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Unit II Rocks and Minerals
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Earth’s Interior Our Earth consists of four main layers
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Earth’s Interior Inner Core- 760 mile radius, consisting of solid iron and nickel and also reaching temperatures close to the Sun’s surface Outer Core- transition layer that still consists iron and nickel yet is a thick liquid layer
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Earth’s Interior Mantle- Largest portion of the interior and has the most viscosity (thinnest liquid) Crust- 3 to 40 miles thick and is often divided into two separate layers Continental- Old cratons in which we live and has an average density of 2.7 g/cm^3 Oceanic- Newly created crust along the ocean floor and has an average density of 3.0 g/cm^3
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Composition of Earth’s Crust There are 8 elements that make up 99% of the Earth’s Crust 1.Oxygen (47%) 2.Silicon (28%) 3.Aluminum (8%) 4.Iron (5%) 5. Calcium (3%) 6. Sodium (3%) 7.Potassium (3%) 8.Magnesium (2%)
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Minerals Minerals- naturally occurring solid; a chemical substance that is formed through geological processes and that has specific characteristics
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Minerals Characteristics of Minerals 1.Occur naturally 2.Are solids 3.Definite chemical composition 4.Atoms are arranged in definite pattern 5.Are inorganic
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Minerals Is ice considered a mineral, why or why not????
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Minerals 1.Occur naturally- as snow, sleet or rain 2.Are solids- Check 3.Definite chemical composition- 2 Hydrogen's and 1 Oxygen (H 2 O) 4.Atoms are arranged in definite pattern- Hexagonal symmetry
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Properties of Minerals 1.Crystal Form- How the different components solidified 2.Luster- the quality of light reflected from the surface 3.Color- impurities can make this variable 4.Streak- color of mineral in powdered form Trigonal Hexagonal Cubic
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Properties of Minerals Cont. 5. Hardness- classifying according to Mohs scale ( 1 being the softest and 10 being the hardest) 6. Cleavage/Fracture - based on the angle in which the mineral is broken off due to weak bonding planes 7.Specific gravity- the “heft” of the mineral, or how dense the mineral is 8.Other properties- smell, refraction, magnetism, feel, taste, reaction to HCL
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Mineral Groups Silicates- Composed mostly of silicon and oxygen and also with one or more metallic element (silicate tetrahedron) Examples: Quartz, Feldspar, Micas, Talc Carbonates - contains CO 3 a salt of carbonic acid. Examples: Calcite, Graphite Halides- contain chloride and flouride ions Examples: Halite and Flourite Oxides and sulfides -are minerals that have metals combined with oxygen or sulfur. Examples: Hematite, Magnitite, Pyrite, Galena, Sulfur
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Mohs Hardness Scale 4.5=
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Rocks A “rock” can be described as a naturally occurring aggregate - a combination of minerals We find three different types of rocks, they include Igneous Sedimentary Metamorphic.
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Rock Cycle
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Rocks Igneous- rocks that solidified from magma or lava Metamorphic- rocks that have undergone extreme heat and pressure Sedimentary- the collection or compaction of minerals and/or organic particles
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Igneous Extrusive- Formed from lava flows and eruptions from volcanoes –Produces our fine grained and glassy textures –Underwent a fast rate of cooling –(Basalt, pumice, obsidian)
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Igneous Intrusive- Formed from magma flows underground –Produces our coarse grained texture –Underwent a slow rate of cooling –(Granite, Gabbro, Diorite)
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Sedimentary Clastic- composed of fragments, or clasts, of pre-existing rock Classified by the size of particles –Conglomerate –Sandstone –Mudstone
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Sedimentary Organic- fossils that have been cemented together –Coal –Coquina Chemically- have mineral crystals made from elements that are dissolved in water. CaCO3 limestone Coquina
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Metamorphic Former Sedimentary or Igneous rocks that have undergone extreme heat and pressure
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Metamorphic
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Foliated Non-Foliated Foliated rock is a product of differential stress that deforms the rock in one plane Non- Foliated: Rocks that have undergone even more heat and don’t have any structural pattern
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