Geology midterm review PDF

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Download Geology midterm review PDF

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Minerals: ●

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Physical properties ● Luster ● Appearance in reflected light ● Terms (know what each of these look like): metallic, vitreous, pearly, resinous, waxy, greasy, silky, dull and earthy ● Cleavage ● Tendency of a mineral to break along specific planes of weakness (flat edges that flash at you all at once when you look at them in light) ● The number of sets of parallel planes and the angles between those planes ● One direction: muscovite, biotite, gypsum etc ● 2 directions at 90 degrees: plagioclase, orthoclase etc ● 3 directions at 90 degrees (cubic): halite, galena, pyrite etc. ● 3 directions at 75 degrees: CALCITE!!!! ● Four directions: fluorite etc ● Fracture ● How a mineral tends to break ● Conchoidal-circular, quartz ● Uneven/ irregular (if it has cleavage it is this and the majority of minerals is this) ● Fibrous ● Diaphaneity ● The ability to transmit light ● Transparent- can read letters through the mineral ● Translucent- can see light coming through but can’t make out letters ● Opaque-no light comes through ● Tenacity ● Resistance to breaking and how it will react when stress is applied ● Elastic- bounces back to its original shape ● Flexible- bends but does not return to original shape ● Malleable- can be hammered to thin sheets ● Brittle- shatters/ breaks ● Sectile- can be shaven into thin sheets ● Hardness ● Moh’s Hardness Scale ● 1-talc, 2-corundum, 3-calcite, 4-fluorite, 5-apatite, 6-orthoclase, 7-quartz, 8-topaz, 9-corundum, 10-diamond ● These are the only minerals that you have to know hardness for! ● Glass is 5.5-6, fingernail is 2.5 and steel in 6.5 ● Other ● Taste- halite tastes salty ● Smell- sulfur smells like rotten eggs when scratched with a nail, so does sphalerite ● Streak- some minerals have a distinctive color when scratched on porcelain (hematite is dark red) ● Magnetism- MAGNETITE IS MAGNETIC ● Reaction with ACID- Calcite bubbles readily with acid but dolomite only reacts when powdered (KNOW THIS!!) Composition groups ● Know the main composition groups ● Silicates, sulfides and sulfates and what minerals go in these groups Uses ● Know at least one modern day use for each of the minerals (the flash cards will help you with this)

Igneous Rocks: MUST BE ABLE TO IDENTIFY ALL OF THESE ROCKS (use your flashcards to help with this) ●

Texture ● Phaneritic - can see large grains

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● Aphanitic -can not see any grains in hand sample ● Porphyritic - large grains in a fine matrix ( has both of the above sizes) ● Glassy -no grains at all (pumice and obsidian) ● Fragmental - blown out from the volcano (Tuff) ● Vesicular -has holes where gas escaped (Scoria, vesicular basalt) Minerals composition (know some common minerals in each rock) ● Felsic - Llanite, Rhyolite, granite, Tuff, pumice, syenite ● Intermediate -obsidian, diorite, andesite ● Mafic -Scoria, gabbro,basalt, vesicular basalt ● Ultramafic - peridotite Origin ● Intrusive - formed inside the earth, cooled slowly, large crystals ● Extrusive - formed on the surface, cooled quickly, no visible crystals

Sediments: ●

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Sediment Size ● Gravel - large grains ● Sand - coarse, but smaller than gravel, looks like beach sand ● Silt - finer than sand but still a little gritty in the hand and rough on the teeth ● Clay - smallest, feels smooth in hands and on teeth Roundness ● Angular - very sharp and pointy ● Sub-angular - starting to round off the sharp edges ● Sub-rounded - smooth edges but still irregular shape ● Rounded - almost circular, very smooth Sorting ● Well sorted - all grains are the same size ● Moderately sorted - kind of in the middle, grains are closer to the same size, but are still different ● Poorly sorted - grains are all different sizes Environments ● If sediment is larger in size, angular and poorly sorted it is close to the source ● If the sediment is smaller, rounded and well sorted then it is farther from the source Weathering ● Mechanical = Physical=no change in the composition ● Abrasion, crystal (freeze-thaw) wedging, etc ● Chemical =changes in the rock composition ● Know dissolution

Sedimentary Rocks: KNOW HOW TO IDENTIFY THESE!!!! Use your flashcards ●

Types ●

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Detrital ● Classified by grain size ● Sandstone, siltstone, shale, conglomerate and breccia Chemical Precipitant ● Classified by the mineral composition ● All other sedimentary rocks

Texture ● Clastic ● Composed of pieces of other rocks, minerals or plant fragments ● EX: Quartz sandstone, arkose, siltstone, breccia, conglomerate, coal, coquina, shale, fossiliferous limestone, chalk, oolitic limestone, ● Crystalline ● Made entirely of one mineral, looks kind of like a crystal ● EX: Micrite, rock salt, travertine, gypsum, dolomite, chert(flint and jasper) Depositional environments ● Conglomerate/breccia =alluvial, fluvial, glaciers

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● Sandstones =Rivers, beaches, Aeolian (deserts) ● Limestones =shallow marine ● Rocksalt = deserts, etc Fun facts, need to know!!!! ● Chert has conchoidal fracture ● Rocks that contain calcite ● F. Limestone, oolitic limestone, micrite, travertine, coquina, chalk ● Chalk and Rock Gypsum are very similar in appearance, but gypsum looks more crystalline ● Halite dissolves in water

Metamorphic Rocks: KNOW HOW TO IDENTIFY THESE!!! Use your flashcards ●

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Types of metamorphic fabrics ● Recrystallization ● Grain size increases ● Recombination ● Changes minerals to new minerals ● Rotation ● Grains re-align to minimize stress from directed pressure Textures ● Foliated = planar or layered appearance due to high grade ● Slate, phyllite, chlorite schist, mica schist, gneiss ● Non-foliated = random arrangement of minerals ● Marble, quartzite, meta-conglomerate, anthracite Grade ● Low = very early in metamorphic history ● Marble, slate ● Intermediate =a little bit more change ● Schists, phyllite, metaconglomerate, quartzite ● High = completely different rock, high level of change ● Gneiss Parent Rocks ● Shale = slate, phyllite, schist, gneiss ● Limestone = marble ● Sandstone =quartzite...