储量定义美国资源局精.docx
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储量定义美国资源局精.docx
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储量定义美国资源局精
192
APPENDIXA
AbbreviationsandUnitsofMeasure
1carat(metric(diamond=200milligrams
1flask(fl=76pounds,avoirdupois
1karat(gold=onetwenty-fourthpart
1kilogram(kg=2.2046pounds,avoirdupois
1longton(lt=2,240pounds,avoirdupois
1longtonunit(ltu=1%of1longtonor22.4poundsavoirdupois
longcalcinedton(lct=excludeswaterofhydration
longdryton(ldt=excludesexcessfreemoisture
Mcf=1,000cubicfeet
1metricton(t=2,204.6pounds,avoirdupoisor1,000kilograms
1metricton(t=1.1023shortton
1metrictonunit(mtu=1%of1metrictonor10kilograms
metricdryton(mdt=excludesexcessfreemoisture
1pound(lb=453.6grams
1shortton(st=2,000pounds,avoirdupois
1shorttonunit(stu=1%of1shorttonor20pounds,avoirdupois
shortdryton(sdt=excludesexcessfreemoisture
1troyounce(troz=1.09714avoirdupoisouncesor31.103grams
1troypound=1
2troyounces
APPENDIXB
DefinitionsofSelectedTermsUsedinThisReport
TermsUsedforMaterialsintheNationalDefenseStockpileandHeliumStockpile
UncommittedinventoryreferstothequantityofmineralmaterialsheldintheNationalDefenseStockpile.Nonstockpile-gradematerialsmaybeincludedinthetable;wheresignificant,thequantitiesofthesestockpiledmaterialswillbespecifiedinthetextaccompanyingthetable.
Authorizedfordisposalreferstoquantitiesthatareinexcessofthestockpilegoalforamaterial,andforwhichCongresshasauthorizeddisposaloverthelongtermatratesdesignedtomaximizerevenuebutavoidunduedisruptionoftheusualmarketsandfinanciallosstotheUnitedStates.
DisposalplanFY2011indicatesthetotalamountofamaterialintheNationalDefenseStockpilethattheU.S.DepartmentofDefenseispermittedtosellundertheAnnualMaterialsPlanapprovedbyCongressforthefiscalyear.FY2011(fiscalyear2011istheperiodOctober1,2010,throughSeptember30,2011.Formineralcommoditiesthathaveadisposalplangreaterthantheinventory,actualquantitywillbelimitedtoremainingdisposalauthorityorinventory.Notethat,unliketheNationalDefenseStockpile,heliumstockpilesalesbytheBureauofLandManagementundertheHeliumPrivatizationActof1996arepermittedtoexceeddisposalplans.
DisposalsFY2011referstomaterialsoldortradedfromthestockpileinFY2011.
DepletionAllowance
Thedepletionallowanceisabusinesstaxdeductionanalogoustodepreciation,butwhichappliestoanorereserveratherthanequipmentorproductionfacilities.Federaltaxlawallowsthisdeductionfromtaxablecorporateincome,recognizingthatanoredepositisadepletableassetthatmusteventuallybereplaced.
193APPENDIXC—ReservesandResources
Reservesdataaredynamic.Theymaybereducedasoreisminedand/ortheextractionfeasibilitydiminishes,ormorecommonly,theymaycontinuetoincreaseasadditionaldeposits(knownorrecentlydiscoveredaredeveloped,orcurrentlyexploiteddepositsaremorethoroughlyexploredand/ornewtechnologyoreconomicvariablesimprovetheireconomicfeasibility.Reservesmaybeconsideredaworkinginventoryofminingcompanies’supplyofaneconomicallyextractablemineralcommodity.Assuch,magnitudeofthatinventoryisnecessarilylimitedbymanyconsiderations,includingcostofdrilling,taxes,priceofthemineralcommoditybeingmined,andthedemandforit.Reserveswillbedevelopedtothepointofbusinessneedsandgeologiclimitationsofeconomicoregradeandtonnage.Forexample,in1970,identifiedandundiscoveredworldcopperresourceswereestimatedtocontain1.6billionmetrictonsofcopper,withreservesofabout280millionmetrictonsofcopper.Sincethen,about400millionmetrictonsofcopperhavebeenproducedworldwide,butworldcopperreservesin2011wereestimatedtobe690millionmetrictonsofcopper,morethandoublethosein1970,despitethedepletionbyminingofmorethantheoriginalestimatedreserves.Futuresuppliesofmineralswillcomefromreservesandotheridentifiedresources,currentlyundiscoveredresourcesindepositsthatwillbediscoveredinthefuture,andmaterialthatwillberecycledfromcurrentin-use-stocksofmineralorfrommineralsinwastedisposalsites.Undiscovereddepositsofmineralsconstituteanimportantconsiderationinassessingfuturesupplies.USGSreportsprovideestimatesofundiscoveredmineralresourcesusingathree-partassessmentmethodology(SingerandMenzie,2010.Mineral-resourceassessmentshavebeencarriedoutforsmallparcelsoflandbeingevaluatedforlandreclassification,fortheNation,andfortheworld.
ReferenceCited
Singer,D.A.,andMenzie,W.D.,2010,Quantitativemineralresourceassessments—Anintegratedapproach:
Oxford,UnitedKingdom,OxfordUniversityPress,219p.
PartA—Resource/ReserveClassificationforMinerals
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