Rhe CA]IADIA]I Mtileratoglsil JOUR]IIAIOF the MINERALOGICAT ASSOCIATIOIII OFGANADA
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253 BUttETIItIDE I..ASSOCIATIOfII MINERATOGIOUE DUCATIIADA rHE CA]IADIA]I MTilERATOGlsil JOUR]IIAIOF THE MINERALOGICAT ASSOCIATIOIII OFGANADA Volume31 June1993 Part2 Canadinn Mineralogist Vol. 31, pp. 253-296 (1993) MINEHALS,MINERALOGV AND MINERALOGISTS: PAST,PRESENT AND FUTURE- FRANKC. HAWTHORNE Depantnentof GeologicalSciences, University of Manitoba, Winnipeg,Manitoba R3T2N2 ABSTRACT Minerals are the basicmaterials of the Earth, andvirtually everythingone doesin the Earth SciencesinvolveB minerals in one way or another,Minerals fumish a good part of the wealththat is the basisof our society,not just ascommercial products but as the soils that support our agriculture and the aquifers that hold our water supplies.Minerals have played a key role in the developmentof humanity.One of our first scientific actswas to distinguishbetween different mcks and minerals,and usethem as tools accordingto their properties.With the widespreaddevelopment of mining and trade,it becameimportant for peopleto recognizeminerals, and writings on mineral recognitionand propertieswere commonin many societies:China Greece,Rome, Persia.Arabia Italy, Germany. Extensivechemical work on mineralsbegan in the late 18thcentury, resulting in the developmentby Berzeliusofthe "anionic" classificationof minerals.The developmentof crystal-structure analysis hadamajoreffectonMineralogy;the workof W.L. Bragg gavean atomistic basis forourknowledgeof mineralchemistry andproperties, andthe workof V.M. Goldschmidtgave atheoretical 6asisfor thebehavior of elementsin geochemicalprocesses. The last 30 yearshas seen a flood of new techniquesinto Mineralogy: electron-microprobeanalysis and crystal-structurerefinement were followed by numerousspectroscopic techniques, many new microprobemethods for both elementaland isotopic analysis,and both scanningand transmissionelectron microscopy.The immenseamount of datastimulated the developmentof TheoreticalMineralogy. Atom ("ionic") andelectron('tovalent") models are now capableof accuratelycalculating stereochemical details and a wide array of physical and dynamicproperties. The first stepsto understandthe thermodynamicbasis of elementordering, elementexchange and mineral reactionshave now led to geothermobarometerscapable of determining equilibration conditions to l25oC and 11 kbar. Recent initiatives in surface mineralogyhave been encouraged by the importanceof surfaceproperties of mineralsin environmentalproblems. Mineralogy permeatesevery facet of Earth Sciences,and reachesout to many contiguousareas in Physics,Chemistry and Materials Science.Unforrunately, this great diversity has adverselyaffected the generalview ofMineralogy within the Earth Sciences:many Earth Scientistsare not conve$antwith the breadthand intellectual vitality of currentwork in Mineralogy.With pressureon University budgets,both from decreasingGovernment support and from the developmentof importantnew areas(e.8. ' EnvironmentalScienies), there is a dangerthatMineralogy will bediscarded as a specificcore discipline ofEarth Scienceresearch andteaching. If Mineralogy is taughthaphazardly as pa4s of the othersubdisciplines in Earth Sciences,students will not develop a feel for thl divenity of mineralsand their behaviorin the wide variety of tenestrial environments.The end result will be a generationof Earth Scientistswho lack fundamentalundentanding of the materialswith which they work, and who will be incapableof adaptingto new areasof expansionwithin andperipheral to Earth Sciences.It is up to Mineralogiststo preventthis from happening. Keyword Mineralogy. ' Presidentialaddress delivered at Wolfville, Nova Scotiaon May 26th,1992. 254 THE CANADIAN MINERALOGIST SOMMAIRE Les min6rauxconstituent les mat6riauxde basede la terre; d'une fagon ou d'une autre,les activit6sde tout g6oscienufique gravitentautour des min6raux. Ce sont les min6rauxqui foumissentune partie imporrantede la richessequ'est le fondementde none soci6t6,non seulementsous la guisede produitscommerciaux, mais aussi comme constituents des sols qui supportentnotre agricultureet des couchesaquifbres qui contiennentles ressourcesd'eau souterraine.lrs min6rauxontjou6 un r6le-cl6 dansle ddveloppementde I'humanit6. Un despremiers gestes scientifiques a 6t6la discriminationparmi lesdiffdrentes roches et mindraux, afin demieux choisirles mat6riauxpropices d la fabricationd'outils. Avec le d6veloppementde I'industrie minidreet des&hanges commerciales,il s'est avdrdimportant de reconnaltreles mindraux.Aussi, les &rits sur les caractdristiqueset les propri6t€sdes min6rauxont-ils 6td courann dansplusieurs socidtds, en Chine,en Grdce,en Perse,en Arabie, en Italie et en Allemagne,d titre d'exemples. L'6tude de la chimie desmin6raux