Planet Earth Exam 2 Study Guide Minerals Building blocks of rocks and earth Conditions o Naturally occurring o Solid o Orderly arrangement of atoms in crystal lattice o Inorganically formed No carbon o Definite chemical composition o Homogeneous External formed controlled by internal elements Crystals single continuous solid bounded by flat surfaces that grow naturally when mineral formed Crystallography study of crystals o Symmetry Reflection across a plane Axis of Rotation Glass is not a mineral amorphous lacks crystalline structure Ice is mineral Growth of mineral o Freezing or cooling of a liquid o Precipitation o Hydrothermal deposits Euhedral well formed face cube hexahedral subhedral crystals touch and lose shape anhedral without any crystal faces ID of Minerals o Color o Streak o Luster o Hardness diamond 10 tale 1 o Cleavage sheet silicate o Fracture o Crystal Habit Shape o Density Magnetism Effervescence Fluorescence Luminescence taste texture Polymorphs same composition different crystal structure graphite diamond is carbon Igneous Rocks Igneous Activity Distribution o Tracks tectonic plate boundaries o Magmatic activity hot spots at all boundaries Igneous Volcanic Rocks o Molten rock that becomes frozen Magma Formation o Up from the mantle o 1 Lower pressure in mantle causes rock in mantle to melt o 2 Effect of volatiles decrease melting point o 3 Heat transfer melting of crust and lithospheric mantle Extrusive volcanic above surface rapid cooling small crystals Intrusive plutonice below surface slow cooling big crystals don t surface dikes sills and plutons Magmatic Differentiation different kind of magma depends on o Source rock composition o Partial melting o Assimilation o Magma Mixing o Fractional Crystallization Bowens reaction series series of reactions that take place in silicate magmas as they cool o Tells us the whole process of igneous rocks being formed o Olivine Pyroxene Amphibole Biotite Quartz Magma Composition o Ultramafic 45 silica o Mafic Mg and Fe 52 silica darker low viscosity runny o Intermediate 66 silica o Felsic Feldspar and silica 76 silica lighter high viscosity Crystallization depends on amount of time that magma cools controls ending grain size o Slower the cool the coarser bigger the grain Glass is igneous rock formed very quickly Volcanic Eruptions Volcanism process of magma breaching land surface and running on the crust o Magma at surface is lava Volcano Components o Summit Flank vent flanks chimney magma chamber Caldera large circular depression with steep walls and flat floor formed after eruption Volcano Status active volcano dormant volcano extinct volcano Diatreme exposed volcanic pipe Composition temperature and of dissolved gases in magma effects volcanic activity Types of Volcanic Eruptions o Effusive basalt lava flows from low viscosity lavas and spreads hundreds of miles o Explosive high viscosity high in trapped gases blast away lava and debris o Phreatomagmatic water enters magma chamber and steams at high pressure explodes Ash fall tephra lithified ash tuff Deposits from pyroclastic flow is ignimbrites Types of Volcanoes o Shield Volcanoes oceanic hot spots and divergent boundaries mafic o Cinder Cones central vent filled with rock frags o Composite or Stratovolcano central vent filled from previous eruption felsic Volcanic Hazards Volcanic Gases o Explosion blowdown landslides earthquakes tsunamis lava flow mudflow pyroclastic flow super heated clous of gas ash and rock o Steam H20 Carbon Dioxide CO2 and Hydrogen Sulfide H2S Sedimentary Rocks Formed at or near the surface by o Cementing fragments or loose grains derived from existing rocks o Precipitation of minerals o Growth of skeletal material in organism Life Cycle of Sedimentary Rocks o Break apart existing rocks and minerals to form sediment weathering o Move sediment particles erosion and transport o Redeposit or precipitate the sediment sedimentation deposition o Consolidate cement and lithify into rock lithification Occur in upper crust as veneer covering igneous and metamorphic rocks 80 of earths surface but less than 1 of its total volume Accumulates in layers to give record of events and environments Sediments o Loose rock frags mineral grains shells mineral crystals out of water Weathering break up and decomp of rock as surface to more stable forms under weather conditions o Mechanical or Physical smaller pieces without changing composition Jointing exfoliation of granite or basalt Thermal contraction joints form as massive lava sills cool and shrink Thermal expansion heat rock expand cool contract and break Wedging freeze thaw cycles pry open cracks o Chemical change into more stable compounds which favor chem Weathering mainly caused from water quest for stability Dissolution minerals dissolve in water acid increases rate Oxidation losing electrons from oxygen Erosion incorp and downhill transport of sediments by gravity water wind and ice Soil sediment that can support plant life Soil Formation o Rock type or substrate different rocks make different soil chemistry o Climate high rainfall yields more minerals o Topography flat thicker steep thinner o Time o Vegetation plants add remove nutrients and organic matter Lithification transformation of loose sediment into rock through compaction and cementation o Compaction pressure squeezes out air and water pressing clasts tighter together o Cementation fill space with cement precipitated from groundwater Transportation mainly water o High energy rivers glaciers landslides move rocks o Low energy removes smaller grains rocks behind Rock Classes o Clastic or Detrital cemented loose sediments from weathering of rocks Categorized based on grain size Sizes Boulder Cobble Pebble Sand Slit Clay Breccia angular clasts poorly sorted high energy Conglomerate rounded clasts poorly sorted high low energy Sandstone moderate currents river wind beach Siltstone low energy environment offshore lagoon lake Clay finer than silt lowest energy Sorting Different velocities in wind and water currents separate grain sizes and Range of grain sizes within a sediment densities Sphercity and Roundness o Biochemical composed of shells and shell debris reacts with acid Fossil Limestone reef environment sunlight Coquina poorly cemented shells beach Carbonate Chalk Siliceous bedded biochemical chert indicates a strictly marine origin o Organic Carbon rich rocks derives from decayed plant material Coal o Chemical precipitate from water