Archaeological Chemistry

454 Pages·2008·11.14 MB·English

by  Mark A. Pollard

Archaeological Chemistry
Second Edition

Archaeological Chemistry
Second Edition
A. Mark Pollard
Research Laboratory for Archaeology and the History of Art, University of
Oxford, Oxford, UK
Carl Heron
Department of Archaeological Sciences, University of Bradford, Bradford, UK
ISBN:978-0-85404-262-3
AcataloguerecordforthisbookisavailablefromtheBritishLibrary
rTheRoyalSocietyofChemistry2008
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Foreword to the First Edition
Archaeological scienceisadisciplinewhichisgrowingrapidlyinitsscopeand
maturity. The application of techniques deriving from the natural sciences to
archaeological research is, of course, not new and the present volume rightly
emphasizes some of the earlier initiatives in the field of archaeological chem-
istry. But amongst the indicators of this increasing maturity are the quality of
the science, on the one hand, and a growing awareness of the problems of
interpretation on the other.
ThisworkbyPollardandHeronperformsavaluableserviceindefiningmore
carefullythanhithertoand thenrichlyexemplifyingthefieldof archaeological
chemistry,and itisfittingthat it should bepublished byThe Royal Societyof
Chemistry.Hithertoitisperhapsthedisciplineofphysicswhichhascomeinfor
a good deal of the limelight since it holds what is almost a monopoly in two
importantfieldsofarchaeologicalscience:datingandprospecting.Someofthe
techniquesofdatingmayindeedbeincludedwithintheprovinceofchemistry:
aminoacidracemizationisdealtwithveryfullyhere,andobsidianhydrationis
mentioned. But many of the most useful dating methods are dependent upon
radioactivity, a subject area often relinquished to physics. And again many of
the techniques of field prospection – resistivity surveys, use of the proton
magnetometer, etc. – fall within the same province.
Asdefinedhereitis,veryreasonably,chemicalanalysiswhichliesattheheart
ofarchaeologicalchemistry.Therefore,followingthehistoricalintroduction,a
wide-ranging survey of analytical techniques is undertaken which certainly
offers the best overview currently available to the archaeologist. This is
followed by what at first sight seems a comprehensive survey of examples
andapplications.Oncloserexamination,however,itemergesthatnearlyevery
chapter is based in good measure upon the original research of one of the
authors, supplemented by a further overview. Thus Heron’s work on organic
residues, notably resins, is put to very good use. Pollard’s researches in the
characterizationofceramics,inglassstudies,andintheuseofbrassandother
metals likewise form the basis for much wider reviews of important fields.
Oneofthegreatstrengthsofthebookinmyviewisitsclearperceptionthat
archaeology and archaeological science, although interrelated and
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vi Foreword to the First Edition
interdependent,arenotatallthesamething.Fortheinterpretationofthedata
of archaeological science is a complicated and difficult matter, and it involves
two separate operations. The first, the elucidation of rather concrete, factual
questions – ‘how old is this sample?’, ‘where did it come from?’, ‘how has it
been modified through burial in the ground?’ – fall within archaeological
science proper. But this does not make them easy questions: the difficulties in
the interpretation of the data from lead isotope analysis obtained in order to
determine the places of origin of metals used in the Aegean is a case in point.
Anothersuchquestionwouldbetheageandauthenticityofthematerialsfrom
the French site of Gloze1 – perhaps wisely not dealt with here, but still an
unresolvedprobleminthefieldofarchaeologicalscience.Thesecondoperation
is to achieve a clearer realization of the implications of such concrete conclu-
sions for the understanding of human behaviour in the past. There the
archaeologists and the archaeological scientists have yet to find more effective
ways of working together: the thoughtful caution in the book makes an
excellent start.
Archaeological chemistry is clearly not the same field as materials science,
although the two overlap, nor as metallurgy: Chapter 6 draws a distinction
between ‘the chemical study of metals’ and (I presume) the application of
metallurgical techniques to elucidate the history of the working of individual
artefacts. And this suggests to me that there lies here another sub-field which
has not yet emerged, fully fledged, in its own right: the archaeology of
technology,orarchaeo-technology.Forthetimewillcomewhenweshallwish