a d6butdvers la fin du dix-huitidmesidcle; de telles 6tudesont men6au d6veloppmentde la classification"anionique" desmindraux par Berzelius.Ia possibilitdde d6terminerla structurecristalline desmin6raux a eu un effet majeur sur la Min6ralogie.Les travauxde W.L. Bragg ont donndune baseatomiste i nos connaissancesde la composition chimique et des propri6t6sdes rnin6raux.Les travaux de V.M. Goldschmidtont foumi la baseth6orique du comportementdes 6l6mentsdans les processus g6ochimiques.I-a demibre trentaine d'ann&s a vu uneflopp6edetechniques nouvelles enMin6ralogie: la possibilit6d'effectuer des analyses h la microsondedlectronique de mindrauxet d'en affiner la structurecristalline a 6td suivie par de nombreusestechniques spectroscopiques, avec plusieurs m6thodes nouvelles d'analyses par microsondepour ddterminer soit la teneurdes 6l6ments ou les rapportsisotopiques, et la microscopiedlectronique i balayageet par transmission.La quantit6 immensede donn6esnouvelles a stimul6 le d6veloppementde la Mindralogiethdorique. Des modblesatoniques ('toniques") et 6lectroniques('tovalents") sont maintenantcapables de calculerles ddtailsst6r6ochimiques et un 6ventailimposant de propridt6s physiqueset dynamiques.Les premibres6bauches d'une comprdhensionde la basethermodynamique de la mise en ordre des 6l6ments,de leur 6change,et des rdactionsparmi ces mindrauxont permis de formuler des g6othermobaromdtrescapables de ddterminerles conditions d'6quilibre A25'C et i I kilobar prbs.Des initiatives r6centes dans l'6tude dessurfaces ont 6tdentreprises i causede la grandeimportance des propri6t6s des surfaces dans les problbmesde l'environnement. l,a Min6ralogieinfluence profond6ment chaque aspect des sciences de la terre,et elle 6tablit desliens avec les domainescontigus en physique,chimie, et sciencedes matdriaux.Malheureusement, cette grande divenit6 a exerc6un effet n6gatif dansl'opinion qu'ont plusieun i propos du rdle de la Mn6ralogie dansles sciencesde la terre. Plusieursg6oscientifiques ne sont pas bien renseigndsi propos de I'envergureet de la vitalit6 intellectuelledes travaux courantsen Min6ralogie.Avec les compressions budg6tairesdans nos universitds,d caused'une diminurion dansles octrois gouvenementauxet du ddveloppementde domaines nouveaux,comme par exempleles sciencesde l'environnement,je pergoisun dangerque la Min6ralogiesera ray6e de la liste des disciplinesessentielles dans l'enseignement et la rechercheen sciencesde la terre.Si on enseignela mindralogiede fagonal6atoile commepartie d'autressous-disciplines dans les sciencesde la terre, commentles dtudiantspourront-ils apprendre i proposde la diversit6des mindraux et leur comportementdans une varidt6 de milieux terrestres?11 en rdsulterai! 6ventuellement,une g€neration deg6oscientifiques qui nepossddentpasune maltrise des matfriaux qu'ils 6tudient,etqui sontincapablesde s'adapteraux nouvelles disciplinesau sein des sciencesde la tene et dansles domainespluridisciplinaires connexes. Il incombeaux min6ralogistesde faire les ddmarchesn6cessaires porr contr€rcette 6volution n6faste. Clraduit par la Rddaction) M ots- c 16: Mindralogie. Ir\'rRoDUc"noN TITE CENTR,AL RoLEoF MINERALOGY INTI{E EARTTTSCTENCES Many yearsago, I was an undergraduatein Geology attheRoyal School ofMines in London.Irememberthaf The centralrole of Mineralogy in the Earth Sciences minerals and their recognition were emphasizedfrom is illustratedschematically in Figure 1. There are many the start of the undergraduateprograrl and this contin- more branchesof the Earth Sciencesthat could be ued throughto the end.The messagewas simple: r/yoa included(e.9., geochemistry, paleontology, geochronol- can't recognizeminerals, you won'tfind mines!Miner- ogy), and toward the end of this article, I will mention alogy was emphasizedas one of the core disciplinesof the role of Mneralogy in some of the less traditional Geology, what today is more fashionableto call Geo- areasof the Earth Sciences(e.9., EnvironmentalSci- logical Sciences.It hasalways been surprising to methat ences,Atmospheric Sciences). However, the subsetof Mineralogy receivesmuch less attention in the Earth topics in Figure I is sufficient to make the point that Sciencescurriculaof North America.asrninerals are the virtually everyttring one does in the Earttr Sciences basic materialsof the Eanh (andplanets), and furnish a involves mineralsin one way or another. goodproportion ofthe wealththat supportsour society. In Petrology,be it igneous,sedimentary or metamor- MINERAIJ. MINERALOGY AND MINERALOGISTS 255 exploitation,but againMineralogy has its partto play in designingoptimum processesof ore beneficiationand extraction. tn Geophysics,one is concernedwith the physicalproperties ofminerals. The elasticproperties of minerals are of interest to the seismologist,and the magnetic properties of minerals are of interest