Ge 262

lithosphere
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Vms hasZN.pb.Cu.Ag.Au metals are usual spatially zoned comes from subamarine hot springsCharacteristics of a mineral- Solid & stable at room temperature - Natural - Homogenous - Definite but not fixed chemical composition - Ordered atomic arrangementSILICATESQuartz, Feldspar, Mica, Wollastonite, Amphiboleschemical properties of wollastanite- Very strong fibrous chains (used in concrete, brake shoes, strengthening plastic, dental, and substitute for asbestos) - Chemical resistant - Thermally stable - Does not dissolve in acid - High length to aspect ratio - Hard - Increases tensile strength of plasticimportant sulfidepyrite,sphalerite,chalcopyrite,galena,molybdenite Why is Semiconduction a good property for sulfides? -Semiconducting properties can be exploited using geophysical measurements of outcrop electrical resistivitycomplete substitutionIf the sizes of the ions are nearly the same, the solid solution can occur over the complete range of possible compositions and the solid solution series is said to be complete.partialIf the sizes are only similar (somewhat different), the substitution may only occur over a limited range of compositions and the solid solution series is said to be partial or limited.end membersmineral composition limitscoupled solutionCoupled substitution occurs if an ion of different charge is substituted. This results in having to make another substitution in order to maintain charge balance.ommissionOmission solid solution occurs when an ion of higher charge substitutes for an ion of lower charge.,phyrhotitelaw of constancy of internal anglesThe shape of the crystal may be different, but the angles between the faces will be the same. Below, we see 2 shapes with different side lengths, but constant angles.Quartzo Hexagonal prism (m = 6) o Hexagonal dipyramid (m = 12)Group of mineralspyroxenes Formula W=Ca,Na X=Mg,Fe,Mn,Ni,Li Y=Al,Fe,Cr,Ti Z-Si,Alamphibole group56 124 cleavage Cleavage: a repetitious break on a parallel direction caused by weakness in the ATOMIC structurewollastaniteo Hard o Chemically resistant o Does not dissolve in acid o Has Fibers o Used as a filler - used in plastics (tables, cars). Increases the strength and is very cheap (in a plastic blend). Used in automobiles (especially in break pads - heat resistant and very hard) o Chemically inert and thermally stableTHE DIFFERENCE BETWEEN PYROXENE AND AMPHIBOLEdifference in the cleavage amphiboles will have hydrogen,they are formed with water o Water vs. No water o Single Chain vs. Double ChainCRYSTAL- Solid material in which atoms or molecules are arranged in an ordered pattern extEnding in 3-D.Has symmetric plane faces.wollastanite- Very strong fibrous chains (used in concrete, brake shoes, strengthening plastic, dental, and substitute for asbestos) - Chemical resistant - Thermally stable - Does not dissolve in acid - High length to aspect ratio - Hard - Increases tensile strength of plasticwhy is wollastanite valuable-Deposit is valuable if close to the surface and ore is easily disseminated -Wollastonite has a high length to aspect ratioAbsetos-Asbestiform" amphibole (mineral) - cleavage needles of amphibole -Asbestiform Serpentine (mineral) - rolls of sheetschrysotioleLayered silicate structure rolled up into to tubes (not near as-hazardous),iron free mineral -dissolves quickly in your lungsProperties of abestos- Fine, flexible, can be woven - Source of fibre - flameproof - Chemically inert - Water & heat resistant, - Can be mixed and used as a reinforcement for other materialsamosite/crocidoliteenter, clog and splinter the alveoli of the lungs creating scar tissueAbestos causesLung cancer, mesothelioma, asbestosis, and pleural disorders, cancer of esophagus, stomach or coloninterstital solid solutionOccurs where there are sites that are not normally occupied by ionsFactors affecting solid solutionso Atomic/ionic size o Temperature o Structural flexibility o Cation Chargepotassium feldsparperthile texture (with the "veins")Piezoelectricdeformation causes a polarity to developcrystallization1000m, at 25 degrees celsius Calcite (or aragonite) Gypsum Anhydritecarbonates and sulfatesform at low temperatures compared to silicates carbonates:triagonal planar shape sulfates:tetrahedral shapeconcretesilicon-oxygen bondssulfatesgypsum which is used for dry wall weak bond strengthoxides• No general planes of weakness • Chromite is formed in LAYERS in the rock (very valueable. Large horizotal extent) • Chromite is used for: