NUMBER 169 DECEMBER 2015-Version 2 Gold Homogeneity in ... Number... · The December 2015 issue of EXPLORE features a technical article about gold homogeneity in certified reference

NUMBER 169 DECEMBER 2015-Version 2

Second Version issued December 3, 2015Newsletter for the

Association of Applied Geochemists

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Gold Homogeneity in Certified Reference Materials; A Comparison of Five ManufacturersN. W. Brand, Geochemical Services Pty Ltd., Suite 10, 5 Colin Street, West Perth, 6005, Australia, [email protected]

INTRODUCTION CertifiedReferenceMaterials(CRMs)insertedintoanalyticalbatchesarearequirementbytheinternationalcodesgoverningthemineralindustry(JORC2012;NI43-101;SAMREC)andreportingtothestandardslaidoutinthesecodesisamandatorycomplianceforpubliclylistedcompaniesontheAustralian,NewZealandandCanadianStockExchanges.ACRMisasamplewheretheconcentra-tionsofoneormoreanalyteshavebeenquantifiedbyvalidmethodologiesandcertifiedwithvaliddocumentation.Thesecertifiedvaluesaretheconsensusinter-laboratorymeanforananalytewheretypicallyeachlaboratoryanaly-sesmultiplesubsamplesoftheCRM. Forgold(Au)CRMs,oneofthekeypropertiesisthehomogeneityoftheCRMsample(i.e.testingfornuggeteffects).QuantifyingthishomogeneitybytheRelativeStandardDeviation(RSD)iscriticalforassessmentoflaboratoryresultsandthefollowupofqualitycontrol(QC)failures. Thereisvastliteraturediscussingthenuggeteffectingoldmineralisingsystemsandprotocolsinreducingthesamplingerror(e.g.,Stanley&Smee2007),butverylittleinformationhasbeenpublishedonthehomogeneityofgoldCRMs.BytheirverynatureCRMsareassumedtobehomogeneousandanyvariationisattributedtolabora-toryerror(i.e.thevarianceattributedtothesamplingerrorislessthantheanalyticalerror);sohowhomogenousarecommercialgoldCRMs? ThehomogeneityofagoldCRMsamplereflectsthecapabilityandcompetencyofamanufacturertoeliminateanynuggeteffectsandprovideahomogeneousproductthat,whenanalysed,willprovidearepeatableresultwithinthestatisticallimitsprovidedontheCRMcertificate.Al-thoughallmanufacturesrefertothehomogeneityoftheirCRMs,onlyonemanufacturer(OREAS),measuresthehomogeneityoftheCRMsandprovidesthisinformationasroutinewiththeirgoldCRMCertificateofAnalysis.Rock-labsundertakeahomogeneityandsegregationtest,butdonotprovidetheactualhomogeneityresults. ThisindependentstudyevaluatesthehomogeneityofgoldCRMsfromcommercialCRMmanufacturersatfourchosengoldgrades(0.5ppmAu,1ppmAu,3ppmAuand9ppmAu).Thesegradesaretypicalinminingandexplo-rationscenariosandreliableQCdataatthesegradesiscritical.Thisstudyprovidesabenchmarkforfurtherevalu-

ationsofpotentially“nuggetty”CRMproductsincluding,butnotrestrictedto,platinumgroupelements(PGEs),rareearthelements(REE),andAu.

CRM MANUFACTURERS AND THEIR PREPARATION FourauriferousCRMSfromeachoffivemanufactur-erswereassessed(i.e.20CRMsintotal).TheCRMsweresourcedfromfivemanufacturers,aslistedbelowalphabeti-cally.AsummarydescriptionofthepreparationprocessisalsoprovidedandtakenfromtheirCRMcertificates:

•AfricanMineralStandards(AMIS):http://www.amis.co.za/.Thematerialwascrushed,dry-milledandair-classifiedto<54microns.Wetsieveparticlesizeanalysisofrandomsamplesconfirmedthematerialwas98.5%<54microns.Itwasthenblendedinabi-conicalmixer,systematicallydividedandthensealedinto1kgLabora-toryPacks.

•CDNResourceLaboratoriesLtd(CDN):http://www.cdnlabs.com/.Materialwasdried,crushed,pulverizedandthenpassedthrougha270meshscreen.The+270meshmaterialwasdiscarded.The-270mesh(53microns)ma-terialwasmixedfor5daysinadouble-coneblender.

•GeostatsPtyLtd(GST):http://www.geostats.com.au/.AllCRMsaredriedinanovenforaminimumof12hoursat110°C.Thedrymaterialisthenpulverisedtofinerthan75microns(nominalmeanof45microns)usinganairclassifier.Thematerialisthenhomogenisedandstoredinasealed,stablecontainerreadyforfinalpackaging.

•OreResearchandExplorationPtyLtd(ORE):http://www.ore.com.au/.Materialsarejawcrushedtominus3mm,driedtoconstantmassat105°C,barrenmaterialsaremilledto>98%minus75micronsandgoldbearingmaterialmilledto100%minus20-30microns,blendinginappropriateproportionstoachievethedesiredgrade,packaginginto60gand100gunitsinlaminatedfoilpouchesand1kgunitsinplasticjars.

•Rocklabs(RLB):http://rocklabs.com/.Pulverizedfeld-sparminerals,basaltrockandbarrenironpyriteswereblendedwithfinelydividedgoldcontainingmineralsthathavebeenscreenedtoensurethereisnonuggettygold.(NOTEnosizinginformationprovided).

SeealsoTable1forasummary.

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Notes from the Editor

TABLE OF CONTENTSGoldHomogeneityinCertifiedMaterials:AComparison

ofFiveManufacturers.......................................................... 1

NotesfromtheEditor............................................................... 3

President’sMessage.................................................................. 4

GeochemicalNuggets............................................................... 17

JoinUsforExploration17....................................................... 17

Minutesofthe2015AAGAnnualGeneralMeeting............ 18

RecentlyPublishedinElements.............................................. 19

EricL.HoffmanMemorialScholarship................................. 19

AAG’sStudentSupportProgramRessurectedin2015......... 20

TreatiseofGeochemistry.......................................................... 20

Student-IndustryMineralExploration

Workshop............................................................................... 21

AAGNewMembers................................................................. 21

CalendarofEvents.................................................................... 23

ADVERTISERSActivationLaboratoriesLtd..................................................... 24

AGATLaboratories.................................................................. 22

ALS ........................................................................................... 4

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OREResearchandExploration.............................................. 2

SciApps,Inc............................................................................... 7

NewsletterNo.169 DECEMBER2015

Editor:BethMcClenaghan([email protected])

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TheDecember2015issueofEXPLOREfeaturesatechnicalarticleaboutgoldhomogeneityincertifiedreferencematerialsbyNigelBrand.EXPLOREthanksallcontributorstothisfourthissueof2015:SteveAmor,AlArsenault,DennisArne,NigelBrand,BobGarrett,PimvanGeffen,MattLeybourne,PaulMorris,JamilSader,andDaveSmith.Inthislastissueof2015,EXPLOREgratefullyacknowledgesourthreecorporatesponsorsfortheyear,ALSMinerals,AGATLaboratories,andREFLEXGeo-chemistry,aswellasouradvertizersfortheircontinuingfinancialsupportofEXPLORE.PimvanGeffen,ourBusi-nessManager,isthankedformanagingthefinancialaspectsofpublishingEXPLOREincludingcorporatesponsorsandadvertizers.PimandIwishallAAGmembersandotherreadersofEXPLOREasuccessful2016.

Beth McClenaghanEditor


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2016-2017,ablyassistedbySteveCookfromTeckResourc-esLimitedasVicePresident.Thepasttwoyearshave,asweallknow,beenverydifficultwithamajorandsustainedslow-downinthemineralexplorationindustry.Despitethat,theAssociationcontinuesunabatedwithanumberofsignificantmilestones.SinceBobEppingerpennedhisfinalPresidentialmessage(December2013EXPLORE),theAssociationhasheldtwosuccessfulIAGSconferences(Rotorua,2013andTucson2015),implementedanumberofsocialmediaavenuesofmemberexpression(LinkedIn,Facebook),andsuccessfullytransitionedtoanewEditor-in-Chief(KurtKyser)forourjournalGEEA.Ihopethatyouareallworkingdiligentlytoproducelargequantitiesofhigh-qualitypaperstoinundateKurtwith,ashehasalotoftimeonhishands.AsIhavestatedbefore,butitbearsrepeating,GwendyHalldidanoutstandingjobasourEditor-in-ChiefpriortoKurttakingover.Thankfully,shecontinuestomanagethearduoustaskofmaintainingandgrowingtheAssociationinvestmentsandoverallfinancesastheAAGTreasurer.DanLayton-Matthewsisthe2015-2017AAGDistinguishedLecturerand,withfinancialsupportfromtheAssociationfortravel,isavailabletopresentatalkataninstitutionnearyou.PleasegetintouchwithDantoorganizealecturetour([email protected]). IwouldliketoexpressmythanksandgratitudetoallmembersofCouncilfortheireffortsoverthelasttwoyears,andtoallAAGmemberswhocontinuetosupport

