Infrare D Transmission Spectra of Carbonate Minerals

Infrare d Transmission Spectra of Carbonate Mineral s THE NATURAL HISTORY MUSEUM Infrare d Transmission Spectra of Carbonate Mineral s G. C. Jones Department of Mineralogy The Natural History Museum London, UK and B. Jackson Department of Geology Royal Museum of Scotland Edinburgh, UK A collaborative project of The Natural History Museum and National Museums of Scotland E3 SPRINGER-SCIENCE+BUSINESS MEDIA, B.V. Firs t editio n 1 993 © 1993 Springer Science+Business Media Dordrecht Originally published by Chapman & Hall in 1993 Softcover reprint of the hardcover 1st edition 1993 Typese t at the Natura l Histor y Museu m ISBN 978-94-010-4940-5 ISBN 978-94-011-2120-0 (eBook) DOI 10.1007/978-94-011-2120-0 Apar t fro m any fair dealin g for the purpose s of researc h or privat e study , or criticis m or review , as permitte d unde r the UK Copyrigh t Design s and Patent s Act , 1988, thi s publicatio n may not be reproduced , stored , or transmitted , in any for m or by any means , withou t the prio r permissio n in writin g of the publishers , or in the case of reprographi c reproductio n onl y in accordanc e wit h the term s of the licence s issue d by the Copyrigh t Licensin g Agenc y in the UK, or in accordanc e wit h the term s of licence s issue d by the appropriat e Reproductio n Right s Organizatio n outsid e the UK. Enquirie s concernin g reproductio n outsid e the term s state d here shoul d be sent to the publisher s at the Londo n addres s printe d on thi s page. The publishe r makes no representation , expres s or implied , wit h regar d to the accurac y of the informatio n containe d in thi s boo k and canno t accep t any legal responsibilit y or liabilit y for any error s or omission s that may be made. A catalogu e recor d for thi s boo k is availabl e fro m the Britis h Librar y Librar y of Congres s Cataloging-in-Publicatio n Data availabl e (oö) Printed on acid-free text paper, manufactured in accordance with ANSI/NISO Z39.48-1992(Permanence of Paper) Contents Foreword vii Introduction viii A guide to the book IX The mineral specimens ix Instrumentationand samplepreparation ix The spectra ix The text pages x Generalreferences xi Index of spectraby mineral name xii Index of spectraby chemicalclass xiii The spectra 1 Foreword The selectedspectra presented in this volume are a testimonyto the diversity of mineralcarbonates. Their compositional variety embracesmany of the chemical elements and is increasedby the frequentpresence of solid solution betweenmembers. They occurin all the broadcategories of rock types: igneous, metamorphic,metasomatic and sedimentary;and they are often associatedwith important ores and rare elementdeposits. Carbonates are not only of significancein the geological domain, but also in industry and materials science. Accurate identification of the compoundsis, therefore,vital for a proper understandingof any carbonatebearing system. The developmentof Fourier transforminfrared spectrometryhas beenfor someyears at the stage where the acquisitionof spectrais relatively simple, rapid and with good resolution. For identification, the method is inexpensive and can provide additional information on the nature of the chemicalbonding. It is particularly suited to carbonatesbecause of its ability to discriminateclearly betweenthe different members. It is obvious that to be able to produce a large set of definitive spectra, a source of well- characterizedminerals is required, but the location of such a sourceis not necessarilyso obvious. Our two museums- The Natural History Museum in London and the National Museums of Scotlandin Edinburgh- have joined forces to provide such a source,using their renownedmineral collectionsand authenticatingeach mineral by modernadvanced methods of analysisand identification. This volume is the product of severalyears' work of high quality. We believe that it gives for today the most readily available compilation of reliable IR spectraas an invaluablereference tool for many. ProfessorPaul Henderson Keeperof Mineralogy The Natural History Museum, London and Dr Ian Rolfe Keeperof Geology National Museumsof Scotland,Edinburgh May, 1993 Introduction The purposeof this compilation is to make available recently-acquiredspectra of as many well- characterizedcarbonate minerals as possiblein order to further the use of infrared spectroscopyin mineralogy. With the recentincreased availability of Fourier transformspectrometers for routine laboratory use, there is great potential for infrared spectroscopyto becomemore widely used, both for the rapid identification of minerals and for more detailed structural studies. Despite being an estab- lished analytical technique,mineralogical infrared spectroscopyhas beenhandicapped by a lack of high-quality referencespectra. There