Stainless steel, must be about 10% wt. chromiumheat tranfersconvection conduction radiationbushveld -South Africatemperature of 1200 degrees celsius very hot liquid at the time and the mantle was thin which allowed the settling of magma mafic magma rose through the chamber and settled out based on density. utlramafic primitive rocks platnium and chromite came through thin crust the earth tilted,eroded and faulted creating layered deposits to reach the surface.formation of chromite layerFractional crystallizatio Increasing the oxygen fugacity Changes in total pressureSudbury Depositiron,nickel,copper -meteor hit on a junction ,or a plane of weakness that changed the geological features of the earth -magma chamber with sulfides began to form -heavy blobs began to sink to the bottom of the chamber and the liquids(silicates remained above -immiscible materials sweep out metals (pulls it all together)sedex deposits-Form near VMS deposits similar concentration mechanism Sulfide deposits formed in a sedimentary basin by the submarine venting of hydrothermal fluids and whose principal ore minerals are sphalerite and galena SEDEX is the #1 source of zinc mine what USED TO BE the ocean floor, that has since been pushed up Water picks up evaporates (gypsum, salt - NaCl), and forms saline brines, which are very effective at stripping metals• Tectonic settingAssociated with sedimentary basins that are controlled by subsidence associated with Major rifts Failed intercontinental riftsporphry coppermetals are copper,molybdenum,silver and platinumhow prophry formsPorphyry deposits form above large magma chambers (volume > 100km3) at a depth that is deep enough to get hot but not so deep that rocks become plastic and don't crack. formed when column of rising magma is cooled Meteoric water is introduced to the hot, dry rock above the magma chamber and expands and causes cracks sulphide comes in and fills cracks These cracks form a complex network veinlets called a stockwork water and steam from magma chamber dissolves metals and force their way through the stockwork/veinlets loss of water causes crystalization enclosing earlier crystals ina a fine grained mass (porphyritic texture) ore minerals like chalcopyrite and bornite fill the veinsvms deposits and sed exdeposited on the sea floor at the same time as the host rock massive sulfide bedded exhalative lenses with underlying feeder zones formed in clusters or stacked lenses metal transported as chloride complexes In brines sulfide lenses are highly deformeddifferencessed ex deposits are formed in fault bounded sedimentary basins on continental crust rather than volcanic piles on oceanic crust host rocks for sedex deposits are oxygen deprived products such as shales and volcanics are rare hydro thermal system is from depth of burial rather than a felsic intrusion rather a mafic intrusion vms:CU au Zn and sed ex :PB AND Ag Zn deep basins needed and there 125 sed ex depsits in the world Source of significant Ob and Znuraniumhard silver grey metal but never occurs in metallic form in nature. yellow green in color primary(uranium is introduces with magma and secondary where uranium is dissolved by groundwater and then redopsiteduraniumcool shallow saline oxidizing underground water from basaltic 44.hazards associated with radon gas is easily diluted.Health dangers are minimized by using remote mining :hydraulic mining and slurry pumping mininiminzing dust in situ leaching is used where u is in sandstone is confined by mudstone or shale...ore is crushed and slurry to the mill. It relies on the ph changes and the solution may be slightly acid.A weak acid of hydrogen pyroxide solution is added so that uranium is dissolves .After purification ammonium sulfate is added and allow it to precipitateurnot rare occurs in most rocksuranium-sandstone - Impermeable shale or mudstone is interbedded in the sedimentary sequence and often occur immediately above or below the mineralized horizon -uranium is mobile in oxidizing conditions and precipitates in reducing conditions, therefore reducing is essential -primary mineralization consists of pitchblende, coffinite and weathering results in secondary mineralizationuraniumUnconformity Related Deposits -geological changes occurring close to major unconformities -unconformity is a buried erosion surface separating two rock masses of 2 ages therefore sedimentation is not continuous (unconformity) -metasedimentary rocks host mineralization are faulted and brecciated and leads to mineralization of uranium into uraninite/pitchblende