theAssociation.IwouldparticularlyliketothankmyVice-President,RyanNobleforhishelp,aswellasGwendyHall(Treasurer),DaveSmith(Secretary),BethMcClenaghan(EXPLOREeditor),PimvanGeffen(EXPLOREBusinessManager),PatricedeCaritatandDennisArne(Elementscoordinators),KurtKyser(GEEAEditor),2014-2015Councillors(AlejandroArauz,DennisArne,StephenCook,MeltLintern,PaulMorris,PeterSimpsonandBobEp-pinger),andthe2015-2016Councillors(DaveCohen,RayLett,TomMolyneux,JuanCarlosOrdóñezCalderón,PeterRogers,andPeterWinterburn).AlsodeservingofgratitudeareGemmaBonham-CarterandBrunoLemierefortheireffortsmaintainingandmanagingtheAssociationWebsite.IalsothankalltheRegionalCouncillors,andAAGCom-mitteemembersforalloftheirwork. Finally,anotherchangeoverthelasttwoyearswasthepassingofthereinsofmanagingourAssociationfromBettyArsenaulttoherhusbandAlArsenault;bothhavebeenindispensible,andithasmadethingseasierthattheycoinci-dentallyhavethelastname. Sadly,wehavealsolostsomeofthegreatsinourfieldoverthelastcoupleofyearsincludingEionCameron,BillCoker,andEricHoffman;allofthemaregreatlymissed. Toclose,Iwishtheincomingpresidentandvice-pres-identanoutstandingandsuccessfultwoyears.IhopethattheindustryisontheupswingthatwilltranslatetoastellarIAGSin2017or2018.

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Gold Homogeneity in Certified Reference Materials… continued from page 1

CRMS SELECTED ToallowacomparisonbetweenCRMmanufacturesfour(4)auriferousgraderangeswerechosencentredaround0.5ppm;1ppm;3ppmand9ppm(seeTable2).TheselectionofCRMsfromthesegraderangesweredeterminedbytheavailabilityofmaterialsfromthemanu-facturers,andpreferencegiventoCRMsthataresiliceousinnatureandmanufacturedwithinthelastsixyears(tominimiseanyvariationduetochangeinthemanufacturingprocessand/orpossibleoxidationofsulphides).Tothisend,lowsulphursampleswerechosenwhereavailable.

ManufacturerMaterial grain size

Homogeneity testedLab list

providedStatistical metrics

ISO accreditation

Major and trace element data

AMIS < 54 umStated but details

not providedYes

SD, Between-lab SD, Within-Lab SD,

Combined Standard Uncertainty

YesMajors - certified; Traces - indicative

CDN < 53 um No Yes Between-lab SD NoMajors only -

indicative

Geostats < 75 um No NoSD, 95% Confidence

IntervalYes

Majors & Traces - indicative

OREAS < 30 μmYes (INAA

subsample method)Yes

SD, 95% Confidence limits, Tolerance limits

YesMajors & Traces -

indicative

RocklabsNot

specified

Yes (specific sampling/testing

regime incl segregation test)

YesBetween-lab SD, 95%

Confidence limitsNo

Majors only - indicative

Note: All manufacturers use multiple laboratory round robin for the certification process of gold by fire assay.

Table 1: Summary of attributes of the various manufacturer’s CRM as provided on their certificates.

•Fourx60gsachetsofeachofthefourCRMsfromOREASandreceivedinfoilpouches;

•One2.5kgplasticjarforeachCRMwereorderedandreceivedfromRocklabs.

ThematerialsasreceivedareshowninPhoto1.

Manufacturer CRMCertified Au (ppm)

Assay Method

Brief Material descriptionS

(%)SiO2

(%)Year of release

# labs

AMIS0352 0.45 Andesitic-dacite tuffaceous agglomerate 0.56 62.13 2012 23AMIS0310 1.03 Basalt, volcanics & granite 1.58 69.38 2012 17AMIS0360 2.94 BIF, mafic volcanics and sediments 6.46 48.05 2014 24AMIS0267 9.05 Qtz-carbonate-adularia 0.75 83.27 2012 19

CND-GS-P5C 0.571 Granitic 0.2 60.7 2014 15CND-GS-1M 1.07 Granitic 0.1 65.6 2013 15CND-GS-3L 3.18 Granitic 0.1 66.8 2013 15CND-GS-8C 8.59 Sourced from Cortez Hills Mine 0.6 56.6 2013 13

G909-6 0.57 Composite Gold Ores low sulphide nr nr 2009 132G313-1 1 Composite Mine Ore 0.035 64.56 2014 157G914-6 3.21 High Grade low sulphide ore 0.06 63.69 2015 179G914-7 9.81 High Grade low sulphide ore 0.04 60.87 2015 178

OREAS 201 0.514 Basaltic 0.39 53.69 2012 20OREAS 204 1.043 Basaltic 0.794 52.64 2012 20OREAS 17c 3.04 Basaltic 1.59 49.1 2009 18OREAS 62c 8.79 Andesitic volcanics 0.53 60.9 2009 16

SE68 0.599 2.3 54.76 2012 53SG66 1.086 2.6 54.52 2012 53SJ80 2.656 3 56.26 2013 54SN75 8.671 3.3 56.17 2013 54

nr = not reported

AMISFire

assay

CDN30 g Fire

assay

Feldspar, basalt & iron pyrites with minor fine gold minerals

Geostats50 g Fire

assay

OREAS30-50 g

Fire assay

Rocklabs30 g Fire

assay

Table 2: Summary of CRMs chosen for this study.

MATERIAL RECEIVED Amountscorrespondingtotheminimummanufacturersorderwerepurchased.Tothisend:•Twox100gsachetsofeachofthefourCRMwerepur-chasedfromAMISandreceivedinvacuumsealedfoilpouches;

•Fourx100gsachetsofeachofthefourCRMsfromCDNandreceivedinpaperbagsandsealedinplastic;

•Fourx100gsachetsofeachofthefourCRMsfromGeo-statsandreceivedinplasticbags;

ROCKLABS OREAS AMIS GEOSTATS CDN

Plate 1

Photo 1. CRM’s “as received” from the five manufacturers.

SAMPLE PREPARATION AND ANALYSIS Priortodispatchingthematerialsforanalysis,eachCRMwassubsampledtwentytimesinacleanroom.A10galiquotofeachCRMwasplacedintoaZiploc®plasticbagusingadisposableplasticspatulatoavoidanycrosscon-tamination.ThisprocedurewasrepeatedforeachCRMsothatthesamplesweresequencedinlotsof20,witheachlotcorrespondingtooneCRM. Forthehomogeneitytestwork,InstrumentalNeutronActivationAnalysis(INAA)wasused.INAAisahighlypreciseanduniqueassaymethodthatfocusesontheele-mentsnucleusirrespectiveofthesamplematrixorchemicalformoftheelement.Eachsampleissubjectedtoafluxofneutronstoproduceradioactivenuclides.Thesenuclidesdecayemittinggammaraysthatarecharacteristicforeachnuclide.Whencomparedwithaknownstandard,thein-tensityoftheemittedgammarayscanbequantifiedintoanelementconcentration(Lieser2001). The400x10gsubsamplesweredispatchedtoActiva-tionLaboratoriesLimited(Actlabs)inAncaster,Canada(www.actlabs.com)forINAA;Actlabswereinformedofthepurposeoftheanalysisandrequestedtoweighout1g

continued on page 6

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ofmaterialfromeachsample.Tominimiseanyeffectsofbetweenbatchbias,Actlabswererequestednottosplitanyofthe20sampleCRMlotsandallpossiblesourcesofmea-surementerror(e.g.,weighing,counting,detectorgeometry,fluxmonitorerrors,etc.)bekepttoaminimum.MinimisingthesourcesoferrorandensuringnosamplelotsweresplitprovidesconfidencethattheresultsareatruereflectionofCRMsamplingerrorsandhenceCRMhomogeneity,andthattheanalyticalprecisionerrorsareminorincompari-sontosamplingerrors.Bysubjectingallthesamplestotheidenticalnon-destructiveanalyticaltechniqueprovidedbyonelaboratorythatrequirednosamplepreparation,reagentsordigestion,anylaboratoryerrorisconstantforallsamplesandconsideredminimal.ThusvarianceinthespreadofanalyticalresultsfromeachoftheCRMswillrepresentthedegreeofhomogeneity.

RESULTS TheresultsofthisexercisearepresentedinAppendix1,whichisavailablefordownloadfromtheEXPLOREpageoftheAAGwebsite(www.appliedgeochemists.org).ThecertificatesoftheCRMsusedinthisstudyaredownload-ablefromtheAAGwebsite(www.appliedgeochemists.org)andtheGeochemicalServiceswebsite(http://www.gspty.com.au/).

