES - (CO3)2-
• SILICATES - SUPER STARS!!!

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Various Views of the Silica Tetrahedron
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One view of the Silica Tetrahedron - - silicate
BUILDING BLOCK
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Linking Silicate Tetrahedra
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About Silicates

• There are 2 families of silicates
• FERROMAGNESIAN SILICATES - Fe/Mg -gt MAFIC
  MINERALS
• NONFERROMAGNESIAN or ALUMINO- SILICATES -gt FELSIC
  MINERALS

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Important minerals
Olivine Si, O, Fe, Mg Pyroxene Si, O, Fe, Mg,
Ca Amphibole Si, O, Ca, Mg, Fe, OH Biotite
Mica Si, O, Al, Fe, Mg, OH Muscovite Mica Si, O,
Al, K, OH Feldspars Si, O, Al, Ca, Na,
K Quatrz Si, O Carbonates C, Ca, Mg,
O Evaporites K, Cl, Ca, S
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Isolated Tetrahedra Silcate (example olivine
(Mg,Fe)2SiO4)
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Comparison of Cleavage and Crystal Faces
Pyroxene
Amphibole
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Framework (example quartz)
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Atomic Structure of Micas
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Clay a sheet silicate
SHEET SILICATES
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Muscovite Biotite Mica
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GREEN FELDSPAR
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Polished Section
1 cm
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Thin Section
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Thin section under ordinary light
Magnetite
Feldspar
Mica
Quartz
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Thin section under polarized light