is currently no infrared equivalent of the JCPDS Mineral Powder Diffraction File and many new mineral descriptionsstill lack infrared spectra. Several compilationsof mineral spectraare available but are far from comprehensiveand are of variable reliability. Publishedmineral spectraare scatteredthroughout numerousjournals and are often poorly reproducedwith limited frequencyranges. The successof any comparativetechnique depends to a greatextent on the availability and quality of referencestandards. A spectrumis a virtually unique "fingerprint" of a material and, accurately reproduced,is a much more useful aid to identification than tabulatedabsorptions alone, from which all subtletiesof detail are lost. The more spectrathat are published,the more widely usedthe techniquebecomes and so the cycle continues. The authors acknowledgethe co-operationand advice of their colleagues,particularly John Francisand PeterDavidson for x-ray diffraction work, and the mineral curatorsfor their tolerance of our frequent requestsfor material from their best specimens. A guide to the book The mineral specimens The majority of the mineral specimensused in this compilation are from the collections of the Mineralogy Department of The Natural History Museum, London, and the Department of Geology, Royal Museum of Scotland, Edinburgh. Others were acquired from dealers and col- leaguesspecifically for this work. The criteria usedin selectingspecimens were as follows: • purity and homogeneity; • specimenspreviously usedas x-ray powder diffraction standardswhere possible; • easeof contamination-free,unambiguous sampling; • specimensfrom type or classiclocalities. The rarity of somespecies has madeit necessaryto compromisethese criteria in a small number of cases.In some casesa relatively common mineral has been omitted from this collection, e.g. natron, thermonatrite,stichtite/barbertonite etc. because,despite sampling many specimensfrom various localities, no pure or unambiguousmaterial could be separated. Instrumentation and sample preparation All spectrawere recordedin transmissionmode, using a Fourier transforminfrared spectrophoto- meter(Philips PU9800)and potassiumbromide pressed disks. The instrumentwas purgedwith dry, COz-free air and a blank KBr disk was used to generatethe backgroundwhich is automatically subtractedduring transformation.50 scanswere acquiredusing a DTGS detectorat a resolutionof 2 cm-1 followed by two-passselective smoothing. Sampleswere not weighed, but the quantity used was adjusted to give the strongestpeak maximum at approximately20% T or less, without loss of detail aroundthis peak, subject to the availability of material. Most sampleswere used without prior drying so as to avoid the risk of thermal alteration. Some powdery or poorly-crystalline minerals have significant amounts of adsorbedwater which was reducedby allowing the presseddisk to remainin the dry environmentof the samplechamber for severalhours. This techniquewas not usedfor hydratedminerals, some of which can dehydratevery easily to other phases. The spectra All spectrawere recordedover the frequencyrange 4400-225cm-I, but as none of the minerals studiedhad absorptionpeaks in the range4400-4000 cm-I, the spectraare reproducedhere from 4000 to 225 cm-1 to make best use of the available format. The spectraalso have their vertical expansionadjusted for the samereason. Where multiple sharppeaks are poorly reproducedin the standardformat, an expandedwavenumber plot has beenincluded. The text pages Name: The mineral namein bold type correspondsto that in Hey's Mineral Index (Clark (1993». Formula, crystal systemand spacegroup: Thesedata are takenfrom the referencesources listed at the end of this introductionor from later publishedwork where available. Mineral group: The "mineral group" is that given by The Mineral Database(1989) but with alternativegroupings shown where thesedraw attentionto relationshipsbetween spectra. Chemicalclass, chemicaltype: Theseare taken from Ferraiolo (1982). Specimen: The BM and RMS numberscorrespond to registeredmuseum specimens. The descriptioncorresponds to that on the specimenregistration slip (where available),modified as necessaryto reflect sampling. Source: This is the locality as recordedon the specimenregistration slip, exceptthat some place names have beenchanged to currentusage. Type localities are noted where appropriate. Spectrumref. no: This is a unique identifier for the spectrum(there may be more than one spectrumper mineral name). Samplemedium: This will usually be KBr disk but othertechniques may be usedwhere demanded by the natureof the sample. XRD: A number,if given, indicatesthat the specimenhas beenexamined by x-ray powderdiffraction. The suffix (std) indicatesthe specimenis one that has beenused

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