Precision/homogeneity TheCertifiedValue(CV),RelativeStandardDevia-tion(RSDacrossthe20x1gINAAvaluesofeachCRM),

SamplingConstant(whichistheminimumrequiredsamplemasstoachievea1%RSD),meanINAAsamplemassanalysed(g),twoRelativeStandardDeviationsattypicalfireassaychargeweightsof30g(30g2RSD)and50g(50g2RSD)foreachCRMbymanufacturerispresentedinTable3.AmeanRSDforeachmanufacturerisalsopre-sentedasanindicationofoverallperformance.

Table 3. RSD Comparisons for the various CRM manufacturers (based on 20 x 1 gm INAA determinations per CRM).

Manufacturer CRMCertified

Value (ppm)

Mean INAA subsample

(g)

1 g RSD INAA

Mean RSDSampling

Constant (g)

30g 2RSD 50g 2RSDAMIS AMIS0352 0.450 1.05 4.48% 21.0 1.67% 1.30%

AMIS0310 1.03 1.06 12.80% 172.7 4.80% 3.72%AMIS0360 2.94 1.06 3.60% 13.7 1.35% 1.05%AMIS0267 9.05 1.05 27.46% 794.8 10.29% 7.97%

CDN CDN-GS-P5C 0.571 1.06 10.27% 111.8 3.86% 2.99%CDN-GS-1M 1.07 1.05 15.85% 263.4 5.93% 4.59%CDN-GS-3L 3.18 1.05 11.53% 140.0 4.32% 3.35%CDN-GS-8C 8.59 1.05 1.16% 1.4 0.43% 0.34%

Geostats G909-6 0.570 1.06 2.93% 9.1 1.10% 0.85%G313-1 1.00 1.04 6.14% 39.4 2.29% 1.78%G914-6 3.21 1.06 2.15% 4.9 0.81% 0.63%G914-7 9.81 1.05 1.15% 1.4 0.43% 0.33%

OREAS OREAS 201 0.514 1.06 1.87% 3.7 0.70% 0.54%OREAS 204 1.04 1.05 1.77% 3.3 0.66% 0.51%OREAS 17c 3.04 1.05 1.61% 2.7 0.60% 0.47%OREAS 62c 8.79 1.04 1.18% 1.4 0.44% 0.34%

Rocklabs SE68 0.599 1.06 1.90% 3.8 0.71% 0.55%SG66 1.09 1.06 5.05% 27.1 1.90% 1.47%SJ80 2.66 1.05 1.20% 1.5 0.45% 0.35%SN75 8.67 1.04 1.26% 1.7 0.47% 0.36%

NOTE: Sampling Constant is the required grams to achieve a 1% RSD.

Based on 1 gm INAA data and the Sampling

Constant

12.08%

3.09%

1.61%

2.35%

9.70%

Table 3: Relative Standard Deviation comparison for the various CRM Manufacturers (based on 20 x 1 g INAA determinations per CRM).

TheRSDisusedasastandardisedmeasureofdisper-sionthatindicatestheprecisionorrepeatabilityofanassay.ThelowertheRSD,themorerepeatable,preciseorhomo-geneoustheCRM;converselythehighertheRSDthelesshomogeneoustheCRM.GiventhecriticalimportanceofCRMsandtheirmandatoryuseintheminingandexplora-tionindustry,thelowertheRSDdeterminedfromrepli-cateanalysisviatheINAAmethodonreducedanalyticalsubsamples(e.g.1g)themorehomogenousthereferencematerialandthegreaterconfidenceandcontroltheQCofficerhasinvettingdataqualityfromalaboratory.TheoverallmeanRSDforeachmanufacturerhasbeenderivedfromthemeanoftheindividualRSD’softhe1gINAAdata.InorderofincreasingmeanRSD(correspondingtodecreasinghomogeneity)theyrangefromOREAS:1.61%,toRocklabs:2.35%,toGeostats:3.09%,toCDN:9.70%,toAMIS:12.08%. TheSamplingConstant(Ingamells&Switzer1973)hasbeencalculatedtoshowtheminimumsamplemassrequiredtomeasuregoldineachCRMbythe1gINAAmethodtoachievearelativestandarddeviationof1%.Forhighgradegoldsamples(~9ppmAu),thesamplingconstantrangesfromalowof1.4gfromCDN,GeostatsandOREASto794.8gforAMIS.ThissuggestsAMIS0267isinfluencedbyanuggeteffect. The30and50g2RSDshavebeencalculatedfromtheSamplingConstantsforeachCRMandinsomeinstances


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revealsignificantsamplingerrors.Typicalmeasurementerrorfor30or50gfireassaychargeweightsareusu-allyaround5%atcommerciallaboratoriesfororegrademethods.The2RSDvaluesencapsulatethesamplingerrorcontributionfromtheCRMandthesecanbeaddedtothenominal5%measurementerrorlaboratoriestendtoachievetogetafeelforwhattheoverallerrorswouldbeinreportedanalyticalresults.Resultsfromindividualmanu-facturersarediscussedbelow:

AMIS:homogeneityforindividualAMISCRMsvariesfrom3.60%RSD(AMIS0360;2.94ppmAu)to27.46%RSD(AMIS0267;9.05ppmAu),aspreadof23.86%RSDshow-ingnosystematicchangeinhomogeneitywithchanginggrade.ThesamplingconstantforAMIS0267indicatesthat794.8gofsamplewouldberequiredtoensureaRSDof1%duringanalysis,andfora30gfireassayasamplingerrorof10.29%applies.AtthischargemassonlyAMIS0352(30g2RSDsamplingerrorof1.67%)andAMIS0360(30g2RSDof1.35%)wouldbefitforpurposeCRMsbasedonthesecalculations.ThegoldhomogeneityofCRMsproducedbyAMISisconsideredverypoortogood.

CDN:homogeneityforindividualCDNCRMsvariesfrom1.16%RSD(CDN-GS-8C;8.59ppmAu)to15.85%RSD(CDN-GS-1M;1.07ppmAu),aspreadof14.69%RSDshowingnosystematicchangeinhomogeneitywithchang-inggrade.OfthefourCRMsevaluatedonlyCDN-GS-8C(30g2RSDof0.44%),thehighestgradeCDNgoldCRMtested,wouldbesuitablefora30gfireassay.ForCDN-GS-P5C(0.571ppmAu)asamplemassof111.8gwouldberequiredtoobtainanRSDof1%duringanalysis;equiva-lenttoasamplingerror(30g2RSD)of3.86%;263.4gforCDN-GS-1M;equivalenttoa2RSDsamplingerrorof5.93%at30g;and140.0gforCDN-GS-3L(3.18ppmAu),equivalenttoa2RSDsamplingerrorof4.32%at30g.WhilethehomogeneityofCDN-GS-8Cisverygood,theremainingCDNCRMstestedareconsideredtobepoortoverypoor.

Geostats:homogeneityforindividualGeostatsCRM’svaryfrom1.15%RSD(G914-7;9.81ppmAu)to6.14%RSD(G313-1;1.00ppmAu),aspreadof4.99%RSDshowingnosystematicchangeinhomogeneitywithchanginggrade.ThreeofthefourCRM’s(G909-6at0.570ppmAu,G914-6at3.21ppmAu&G914-7at9.81ppmAu)arefitforpurposeasgradecontrolCRM’sfor30gfireassaywhilstG313-1at1.00ppmAuwouldbesuitablefora50gfireassaybasedonthesamplingconstant.The2RSDsamplingerrorsata30gchargeweightvaryfrom0.43%to2.29%.ThehomogeneityofCRM’sproducedbyGeostatsrangefrommediocretoverygood.

OREAS:AllOREASCRM’sshowconsistentlylowRSDsrangingfrom1.18%RSD(OREAS62cat8.79ppmAu)to1.87%RSD(OREAS201at0.514ppmAu)foraspreadof0.69%RSD.AninversecorrelationisapparentbetweengradeandRSDsuggestingapossibleinfluenceofanalytical

precision.AllfourOREASCRM’stestedarefitforpur-posefor30gfireassaywithsamplingconstantsindicatingthata4gfireassaychargeweightwouldprovideasamplingerrorof1%orlessforallOREASCRM’s.Thesamplinger-rorata30gchargeweightvariesfrom0.44%to0.70%.ThehomogeneityofCRM’sproducedbyOREASisconsideredverygood.

Rocklabs:IndividualRocklabsCRMhomogeneityvariesfrom1.20%RSD(SJ80at2.66ppmAu)to5.05%RSD(SG66at1.09ppmAu),aspreadof3.83%RSDwiththeCRM’sshowingnosystematicchangeinhomogeneitywithchanginggrade.ThreeofthefourCRM’s(SE68at0.599ppmAu,SJ80at2.66ppmAuandSN75at8.67ppmAu)arefitforpurposefor30gfireassaywhileSG66wouldprobablybemorefitforpurposefor50gfireassaybasedonthesamplingconstant.Thesamplingerrorsofa30gchargeweightrangefrom0.45%to1.90%.ThehomogeneityofCRM’sproducedbyRocklabsisconsideredgoodtoverygood.

