PHYSICAL GEOLOGY: MINERALS & ROCKS Unit 2: Chapters 2 & 3

Unit Big Idea/Essential Questions  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? Earth Science Standards: 3.2, 3.6, 3.7

Key Vocabulary  Cleavage  Covalent/Ionic bonds  Fracture  Hardness  Isotope  Luster  Mineral  Radioactive Decay  Streak  Tenacity  Valence Electrons  Crystallization  Extrusive  Fossils  Igneous rock  Intrusive  Lithification  Metamorphic rock  Metamorphism  Rock Cycle  Sedimentary rock  Strata  Texture

Question of the Day  What is an element?

Bonding  Why do atoms bond?  What kind of chemical bonds can form between elements?  Ionic bonding  Covalent bonding

Isotopes and Radioactive Decay  What makes an atom an isotope?  How can radioactive decay be used in geology?  Half-life

Minerals  Characteristics of a mineral  Primary Physical Properties  Optical Properties  Crystal Habit  Mineral Strength  Density & Specific Gravity  Secondary Physical Properties  2 types of groups

Rock Forming Mineral Groups  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  Small percentage of Earth’s Crust  Prized for economic value  Most common non-silicates belong to groups  Oxides  Sulfates  Halides

Mineral Resources  Recovered for use from reserves  What is ore?

Rocks  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

Melting Crystallization Weathering/ Transport Lithification Metamorphism Heat and Pressure Uplift, weathering, erosion, deposition weathering, erosion, deposition

Igneous Rocks  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  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  Based upon texture and composition  Granitic (Felsic)  Andesitic (Intermediate)  Basaltic (Mafic)  Ultramafic

Bowen’s Reaction Series  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  Detrital  Chemical

Detrital Sedimentary Rocks  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  Formed by dissolved material in water or through aquatic organism

What can this picture tell a geologist?

Metamorphic Rocks  What does metamporphism mean?  Caused by changes in temperature, pressure, and chemical composition  Low-grade vs. High- grade metamorphism  Contact and Regional Metamorphism

Classification of Metamorphic Rocks  Texture and composition  Foilated Texture  Nonfoilated Texture