PHYSICAL GEOLOGY:
MINERALS & ROCKS
Unit 2: Chapters 2 & 3
Unit Big Idea/Essential Questions
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Earth is comprised up of elements which form
minerals and rocks.
Essential Questions
 How
does the Rock Cycle work?
 Why is the type of bond formed between elements
important?
 How can isotopes be used in radioactive dating?
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Earth Science Standards: 3.2, 3.6, 3.7
Key Vocabulary
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Cleavage
Covalent/Ionic bonds
Fracture
Hardness
Isotope
Luster
Mineral
Radioactive Decay
Streak
Tenacity
Valence Electrons
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Crystallization
Extrusive
Fossils
Igneous rock
Intrusive
Lithification
Metamorphic rock
Metamorphism
Rock Cycle
Sedimentary rock
Strata
Texture
Question of the Day
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What is an element?
Bonding
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Why do atoms bond?
What kind of chemical bonds can form between
elements?
 Ionic
bonding
 Covalent bonding
Isotopes and Radioactive Decay
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What makes an atom an isotope?
How can radioactive decay be used in geology?
 Half-life
Minerals
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Characteristics of a mineral
Primary Physical Properties
 Optical
Properties
 Crystal Habit
 Mineral Strength
 Density & Specific Gravity
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Secondary Physical Properties
2 types of groups
Rock Forming Mineral Groups
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Silicates
8
elements (O, Si, Al, Fe, Ca, Na, K, Mg)
 Tetrahedron building block in chains, sheets, 3D
 Fe, Mg, K, Na, Ca binds to larger silicate structures
 Structure and Chemical composition indicates conditions
under which mineral group formed
 Types of Silicates: olivine, pyroxene, amphibole, micas,
feldspars, quartz
Non-silicates
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Small percentage of Earth’s Crust
Prized for economic value
Most common non-silicates belong to groups
 Oxides
 Sulfates
 Halides
Mineral Resources
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Recovered for use from reserves
What is ore?
Rocks
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What is a rock?
Comprised up of mineral or mineral-like matter
Contains clues about environment in which it formed
3 groups based upon origin
 Igneous
 Sedimentary
 Metamorphic
Heat and Pressure
Igneous Rocks
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Ignis=fire So where do these rocks come from?
Extrusive Igneous Rocks vs. Intrusive Igneous Rocks
Crystallization
 Rate of cooling, composition, and dissolved gases
influence crystal size
Texture
 Size, shape, arrangement of crystals
 Fine-grained, Coarse-grained, Porphyritic, Glassy
Igneous Composition
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Silica- most abundant in magma
Al, Ca, Na, K, Mg, Fe are also found in
magma
Dark silicates rich in Fe and/or Mg,
low silica
Light silicates rich in K, Na, Ca, high
silica
Classification of Igneous Rocks
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Based upon texture and composition
Granitic (Felsic)
Andesitic (Intermediate)
Basaltic (Mafic)
Ultramafic
Bowen’s Reaction Series
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Relation between magma and the minerals that
form during cooling
Sedimentary Rocks
Sedimentum=settling So how do these
rocks form?
 Lithification of sediments via compaction
and cementation
 Reveals many details of Earth’s history
 2 groups
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 Detrital
 Chemical
Detrital Sedimentary Rocks
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Particle size is used to distinguish between
rocks
Coarse (gravel-like)
Medium (sand-like)
Fine (silt/mud-like)
Very Fine (mud-like)
Chemical Sedimentary Rock
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Formed by dissolved material in water or through
aquatic organism
What can this picture tell a geologist?
Metamorphic Rocks
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What does
metamporphism mean?
Caused by changes in
temperature, pressure,
and chemical composition
 Low-grade
vs. Highgrade metamorphism
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Contact and Regional
Metamorphism
Classification of Metamorphic Rocks
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Texture and composition
 Foilated
Texture
 Nonfoilated Texture