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Aim: How are minerals and rocks related to one another?. Do Now: Let’s look Mr. Rankin’s Famous Rock Video… This will give us a better idea of the environments of the three rock classifications. Rock :. A naturally formed mass that is usually composed of two or more minerals.
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Aim: How are minerals and rocks related to one another? Do Now: Let’s look Mr. Rankin’s Famous Rock Video… This will give us a better idea of the environments of the three rock classifications.
Rock: A naturally formed mass that is usually composed of two or more minerals. Monominerallic: Rock composed of one mineral Example: Rock Salt Halite
Polyminerallic: Rock composed of more than one mineral Example: Granite Potassium Feldspar, Quartz, Plagioclase Feldspar, Biotite, and Amphibole
Between a rock and a hard place… Rock Classification: Igneous:the cooling and solidifying of molten lava or magma. Sedimentary:the compaction and cementation of unconsolidated sediment and organic remains, and; the evaporation of a supersaturated solution
Metamorphic:the recrystallization of minerals due to intense heat and pressure. The addition of heated groundwater can also ‘change’ the existing minerals.
Summary On a separate sheet of paper answer the following: Name the three rock types. Using the ESRT, name two rocks that are monominerallic. Briefly describe the environment of formation for one of the rock types.
Aim: How can we describe igneous rocks? Do Now: Briefly describe the difference between molten rock magma and molten rock lava.
Lava Exterior, Outside Magma Interior
Igneous Rocks Igneous: A nonsedimentary rock formed by the cooling and solidifying of liquid rock (magma or lava).
Igneous Rocks Vocabulary Magma: Molten rock beneath the Earth’s surface. Lava: Magma that reaches the Earth’s surface. Crystallization: Minerals formed from the cooling of molten rock.
Texture: The “feel” of a rock due to the size, shape, and arrangement of mineral crystals, or sediments in a rock. Extrusive: Igneous rock that forms at the Earth’s surface (volcanic activity)
Intrusive: Igneous rock that forms at below the Earth’s surface (large magma body)
Using the diagram on pg. 6 of the ESRT, let’s practice reading the “Scheme of Igneous Rocks” using a worksheet.
Aim: How can the environment of formation determine the crystal size of igneous rocks? Do Now: Determine if the following rocks are mafic, felsic, or intermediate in composition: Andesite: Pumice: Basalt Intermediate Felsic Mafic
Review: What are the two environments igneous rocks can form in? Extrusive Intrusive Whether igneous rocks are extrusive or intrusive, they have intergrown crystals.
Intergrown Minerals (Crystals) Minerals fit together like a jigsaw puzzle
Extrusive: cooling and solidifying of molten rock lava. Fast cooling rates = fine (small) crystals less than 1 mm Rapid cooling = non crystalline Vesicular = gas pockets that formed when the rock solidified.
Glassy Texture Obsidian
Fine Texture Rhyolite
Vesicular Texture Scoria
Intrusive: cooling and solidifying of molten rock magma. Slow cooling rates = coarse (big) crystals, 1mm to 10 mm Very slow cooling = very coarse (very big) crystals, greater than 10mm
Coarse Texture Granite
Very Coarse Texture Pegmatite
Name a very light-colored, glassy, extrusive rock with bubbles.
Summary On a piece of paper, please answer the following question: Name the igneous rock that has a dark color, and; a glassy and vesicular texture.
Aim: How can we determine the percentages of igneous rocks? Do Now: Name the igneous rock that has a high concentration of Si and Al, coarse, low in density, and non vesicular. Granite
First Step: Locate the igneous rock you must identify by placing a dot in the center of the box. Find the intrusive igneous rock: Granite
Second Step: With a straight edge, draw a line from the dot to the mineral composition graph.
Third Step: Use a sheet of scrap paper and line it up parallel to the line you recently drew.
Fourth Step: Mark the boundaries of the minerals on the sheet of paper. Remember to label the mineral on the scrap paper.
Potassium Feldspar Plagioclase Feldspar Biotite Quartz Amphibole
Fifth Step: Slide the scrap paper the percentages column on the left side to determine the percentages of each mineral.
Potassium Feldspar Plagioclase Feldspar Biotite Quartz Amphibole
Sixth Step: To determine the percentages begin with the first mineral by 0%. Each interval is worth 5% For Granite: Amphibole = 7%
Seventh Step: To determine the percentages of the remaining minerals, you must bring the lowest boundary of that mineral to 0% to determine the remaining percentages. Repeat for each mineral present.
Potassium Feldspar Plagioclase Feldspar Biotite Quartz Amphibole
Determine the remaining percentages: Amphibole: Biotite: Plagioclase Feldspar: Quartz: Potassium Feldspar: 7% 13% 20% 40% 20% 100%
Summary 1. Determine the composition for the following igneous rocks: Dunite: Diorite: Which igneous rock is monominerallic? Olivine Plagioclase Feldspar, Biotite, and Amphibole Dunite