These are final exam questions. A group of 5 worked on them and most of them are completed. EVERY QUESTION HE ASKED ON THE EXAM WAS ON THIS LIST.

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University of Alberta
Earth and Atmospheric Sciences
Jeremy Richards

EAS 368 Ore Deposits Geology Example Final Lecture Exam Questions The exam usually offers a choice of 7 shortanswer questions from which you should pick 5 to answer Each question is worth 10 of the exam markWhat are the main ore minerals and economic metals mined from orthomagmatic a oxide and b sulfide deposits LucasOxide DepositsImportant ore minerals in orthomagmatic oxide deposits are chromite magnetite and ilmenite Have stratiform siderophile elements and compatible lithophile elements CrPGETiFe which are found within the above ore minerals PGEPlatinum Group ElementsStratiform deposits of chromite FeCrO occur in 24LMIs or anorthositic intrusive complexesChromitite chromite bearing rock can also occur in podiform deposits typically ophiolites of back arc basin originPGEs occur in stratiform chromite layers as arsenides sulfides antimonides with some Pt and AuPrimary ilmenite and magnetite deposits may have Ti Fe and V which occur in layered gabbroic intrusionsSulfide DepositsOre minerals are Nisulfides pentlandite with pyrrhotite chalcopyrite and magnetiteFe S O Ni are the main constituentsDeposits with gabbroic rocks will have high CuNi eg SudburyBriefly describe two suggested mechanisms for the formation of chromitite layers in layered mafic intrusionsCoreyLook at the chart under Orthmagmatic deposits page 4 last slide drawing those two diagrams would easily get 100 for this question From what I understand The two primary mechanisms are Assimilation of country rock by the magma which causes an increase in silica this in turn prevents olivine from crystallizing leaving chromite to be the only crystallizing phase The second mechanism is mixing of new magma in the magma chamber This works similar to the first mechanism by potentially increasing the the SiO content you again 2prevent minerals other than chromite from crystallizing If anyone Ryan understands this better they should edit this Diamonds are currently being recovered off the Namibian coastline From where were these diamonds derived and how were they deposited Why has this process resulted in deposits of particularly high diamond qualityRyan Theses diamonds were derived from kimberlites inland They were deposited byfluvial processes in fluvial terraces and submarine deltas This has resulted in high quality diamonds due to the transport process breaking down and destroying shitty diamonds and therefore selectively concentrating high quality diamondsWhat is the diamond pipeline Briefly explain how it works to control the price of rough diamonds1st mining companies conduct exploration on which economic projects proceed to the mining stage2nd rough diamonds extracted at the mines are bought by the central selling organizationCSO3rd is where single channel or supplier of choice marketing where stones are available for sale to a select group of clients 160 from the main cutting centers worldwide who submit requests for the type and quantity they want given proper market conditions the CSO will prepare packages of stones for the clients which are offered to them at 10 annual sights in london5th once jewellers acquire the packages of diamonds cutting and polishing is carried out in one of the four main centers worldwide antwerp Mumbaiparticularly skilled at polishing lower quality gem stonesNew York and Tel Aviv Mark Briefly describe the mechanism by which gemquality rough diamond prices are maintained at levels well above the utilitarian value of this mineral primarily the price for gem quality diamonds is controlled by market controls in which preferable sell rates are typically maintained by the major producers the major producers control the supply variable of the diamond market to produce favourable conditions for themselves The controlling stipulations of what makes a gemquality diamond and how they are brought to market is as follows first the value of diamonds depends on its weight and also its quality
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