Manufacturer CRMCertified Value Au

(ppb)NAA Mean Au

(ppb)NAA Min Au

(ppb)NAA Max Au (ppb)

NAA SDev Au (ppb)

AMIS0352 450 445.3 393 467 20AMIS0310 1030 1080 946 1450 138AMIS0360 2940 3014 2810 3280 109AMIS0267 9050 8849 7450 17900 2425

CDN-GS-P5C 571 492.7 423 642 51CDN-GS-1M 1070 975.4 774 1480 155CDN-GS-3L 3180 3136 2340 3800 365CDN-GS-8C 8590 8238 8100 8440 96

G909-6 570 545.8 510 576 16G313-1 1000 971.8 885 1130 60G914-6 3210 3269 3110 3390 70G914-7 9810 9657 9440 10000 112

OREAS 201 514 546.2 531 567 10OREAS 204 1043 1020 990 1050 18OREAS 17c 3040 3009 2940 3110 48OREAS 62c 8790 8411 8100 8570 99

SE68 599 615.5 591 638 12SG66 1086 1087 1030 1300 55SJ80 2656 2520 2450 2570 30SN75 8671 8000 7720 8150 100

AMIS

CDN

Geostats

OREAS

Rocklabs

Table 4: Summary Statistics for each CRM.

INTERNAL CRM VARIATION Control charts presented below show the variation inresultsof eachCRMforeachmanufacturer. Figures1 to5(A-Dplots)showgraphicalrepresentationofthe20x1gINAAdatawheretheXaxisrepresentstheorderofanalysis(analyticalsubsamples1to20)fromlefttoright;andtheYaxisshowsthemeasuredINAAconcentrationinAuppb.AsolidredlineshowsthemeanINAAvalue(seeTable4)foreachCRMandforeachgraderange(i.e.0.5ppmAu,1ppmAu,3ppmAuand9ppmAu).ThesameYaxisconcentra-tionrangeandscalehasbeenusedwherepossibletofacili-tate visual comparison between themanufacturers. TheYaxisinFigures1-5(E-Hplots)showsthepercentagediffer-encefromthecalculatedINAAmean.ThesediagramsarenotintendedasverificationchartsforeachCRMbyINAA,butasastandardisedgraphicalcommunicationtool.





AMIS: Figure 1 graphically depicts results for the AMISCRMs. Individual values for each CRM show a widespreadofalmostrandomdatawithnosystematicvariation.AMIS0267(cert9.05ppm)rangesfrom7.45ppmAuto17.90ppmAu(Fig.1D)whichrepresents-15.8%to+102%dif-ferencefromtheINAAmeanofthisCRM(Fig.1H).Two

43.5% 102%

29.7% 34.2%

Au (p

pb)

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Figure 1 samplesshowasignificantdeparturefromtheINAAmean,reporting+43.5%(12.70ppmAu)and+102%(17.90ppmAu)ofthemeanvalue(Fig.1H)andreflects inhomogene-ity (presumably a nugget effect) of theCRM. AMIS0310(cert1.03ppm)alsoshows(Figs.1BandF)significantde-parturefromtheINAAmeanfortwosamples(+29.7%and

Figure 1. Control charts for AMIS CRMs showing INAA concentration (Au ppb) in relation to the certified value [A-D] and the percentage difference from the INAA mean value [E-H].




+34.2%). This inhomogeneityofAMISCRMshaspoten-tiallysignificantimplicationsforlaboratoryreportingwhere-byauserwouldquestionthelaboratoryresultsbasedontheassumptionthattheCRMishomogeneous.

CDN:Figure2graphicallydisplaystheresultsfortheCDN

-25.4%

-20.6%

51.7%

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pb)

Order of analysis

Au (p

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%ag

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age

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n NA

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30.3%

21.7%

Figure 2 CRMs.WiththeexceptionofCDN-GS-8C(cert8.59ppm)whichhasaverytightspreadofdataaroundtheINAAmeanrangingfrom-1.7%to+2.5%(Fig.2H).ThelowerthreeofthefourCDNCRMs(CDN-GS-P5C,CDN-GS-1MandCDN-GS-3L),showawidescatterofdatathatcom-monlyexceeds±20%oftheINAAmeanvalue;CDN-GS-

Figure 2. Control charts for CDN CRMs showing INAA concentration (Au ppb) in relation to the certified value [A-D] and the percentage difference from the INAA mean value [E-H].



P5C(cert.0.571ppm)showsarangeof-14.2to+30.3%fromtheINAAmean(Figs.2Aand2E);CDN-GS-1M(cert1.07ppm)rangesfrom-20.6to+51.7(Figs.2Band2F)andCDN-GS-3L(cert3.18ppm)rangesfrom-25.4to+21.2%(Figs.2C&2G).ThisindicatesinhomogeneityinthreeoftheseCRMsproducedbyCDN.Theexceptionis

Au (p

pb)

Order of analysis

Au (p

pb)

Au (p

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Figure 3 continued on page 13

Figure 3. Control charts for Geostats CRMs showing INAA concentration (Au ppb) in relation to the certified value [A-D] and the per-centage difference from the INAA mean value [E-H].

CDN-GS-8C(cert8.59ppm)whichhasaverytightspreadofdataaroundtheINAAmeanrangingfrom-1.7%to+2.5%(Figs.2Dand2H).

GEOSTATS:Figure3showstheindividualresultsfortheGeostatsCRMs.G914-6(cert3.21ppm)andG914-7(cert



Gold Homogeneity in Certified Reference Materials… continued from page 12Au

(ppb

)

Order of analysis

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Figure 4 9.81ppm)showarelativelytightclusteraroundtheINAAmeanwithG914-6rangingfrom-4.9%to+3.7%(Figs.3Eand3G)andG914-7-rangingfrom-2.2to+3.6%(Figs.3DandH).G909-6(cert0.57ppm)showsawiderscatterwhilstG313-1(cert1.0ppm)showsthewidestscatterof

allGeostatsCRMsrangingfrom-8.9%to+16.3%oftheINAAmean(Figs.3Band3F). OREAS:Figure4showstheindividualresultsfortheOREASCRMs.AllOREASCRMsshowaconsistent

Figure 4. Control charts for OREAS CRMs showing INAA concentration (Au ppb) in relation to the certified value [A-D] and the percent-age difference from the INAA mean value [E-H].



tightrangewithin±5%oftheINAAmeanindicatingaconsistenthomogenousCRMproductovertherangeofCRMstested. Rocklabs:Figure5showstheindividualresultsforthe

Au (p

pb)

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Figure 5 Figure 5. Control charts for Rocklabs CRMs showing INAA concentration (Au ppb) in relation to the certified value [A-D] and the per-centage difference from the INAA mean value [E-H].


RocklabsCRMs.ThreeofthefourCRMsevaluatedshowatightrangewithin±5%oftheINAAmeanindicatingaconsistenthomogenousproduct.SG66(cert1.086ppm)isslightlylesshomogenouswithvaluesrangingfrom-5.2%to+19.6%includingoneoutlier(Figs.5Band5F).



DISCUSSION TheapplicationofCRMsintheminingandexplora-tionindustryistomonitorlaboratoryqualityandtocomplywithmandatoryreportingrequirements(e.g.,TSX,ASX).Theyarealsoutilisedduringorereservecalculationstoun-derstandtheuncertaintyinaresourcethatultimatelyfeedsintoaneconomicmodel.ItisthusessentialthatusershaveconfidenceinthequalityandhomogeneityoftheirCRMs.TheCRMcertifiedvaluesareconsensusvaluesderivedbyinter-laboratoryroundrobinprograms.Themethodsusedbysomemanufacturerstofilteroutlierscanmaskpotentialissueswiththehomogeneityofthematerials.Onlyoutliersconfidentlyreasonedtobeanalyticalshouldberemovedandthisconfidenceonlyexistswherehomogeneityhasbeenindependentlyvalidated. Resultsfromthisstudyshowthatthedegreeofhomo-geneityofCRMsavailablefromthefivemanufacturersisvariable;usersandanalystsofthesematerialsneedcon-fidencethattheCRMsarehomogenoustoalevelfitforpurposesothatQCfailuresaregenuineandnotafunctionofsamplingerror(i.e.inhomogeneousmaterials).Arank-ingsystembasedonthevaluesforthe30g2RSDsamplingerrorwouldprovideaguidetohomogeneityofaCRMandenableuserstoselectappropriateCRMsfortheirprojectssuchthat<1%isconsideredVeryGood;1-2%consideredGood;2-3%consideredMediocre;3-4%consideredPoorand>4%consideredVeryPoor. AMIS(McWha&Smee2012a-c,2014)certificatescontainnoevidenceofhomogeneitytestingbutstate,“Sampleswererandomlyselectedforhomogeneitytestingandthirdpartyanalysis.Statisticalanalysisofbothhomo-geneityandtheconsensustestresultswerecarriedoutbyindependentstatisticians”.CDNcertificates(Sanderson&Smee2013a-c,2014)makenomentionofhomogeneity;Geostatscertificates(Geostats2009,2014,2015a,b)pro-videanunsupportedstatementthat“materialsaretestedregularlytoensurestabilityandhomogeneity”.OREASpublisheshomogeneitytestresultswiththeirgoldCRMcertificates(Hamlyn,2009a,b,2012a,b).Rocklabs(Smith&Ball2012a,b,2013a,b)certificatescontaina‘Homogene-ityAssessment’sectionwiththeRSDreportedbutdonotprovidetheactualresults.Segregation/Settlinginformationisalsoprovided. ToenabletheexplorationandminingindustrytohaveconfidenceinthequalityofgoldCRMsusedforQCandmandatoryreporting,manufacturersneedtoprovidedataonthehomogeneityofeverygoldCRM.Thishomogene-itytestworkcouldbethroughtheReducedAnalyticalSubsampleMethodasutilisedroutinelybyOREASandchosenforthisstudyorthroughtheReplicatesofLargeandSmallSampleMassasdescribedbyBagleyetal.(2015).WithoutCRMmanufacturersprovidingtranspar-encyonthehomogeneitythroughtestwork,usersshouldnotassumeallCRMsrepresentqualityproducts.

