GLY 2160 Class notes - Geology of National Park Class Notes...

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Geology of National Park Class Notes Minerals, Rock Cycle, Igneous, Sedimentary, Metamorphic Rocks Minerals: Building Blocks of rocks. Mineral vs. Rock: Rocks are aggregates of minerals Definition:- Naturally occurring, inorganic solids that possess a definite chemical structure . (chemical composition). 4,000 minerals exist. 1. Elements: building blocks of minerals (112 known, see Periodic Table) Some minerals made up of only one element e.g. gold, sulfur. Most elements not stable alone therefore most minerals are a combination of 2 or more elements that form a stable compound . Physical Properties of Minerals : 1. Crystal Form -expression of orderly arrangement of atoms. If space available. e. g. quartz 2. Luster- light reflected on surface. Metallic vs. non metallic 3. Color -unreliable. e.g. quartz- impurities change color 4. Streak -colored of mineral in powdered form. More reliable than color . 5. Hardness : Mohs Scale (Table 1.1 p. 17) <2.5 scratched by a fingernail 2.5 to 3 scratched by a penny 3 to 5.5 scratched by a pocket knife 1.5 to 7 scratched by quartz >7 cannot be scratched by quartz 1. TALC 2. GYPSUM 3. CALCITE 4. FLOURITE 5. APATITE 6. FELDSPAR (K) 7. QUARTZ 8. TOPAZ 9. CORUNDUM 10. DIAMOND ****The hardest minerals make good gemstones and abrasives. 6. Cleavage -tendency of mineral to break along planes of weak bonding. Use micas as example. Do not confuse with crystal form. 7. Fracture- Minerals with out cleavage exhibit fracture. Conchoidal smooth like glass vs. fibrous. Most minerals have irregular fracture. 8. Specific Gravity- wt. of mineral compared to wt. of equal vol. of H2O 9. Other: Taste, Smell, feel. Double refraction, reaction with HCl, magnetism… ***There are nearly 4000 minerals however only a few dozen are abundant and these few make up most of the rocks of the earth’s crust. Only 8 elements make up the bulk of these minerals. O, Si, Al, Fe, Ca, Na, K, Mg. Mineral Groups: Silicates are most common rock forming. The Rock Cycle: Proposed by James Hutton in the late 1700’s Three Types of Rocks and their relationships:- Igneous, Sedimentary, Metamorphic. Molten magma undergoes crystallization either beneath or at the surface to form igneous rocks. Exposed igneous rocks undergo weathering and rocks are decomposed into sediment. Sediment is deposited by erosional agents (gravity, running water, glaciers, wind, waves). Sediment deposited in horizontal beds and undergoes lithification by being compacted and cemented. This results in sedimentary rocks. If sedimentary rocks are buried deep within the earth the heat and pressure will change sedimentary rocks into metamorphic rocks. When metamorphic rock is subjected to greater heat and pressure it melts to create magma completing the rock cycle. ***The
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This note was uploaded on 04/13/2010 for the course GLY 2160 taught by Professor Haberfeld during the Spring '10 term at Tallahassee Community College.

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GLY 2160 Class notes - Geology of National Park Class Notes...

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