CONCLUSIONS ThehomogeneityoftwentycommercialgoldoreCRMsproducedbyAMIS(SouthAfrica),CDN(Canada),

Geostats(Australia),OREAS(Australia)andRocklabs(NewZealand)havebeenevaluatedandcompared.TheCRMsrangeingoldcontentfrom0.45to9.81ppm,typicalofthelevelscommonlyencounteredinminingexplorationprojects. TheCRMsofAMIS,CDN,GeostatsandOREASareproducedfromnaturallyoccurringgoldorestowhichvariablequantitiesofbarren/wasterockmaterialhasbeenaddedtoachievetargetgrades.RocklabsCRMsarepro-ducedfromarangeofrockandmineralproductstowhichfinegolddustparticleshavebeenaddedinconcentrationstoachievedesiredgrades. Theinvestigationhasshownaremarkablecontrastinhomogeneitybetweenthevariousproducers.Thesecon-trastinglevelsofhomogeneityhaveseriousramificationswithregardtosamplingerrors,whichinsomeinstancesareofamagnitudeequaltoorgreaterthantypical30gfireassaymeasurementerrorsrenderingthemofquestionablevalueasaQCtool.Samplingerrorsforatypicalfireassaychargeweight(25to50g)shouldbeveryminorcomparedtolaboratorymeasurementerrors.OtherwisetheCRMcannotbedeemedfitforpurposeastheuserisunableascertainthesourceoftheerrorseeninanalyticaldata. Thehomogeneityofthe20goldCRM’swereevalu-atedusingtheSamplingConstant,theminimumsamplemass(chargeweight)requiredtoachievea1%relativestandarddeviationinrepeatanalyses.ForthefourAMISCRM’stested,theSamplingConstantsreturnedarangefrom14to791g.CDNhadoneCRMwithaSamplingConstantof1.4gwhiletheotherthreerangedfrom111.8to263.4g.GeostatshadoneCRMwithaSamplingCon-stantof1.4gwiththeotherthreerangingfrom4.9to39.4g. TheOREASCRM’sallreturnedSamplingConstantsoflessthan4g.ForRocklabs,threeofthefourCRM’sre-turnedSamplingConstantsoflessthan4gwiththefourthcominginat27.1g.Currently,OREASistheonlyCRMmanufacturerroutinelyevaluatingandpublishingtheresultsofhomogeneitytestworkonalltheirgoldCRM’susingtheReducedAnalyticalSubsampleINAAmethod. ThisstudyclearlydemonstratesthatthereisawiderangeinqualityamongstcommerciallyavailablegoldoreCRM’sandthatthehomogeneityofgoldCRM’sfrommostmanufacturersvariesfromoneproducttothenext.ItisproposedthatallmanufacturersbeencouragedtoundertakeandpublishresultsofhomogeneitytestworkongoldinCRM’s,therebyprovidingendusersirrefutabledataonthemagnitudeofCRMsamplingerrorsandtheirimpactonQCprotocols.

ACKNOWLEDGEMENTS AND DISCLOSURE TheauthorwouldliketoacknowledgetworeviewerswhoassistedinframingthisarticleandRobertGarrett,EmeritusScientist,GeologicalSurveyofCanada,forhisconstructivecommentsonthemanuscript.Theauthorhasnofinancialinterests,directorindirect,inanyofthefiveCRMmanufacturers.




REFERENCES

Bagley,T.,Stanley,C.R.andMurimboh,J.2015.Deter-miningtheheterogeneityofReferenceMaterials.Pro-ceedingsofthe27thInternationalAppliedGeochemistrySymposium,April20-24,2015,Tucson,USA,9p.

GeostatsPtyLtd.2009.CertifiedGoldReferenceMaterialProductCodeG909-6.GeostatsPtyLtd.,1p.

GeostatsPtyLtd.2014.CertifiedGoldReferenceMaterialProductCodeG313-1.GeostatsPtyLtd.,1p.

GeostatsPtyLtd.2015a.CertifiedGoldReferenceMate-rialProductCodeG914-6.GeostatsPtyLtd.,1p.

GeostatsPtyLtd.2015b.CertifiedGoldReferenceMate-rialProductCodeG914-7.GeostatsPtyLtd.,1p.

Hamlyn,C.2009a.CertificateofAnalysisforGoldRefer-enceMaterialOREAS17c.OreResearchandExplorationPtyLtd.,10p.

Hamlyn,C.2009b.CertificateofAnalysisforGold-SilverReferenceMaterialOREAS62c.OreResearchandExplo-rationPtyLtd.,12p.

Hamlyn,C.2012a.CertificateofAnalysisforGoldOreReferenceMaterialOREAS201.OreResearchandEx-plorationPtyLtd.,7p.

Hamlyn,C.2012b.CertificateofAnalysisforGoldOreReferenceMaterialOREAS204.OreResearchandEx-plorationPtyLtd,7p.

Ingamells,C.O.&Switzer,P.1973.Aproposedsamplingconstantforuseingeochemicalanalysis.Talanta,20,547-568.

JORC.2012.AustralasianCodeforReportingofExplora-tionResults,MineralResourcesandOreReserves(TheJORCCode)[online].Availablefrom:(TheJointOreRe-servesCommitteeofTheAustralasianInstituteofMiningandMetallurgy,AustralianInstituteofGeoscientistsandMineralsCouncilofAustralia),44p.

Lieser,K.H.2001.Nuclear and Radiochemistry,2ndEd.:JohnWiley&Sons,Inc.

McWha,M.&Smee,B.W.2012a.AMIS0267,CertifiedReferenceMaterial,Goldsilver,epithermalveinore(highgrade)Guanajuato,Mexico.AfricanMineralStandards,11p.

McWha,M.&Smee,B.W.2012b.AMIS0310,CertifiedReferenceMaterial,GoldandCopperore,greenstone(rougherfeed)BuzwagiMine,Tanzania,AfricanMineralStandards,9p.

McWha,M.&Smee,B.W.2012c.AMIS0352,CertifiedReferenceMaterial,Mediumgradeepithermalgoldore,MasbateGoldProject,Philippines.AfricanMineralStan-dards,9p.

McWha,M.&Smee,B.W.2014.AMIS0360,CertifiedReferenceMaterial,Goldore,TaylorsMine,BarbertonGreenstoneBelt,SouthAfrica,10p.

NI43-101.2011.Standardsofdisclosureformineralproj-ects(Ni43-101);Chapter5,RulesandPolicies,CanadianInstituteofMining,MetallurgyandPetroleum,7043-7086,(http://web.cim.org/).

SAMREC.2009.TheSouthAfricanMineralCodefortheReportingofExplorationResults.MineralResourcesandMineralReserves(TheSAMRECCode),2007EditionasamendedJuly2009,61p(http://www.samcode.co.za/).TheSouthAfricanInstituteofMiningandMetallurgy(SA-MIM);GeologicalSocietyofSouthAfrica(GSSA).

Smith,M.&Ball,T.2012a.CertificateofAnalysisROCK-LABSReferenceMaterialSE68.Rocklabs,6p.

Smith,M.&Ball,T.2012b.CertificateofAnalysis.ROCK-LABSReferenceMaterialSG66.Rocklabs,6p.

Smith,M.&Ball,T.2013a.CertificateofAnalysis.ROCK-LABSReferenceMaterialSJ80.Rocklabs,6p.

Smith,M.&Ball,T.2013b.CertificateofAnalysis.ROCK-LABSReferenceMaterialSN75.Rocklabs,6p.

Sanderson,D.&Smee,B.W.2013a.ReferenceMaterials:CDN-GS-1M.CDNResourcesLaboratoryLtd.,2p.

Sanderson,D.&Smee,B.W.2013b.ReferenceMaterials:CDN-GS-3L.CDNResourcesLaboratoryLtd.,2p.

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Stanley,C.R.&Smee,B.W.2007Strategiesforreducingsamplingerrorsinexplorationandresourcedefinitiondrillingprogrammesforgolddeposits.Geochemistry: Ex-ploration, Environment, Analysis,7,329–340.


Geochemical Nuggets *New Feature*Sometimes an ICP-MS Never Forgets!

Table 1. Gold analyses by ICP-MS following an aqua regia diges-tion, with a lower detection limit of 0.1 ppb and an upper detec-tion limit of 100 ppb.

Asageneralrule,itisalwaysagoodideatomatchboththematrixandgrade

ofcertifiedreferencematerials(CRM)withthesamplesinageochemicalsurvey.Thefollowingexampleillustrateswhatcanhappenwhenthisisnotthecase. Table1illustratesasub-sampleofICP-MSaquaregiaAudataforsoilsamplesinaregionalsurveydesignedtodetectsub-10ppbAuanomalies.Thecontrolmaterialchosenforthesurveywasasulphidic,oregradeAuCRMbecausethisiswhattheexplorationcrewhadonhand.Asthetableillustrates,regionalbackgroundisprobablyontheorderof2ppb,sotheCRMchosenwasmorethanthreeordersofmagnitudeabovethislevel.ThehighlevelsofAuintheCRMhavecarriedacrosstothe“downstream”sampleswithintheanalyticalsequence,givingthemvaluesthatwouldotherwisebeconsideredanomalous.Theeffectpossiblycontinuesfurtheralongtheanalyticalsequencealthoughthelevelofcontaminationgraduallydiminishes.Asaconsequence,themostobviouslyaffectedsampleshadtobefilteredoutoftheinterpretationofasurveyinvolvingseveralhundredsoilsamples. The“memoryeffect”isawell-knownissuewithanaly-sesbyconventionalICP-MSusinganaquaregiadigestion(WangandBrindle,2014),orevenun-acidifiedsamples.Es-sentially,metalsmaybeadsorbedfromsolutionontoglasswareortubingduringsampleinjectionandnebulizationwithinanICP.Thesemetalsmaynotbeeffectivelyremovedbystandard,diluteacidicwashsolutionsanditmaybesometimebeforecrosscontaminationlevelsarereducedtobackgroundlevels,aswasthecasehere.Hadtheissuebeenrecognizedintime,thesamplesolutionsmighthavebeenre-readbeforedisposal,withouttheCRMs. Whileadvancesininstrumentationnowallowustode-tectthelevelsofsomeanalytesdowntotheppborevenpptlevel,theseadvancesmustbematchedwithanunderstand-ingofinstrumentationandtheconsequencesoffailingtouseappropriateCRMs.Inthisinstanceawell-intentionedattempttointroducequalitycontrolssamplesintoalow-levelAusoilsurveysucceededonlyincompromisingthedataduetopoorCRMselection.

References

Wang,Y.&Brindle,I.D.2014,Rapidhigh-performancesampledigestionforICPdeterminationbyColdblockTMdigestion:part2:golddeterminationingeologicalsampleswithmemoryeffectelimination.Journal of Analytical Atomic Spectrometry,29,1904-1911.

Join us for Exploration ‘17October 21-25, 2017, Toronto, Ontario, Canada

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Decennial Conference Proceedings from the past five conferences (1967, 1977, 1987, 1997, 2007) are available for download on the web site under the ‘Resources’ header.

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Minutes of the 2015 AAG Annual General Meeting

Minutesofthe2015AnnualGeneralMeetingoftheAs-sociationofAppliedGeochemists,heldatthe27thInterna-tionalAppliedGeochemistrySymposium,Tucson,Arizona,USA,20April2015

I. Call to Order – Establishment of Quorum PresidentLeybournecalledtheAnnualGeneralMeet-ing(AGM)toorderat6:00PMlocaltime.Morethan30AAGFellowswerepresent,exceedingthenecessary15requiredforaquorum.

II. President’s report (M. Leybourne) PresidentLeybournethankedtheAAGExecutive,Council,andRegionalCouncilorsfortheircontributionstoAAGduringthetimesincethe2014AGM.HeextendedaspecialthankyoutoGwendyHallforhertremendouscontributiontoAAGasEditorofGEEAsinceitsinception(Volume1,Number1beingpublishedinFebruary2001)to2015.HealsowelcomedKurtKyserasthenewEditorofGEEA.HethankedBethMcClenaghan(Editor)andPimvanGeffen(BusinessManager)fortheircontributionstotheAAGnewsletterEXPLORE.HealsoextendedthankstoPatricedeCaritatforservingasAAG’sliaisonwithEle-mentsmagazineforthepastfewyearsandannouncedthatDennisArnewouldbetakingoverthoseresponsibilities.BrunoLemièreandGemmaBonham-Carterwererecog-nizedfortheiroutstandingcontributionstoAAG’swebsiteandAlArseneaultforhisdedicationtoAAGastheAs-sociation’sBusinessManager.Lastly,PresidentLeybournethankedErickWeiland,RobBowell,SarahLincoln,andRickSchwarzfortheirhardworkastheLocalOrganizingCommitteeforthe27thInternationalAppliedGeochemis-trySymposium. PresidentLeybourneannouncedthatDanielLayton-MatthewsofQueen’sUniversity,Kingston,Ontario,Cana-da,willbeAAG’sDistinguishedLecturerfor2015–2016.

III. Vice President’s report (R. Noble) VicePresidentNoblereportedonprogressinthepubli-cationofBobBoyle’sbookonthehistoryofgeochemistryandcosmochemistry.AneditorialteamisnowinplaceanditishopedthisbookmightbereadyforthenextIAGSin2017. Duringthisyear,AAGhasreceivedthreeupdatesfromRegionalCouncilors.NealBrewardhassteppeddownasRegionalCouncilorfortheUKandRepublicofIreland.VicePresidentNobleextendedhisthankstoNealforhisservicetotheAssociation.

VicePresidentNoblerecognizedPeterBradshawwhoreportedonprogressofthebookaboutthecontributionsofTonyBarringertothefieldofgeochemistry.Thefirstdraftislargelyeditedandthefirsttwochaptershavebeenprintset.Whencomplete,thebookwillbeavailableforpurchaseontheAAGwebsite. Lastly,VicePresidentNobleannouncedthatSteveCookwillbeAAG’snewVicePresidentbeginninginJanu-ary2016.

IV. Treasurer’s report (G. Hall) In2014,AAGsuccessfullyaccomplishedallthepaper-worknecessarytocontinueitsnon-profitstatusunderthenewCanadaNot-for-ProfitCorporationsAct. Ourinvestmentholdingsat3MacsforMarch31,2015:$615,301.29inCdn$(7%ofthatiscash)and$89,514.85inUS$cash(soontobeinvested). AlsoasofMarch31,ouraccountsare: CIBCCdn $25,539 CIBCUS $15,303

V. GEEA (G. Hall) AAG’sshareoftheprofitfromGEEAfor2014wasUS$43,797.Therejectionrateforsubmittedmanuscriptsisabout64%.

VI. EXPLORE (B. McClenaghan and P. van Geffen) B.McClenaghanthankedallthecorporatesponsorsandadvertisersforEXPLORE.In2014,welostonecorpo-ratesponsor.Thenewsletteroperatedatasmallprofitin2014.

VII. Awards and medals (B. Eppinger) ColinDunn(2014)andRaviAnand(2015)willbereceivingAAG’sGoldMedalduringtheIAGS.BethMc-ClenaghanwillbereceivingtheSilverMedal.Requestsfornominationsfor2016willbesenttoAAGmemberssoon.

VIII. Symposia (D. Cohen) Thebidtoholdthe2017IAGSinFlorence,ItalywasrejectedbyCouncilbecauseofconcernsaboutsomeofthecostestimates.TheAssociationiscurrentlyinvestigatingholdingthe2017IAGSinCanada.Moreinformationwillbeavailableinthenextfewmonths.

IX. Other business PresidentLeybourneopenedthemeetingtoquestionsfromtheattendingAAGFellows.Avarietyoftopicswerediscussedthatwererelatedtoothersectionsoftheminutesandconcluded.

X. Adjournment PresidentLeybournethankedalltheparticipantsforattendingthe2015AGManddeclaredthemeeetingad-journedat6:47PMlocaltime.

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Recently Published in ElementsVolume 11, no. 4 Social and Economic Impact of Geochemistry TheAugusteditionofElementsfocusedonthemanywaysthatappliedgeochemistryimpactssociety.Itstartswithanoverviewoftheimpactofgeochemistry(Ludden,Albarède&Coleman),looksathowgeochemistryisusedinmineralexploration(Kyser,Barr&Ihlenfeld)andthenatnewchallengesandmaterialsinthefieldofenvironmentalmineralogy(Calas,McMillan&Bernier-Latmani).AnarticlebasedonacasestudyfromtheCityofLondonexamineshowgeochemistrycanbeappliedtourbanplanning(Ludden,Peach&Flight),whilstanotherexplorestheuseofstableisotopesinforensicgeochemistry(Ehleringer,Chesson,Valenzuela,Tipple&Martinella).Thefinalcontributionexplorestheusesofmetalstableisotopesinmedicine(Rakovan&Pasteris).TheAAGSocietyNewsincludedasummaryofthesuccessful27thIAGSbyErickWeilandandanabstractofBobGarrett’sthought-provokingarticleonQA/QCplotsthatappearedinExplore167.Therecertainlyshouldbesomethingfornearlyeverygeochemistinthisvol-ume!

Volume 11, no. 5, Supergene Metal Deposits TheOctobereditionofElementsfocusesonsupergenemetaldeposits.Itbeginswithanoverviewofthegeologicalandeconomicsig-nificanceofsupergenemetaldeposits(Reich&Vasconcelos),exploressupergenealterationoforedeposits(Dill),paleoclimaticsignaturesofthisdeposittype(Vasconcelos,Reich&Shuster),theuseofCuisotopesinunderstandingsupergeneprocesses(Mathur&Fantle),predictinggeologicalcorrosionwithelectrodes(Renock&Shuller-Nickles),andfinisheswithanexaminationofthegeomicrobiologyofsupergenemetaldeposits(Zammit,Shuster,Gagen&Southam).TheAAGSocietyNewsincludedashortobituaryforEricHoffman,aswellascitationsforthewinnersofthe2014and2015goldandsilvermedals.Thisiscertainlyanissueforthoseinvolvedinregolithgeochemistryandwithaninterestinsupergenemineraldeposits.

Dennis Arne

InlovingmemoryofDr.EricHoffman,Ph.D,P.Geo,theEricL.HoffmanMemorialScholarshiphasbeenes-tablishedattheUniversityofToronto,Canada.ThisEarthSciencesgraduatescholarshipwillbeabletohelpfuturestudentsadvanceafieldthatEricwassopassionateabout.Dr.EricHoffmanwasthePresidentandfounderofActi-vationLaboratoriesLtd.(Actlabs),withheadquartersinAncaster,Ontario,Canada,specializingincontractanalyti-calservicestomanyindustriesincluding;Minerals,Metal-lurgy,Petroleum,LifeSciences,Environmental,Forensics,MaterialsTesting,andAgriculture.EricdedicatedhiscareertoadvancingActlabsandthegeochemicalfieldandquicklybecamearespectedandvaluablecontributortothegeochemistrycommunity.Ericwasastrongsupporterofcollaborativeindustry-Universityresearchsupporting

bothundergraduateandgraduatestudentswhileprovidingprojectguidanceandcontributingtohundredsofresearchpublications. Eveninhisabsence,Actlabswillcontinuetoprovideindustry-leadinginnovativetechnologiesandhighqual-ityservicesandsupportstudentsthroughActlabsandtheEricL.HoffmanMemorialScholarship.Eric’smemorywillneverbeforgottenandhislegacywillliveforever. Tocontributetothescholarship,visitthewebpageontheUniversityofTorontowebsite:

https://donate.utoronto.ca/give/show/85 IfyouhaveanyquestionsregardingtheMemorialScholarshiporhavememoriesorcommentsaboutEricthatyouwouldliketoshare,contact:[email protected]

Eric L. Hoffman Memorial Scholarship


AAG’s Student Support Program Resurrected in 2015

Treatise on Geochemistry. Edition No. 2

Researchcarriedoutbystudentsofappliedgeochemis-tryusuallyinvolvesgeochemicalanalysis,thecostofwhichcanbeonerous.Recognisingthisfact,theAssociationofAppliedGeochemists(AAG)institutedaStudentSupportProgramin2011,inwhichanalyticallaboratoriesofferedsupporttoappliedgeochemistrystudentsintheformoffreeanalyses.ThisprogramhasbeenimplementedbytheAAGforovertwoyears.Duetothedownturninthemineralexplorationsector,participatinglaboratorieswerenotbe-ingabletosustaintheirinvolvementandtheprogramwassuspendedin2014.However,allparticipatinglaboratories(ALS,Ultratrace,Genalysis,Becquerel)andAAGagreedthattheaimoftheprogramwassound,andtheprogramhasbeenrevised.Actlabs,ALS-Australia,Intertek-Genaly-sis,andBureauVeritasUltratracehaveagreedtobepartofthisrevisedversionoftheStudentSupportprogram. Initsrevampedform,participatinglaboratoriesdonothavetopre-commitfundstotheprogram,butcanchoosewhethertheywilloffersupport–andtowhatlevel–onacase-by-casebasis.Thisrevisionmeansthatlaboratoriesarenotobligedtosupportallprojectsofferedtothem,butalsothatprojectsendorsedbyAAG’sEducationCommit-teemaynotreceivesupport,ormayonlyreceivepartialsupport.Thesechangestotheprogramhavenot,however,affectedtheapplicationprocess.ApplicationscanbemadeusingtheformavailableontheStudentspageoftheAAGwebsite(www.appliedgeochemists.org).Followingsubmis-sionofthecompletedformtoAAG’sEducationCommit-tee([email protected]),themeritoftheapplicationisassessed,andthoseworthyofsupportarerecommendedtoparticipatinglaboratories.Inmakingtheapplication,itisusefultolookatthescopeofworkthatisofferedbyparticipatinglaboratoriesassetoutintheirscheduleofservicesavailableontheirrespectivewebsites.Theseschedulesalsoprovideanalyticalcosts:inmakingthe

application,itismorelikelythatanapplicationwillreceivesupportfromAAG’sEducationCommitteeandcommit-mentfromlaboratoriesifthescopeofworkrequestedisstronglyalignedwithappliedgeochemistryandrealisticintermsofcosts. ExamplesofgeochemicalresearchsupportedbyAAG’sStudentSupportProgramincludeprojectscarriedoutbyAndyLucasandXinDu,bothofwhomreceivedin-kindanalyticalsupportfromIntertek-Genalysis.BothAndyandXinfulfilledtheirobligationsfromtheAAGStudentSup-portProgrambypublishinginEXPLORE: Lucas,A.R.,Rate,A.W.,Salmon,S.U.,Reid,N.,Anand,R.R.,2013.Evaluatingthediffusivegradientsinthinfilmstechniqueforthedetectionofmulti-elementanomaliesinsoils.EXPLORE,161,1-15. Du,X.,Rate,A.W.,Gee,M.A.M.,2012.ParticlesizefractionationandchemicalspeciationofREEinalateriticweatheringprofileinWesternAustralia.EXPLORE,157,1-14. Currently,studentsMarcusPhua(UniversityofMel-bourne)andEnerstTata(UniversityofBuea,Cameroon)havereceivedsupportfortheirresearch.Marcus’sworkinvolvesthepetrogenesisofgabbroicintrusionshostingNi–Cu–PGEmineralizationinWesternTasmania(supportedbyBureauVeritas–Ultratrace),andEnerst’sPhDthesisdealswithgranite-hostedgoldmineralizationfromsouth-eastCameroon(supportedbyIntertek-Genalysis). IftheAAGStudentSupportProgramisofinteresttoyouasasupervisor,orasastudentofappliedgeochemistry,pleasevisittheStudentpageoftheAAGwebsite(https://www.appliedgeochemists.org)tofindoutmoreaboutthisprogram,anddownloadanapplicationform.

Paul MorrisChair, AAG Education Committee

ThisextensivelyupdatedneweditionofthewidelyacclaimedTreatiseonGeochemistryhasincreaseditscoveragebeyondthewiderangeofgeochemicalsubjectareasinthefirstedition,withfivenewvolumeswhichinclude:thehistoryoftheatmosphere,geochemistryofmineraldeposits,archaeologyandanthropology,organicgeochem-istryandanalyticalgeochemistry.Inaddition,theoriginalVolume1on"Meteorites,Comets,andPlanets"wasexpandedintotwoseparatevolumesdealingwithmeteoritesandplanets,respectively.TheseadditionsincreasedthenumberofvolumesintheTreatisefrom9to15withtheindex/appendicesvolumeremainingasthelastvolume(Volume16).Eachoftheoriginalvolumeswasscrutinizedbytheap-propriatevolumeeditors,withrespecttonecessaryrevisionsaswellasadditionsanddeletions.Asaresult,27%wererepublishedwithoutmajorchanges,66%wererevisedand126newchapterswereadded. Formoreinformationpleasegotoon:http://www.researchandmarkets.com/publication/me5b86z/treatise_on_geochemistry


Student-Industry mineral exploration workshop

Inanefforttoattractmorestudentsintothemineralexplorationindustry,theProspectorsandDevelopersAsso-ciationofCanada(PDAC)convenedits9thannualStudent-IndustryMineralExplorationWorkshop(S-IMEW)fromMay1-15,2015.Twenty-sixseniorgeosciencestudentsfromuniversitiesandcollegesfromacrossCanadaconvergedonSudburytoparticipateinlectures,presentationsandhands-onsessionscoveringexplorationtechniques,mineraldeposits,geophysics,geochemistry,environmental,healthandsafetyandcorporatesocialresponsibilityissues.Thetwo-week,allexpenses-paidgatheringprovidedthestudentswithanopportunitytoexperiencethemanyfacetsofthemineralexplorationindustry. ‘GeochemistryDay’isoneofthehighlightsoftheworkshopeachyearandwasorganizedandtaughtthisyearbyStewHamilton,RichardDyer,AndyBajc,andSarahHashmioftheOntarioGeologicalSurveyandBethMc-ClenaghanfromtheGeologicalSurveyofCanada.Theyintroducedstudentstoexplorationgeochemicaltechniquesandprovidedhands-onfieldandlabexperiencesthatstudentswereunlikelytoreceiveatuniversity,includingor-ganiclakesedimentsampling,soilprofilesandtillsampling,andthemicroscopicworldofindicatorminerals. Theworkshopwasagreatopportunityforstudentstolearnaboutthewidevarietyofcareeropportunitiesinmineralexploration,gainexperiencewithexplorationtech-niquesnottypicallytaughttoundergraduatestudentsandexperiencesomeoftheadventuresofbeingageoscientist. InformationaboutthePDAC’sS-IMEWprogramisavailableatthisweblink:http://www.pdac.ca/programs/students/s-imew/

Beth McClenaghanGeological Survey of Canada

Voting Members

DavidMurphyAnglogoldAshantiLtd.PrincipalGeochemist19WhitfieldSt.Floreat,WAAUSTRALIA6014Membershipno.3675 PerttiSaralaGeologicalSurveyofFinlandP.O.Box77Rovaniemi,FINLAND96101Membershipno.3893

Regular Members StephenDeWitConsultingGeologist3020MeadowDriveNanaimo,B.C.CANADAV9R7C6Membership#4307 SusanDriebergPrincipalGeochemist,RioTinto224N2200WestSaltLakeCity,UTUSA84116Membership#4308 EvgeniaLebedevaGeochemist,Intertek156CanningHighwaySouthPerth,WAAUSTRALIA6151Membership#4310 DouglasC.MenziesConsultingGeologist,Geoinsite16CullenDriveKiama,NSWAUSTRALIA2533Membership#4311 Student Members JasmineA.MoertleCaliforniaStateUniversity,LongBeach6750E.RosebaySt.LongBeach,CAUSA90808Membership#4309

New AAG Members

Students examining indicator minerals during Geochem-istry Day lab exercise.


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CALENDAR OF EVENTSInternational,national,andregionalmeetingsofinteresttocolleaguesworkinginexploration,environmentalandotherareasofappliedgeochemistry.TheseeventsalsoappearontheAAGwebpageat:www.appliedgeochemists.org.

Pleaseletusknowofyoureventsbysendingdetailsto:Steve Amor

GeologicalSurveyofNewfoundlandandLabradorP.O.Box8700,St.John’s,NL,Canada,A1B4J6

Email:[email protected]:+1-709-729-1161

2016 10-16JANUARY WinterConferenceonPlasma Spectrochemistry.TucsonAZUSA. Website:icpinformation.org/ Winter_Conference.html19-21JANUARY 10thInternationalSymposiumon EnvironmentalGeochemistry.PerthAustralia. Website:www.iseg10.com/25-28JANUARY MineralExplorationRoundup.Vancouver BCCanada.Website:amebc.ca/roundup5-6FEBRUARY AtlanticGeoscienceSocietyAnnual Colloquium.TruroNSCanada.Website: www.acadiau.ca/~raeside/ags2016/14-18FEBRUARY TheMineralsMetals&MaterialsSociety 145thAnnualMeeting&Exhibition.Nash- villeTNUSA. Website:tinyurl.com/nbdyqeh21-26FEBRUARY2016OceanSciencesMeeting.NewOrleans LAUSA.Website:osm.agu.org/2016/6-9MARCH ProspectorsandDevelopersAssociationof CanadaAnnualConvention.TorontoON Canada.Website:www.pdac.ca/convention21-23MARCH NorthAtlanticCratonMeetingEdinburgh UK.Website:www.bgs.ac.uk/nac201617-22APRIL EuropeanGeosciencesUnionGeneral Assembly2016.ViennaAustria.Website: www.egu2016.eu/16-18MAY 7thGeochemistrySymposiumwithInter- nationalParticipation.SideTurkey. Website:jeokimya.ankara.edu.tr/en22-25MAY 10thSouthAmericanSymposiumon IsotopeGeology.PuertoVallartaMexico. Website:www.ssagi10.geofisica.unam.mx/1-3JUNE GAC/MACAnnualMeeting.Whitehorse YTCanada.Website:whitehorse2016.ca/13-17JUNE 8thInternationalSiberianEarlyCareer GeoScientistsConference.Novosibirsk Russia.Website:conf.ict.nsc.ru/sibconf201619-23JUNE 6thInternationalCongressonArsenic intheEnvironment.StockholmSweden. Website:www.as2016.se26-30JUNE AustralianEarthSciencesConvention. AdelaideSAAustralia.Website: aesc2016.gsa.org.au26JUNE-1JULYGoldschmidt2016.YokohamaJapan. Website:www.geochemsoc.org/programs/ goldschmidtconference/10-13JULY 3rdInternationalConferenceon3D MaterialsScience.St.CharlesILUSA. Website:tinyurl.com/psr55at

10-13JULY 9thInternationalConferenceonEnviron- mentalCatalysis.NewcastleAustralia. Website:tinyurl.com/pts5mtv11-15JULY 4thInternationalWorkshoponHighly SiderophileElementGeochemistry. DurhamUK. Website:community.dur.ac.uk/hse.ws17-22JULY Eurosoil2016.IstanbulTurkey.Website: www.eurosoil2016istanbul.org19-21JULY 39thInternationalSymposiumonEnviron- mentalAnalyticalChemistry.Hamburg GermanyWebsite:tinyurl.com/pnaswjw23-27JULY EuroscienceOpenForum2016.Manchester UK.Website:www.esof.eu24-28JULY Microscopy&Microanalysis2016. ColumbusOHUSA. Website:tinyurl.com/pdyxkpz27-28JULY 8thInternationalCongressofEnvironmen- talResearch.LübeckGermany.Website: www.icer16.jerad.org20-21AUGUST 6thInternationalConferenceonEnviron- mentalPollutionandRemediation. BudapestHungary.Website:icepr.org21-25AUGUST 33rdInternationalGeographicalCongress. BeijingChinaWebsite:www.igc2016.org27AUGUST– 35thInternationalGeologicalCongress4SEPTEMBER CapeTownSouthAfrica. Website:www.35igc.org4-7SEPTEMBER IAP2016:InterfacesAgainstPollution. LleidaSpain.Website:www.iap2016.org4-7SEPTEMBER15thWorkshoponProgressinTraceMetal SpeciationforEnvironmentalAnalytical Chemistry.GdanskPoland.Website:chem. pg.edu.pl/tracespec5-9SEPTEMBER 13thInternationalNickel-Copper-PGE Symposium.FremantleWAAustralia. Website:www.iagod.org/node/5811-15SEPTEMBER2ndEuropeanMineralogicalConference. RiminiItaly. Website:emc2016.socminpet.it/25-28SEPTEMBERSEG2016Conference:TethyanTectonics andMetallogeny.ÇeşmeTurkey.Website: www.seg2016.org9-13OCTOBER WorldWaterCongress&Exhibition. BrisbaneQLDAustralia. Website:tinyurl.com/pgrbkwu16-21OCTOBER WaterRockInteraction15.ÉvoraPortugal. Website(pdf):tinyurl.com/lch75x8


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TEL: (613) 828-0199 FAX: (613) 828-9288, e-mail: [email protected]

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Ryan Noble, Vice-President CSIRO P.O. Box 1130 Bentley, Australia 6102 TEL: +61 8 6436 8684 email: [email protected]

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AAG COORDINATORS

AAG Student Paper PrizeDavid Cohen, [email protected]

AAG WebsiteGemma Bonham-Carter, [email protected] Coordinator: Bruno Lemiere, [email protected]

Geoscience CouncilsDavid Cohen, [email protected]

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EXPLOREBeth McClenaghan, [email protected]

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AAG Regional CouncillorsRyan Noble, [email protected]

2015-2016 Dave Cohen Ray Lett Tom Molyneux Juan Carlos Ordóñez Calderón Peter Rogers Peter Winterburn

OFFICERSJanuary - December 2015

Documents

NUMBER 169 DECEMBER 2015-Version 2 Gold Homogeneity in ... Number... · The December 2015 issue of EXPLORE features a technical article about gold homogeneity in certified reference