to focus more clearly upon processes and procedures of manufacture. The
concept of the‘chaine operatoire’nowcommonly appliedtothe study oflithic
artefacts and to the sequence of operations undertaken in their manufacture
hasbeenappliedalreadytoceramicsandcancertainlybeappliedalsotoother
productsofpyrotechnology.TextsareavailablefromMesopotamiawhichgive
recipes for various preparation procedures, for instance those of metals, and
veryoddreadingtheymakeformoderneyes.Thissuggeststomethatthestudy
of ancient technology, giving more attention to what the ancient smiths,
potters,glassblowers,anddyersthoughttheyweredoing–thisistosay,laying
greater emphasis upon cognitive aspects – will soon be a possibility. But in
order to do this a prerequisite is to get the modern science right, and that is
what Pollard and Heron are so systematically doing. It is a great pleasure to
introduceaworkwhich,moreclearlythaneverbefore,delineatesanimportant
field within archaeological science and thus makes an important contribution
to the discipline as a whole.
Colin Renfrew
Cambridge
January 1996
Preface to the First Edition
Archaeological chemistry isthe application of chemicalknowledge inorderto
helpsolveproblemsinarchaeology.Itis,however,muchmorethanastraight-
forward application of existing techniques to new and interesting questions.
Many of the chemical questions posed are unique to archaeology, although,
somewhatsurprisingly,manyotherdisciplinesshare,fromtimetotime,similar
concerns. Our premise is that archaeological chemistry requires a thorough
understandingofthebackgroundofbothhalvesofthestory,andoftenmastery
ofinformationfromrelateddisciplinessuchasbiochemistryandgeochemistry.
This book is therefore aimed at two groups – chemists who are interested in
newapplications,andalsoarchaeologists,particularlythoseonundergraduate
and postgraduate courses encompassing aspects of scientific archaeology.
It will also be of interest to geochemists, materials scientists and forensic
scientists.Perhapsthemostimportantmessageitcontainsistheneedtotackle
fundamental issues of chemical change in archaeological materials if scientific
analysis is to make major contributions to the study of the past.
Thecontinuedexpansionofscientificapplicationsinthestudyofthepastis
onereasonforwritingthisbook.Ifthetitleofthebookisnotentirelynew,then
we believe our approach is – the adoption of a thematic structure. There are
severalreasonsforthis.Firstly,themajorityofprevioustextsinarchaeological
science have tended to emphasize techniques at the expense of applications.
Nowadays, there are so many techniques that such an approach would be
unduly laborious, although some of the more important techniques are
summarized in Chapter 2. Secondly, through an examination of particular
themes,itispossibletodocumentthesuccessesandfailuresofpastapplications
andassesstheimpactofscientificanalysisonspecificarchaeologicalproblems.
Itisalsopossibletoseecontemporarydebatesintermsofcompetingscientific
views and to suggest how these might be resolved from a knowledge of the
underlying principles. In Chapter 1, we provide a short historical context and
return to general issues and future challenges in the final chapter.
ArchaeologicalChemistry,SecondEdition
ByA.MarkPollardandCarlHeron
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viii Preface to the First Edition
We are aware of a Eurocentric bias in most of the chapters, although the
issues raised will be applicable to other contexts. The majority of chapters
featuretheresultsofprimaryresearchcarriedoutseparatelybytheauthorsin
collaboration with other colleagues. It is not possible to do justice to every
applicationofchemistrytoarchaeologyinasinglevolume;someofthecriteria
forinclusionarediscussedaboveandinChapter1.Assuch,thisbookdoesnot
pretend to be a truly balanced review of archaeological chemistry and some
readers may feel that some heinous crime of omission has been committed.
We hope, however, that there is enough of interest to justify the attempt to
adopt a unified approach to archaeological chemistry as a worthwhile area of
endeavour in its own right.
Mark Pollard and Carl Heron
Bradford, December 1995
Preface to Second Edition
Muchhashappenedintheworldofarchaeologicalchemistrysincewesatdown
towritethePrefacetotheFirstEditionofthisvolumeinDecember1995.New
centres of research have emerged, whilst some established centres, sadly, have
closeddownasseniorfiguresretireorequipmentisphasedout.Analyticaland
interpretativetechniqueshavedevelopedimmeasurably–comparethedescrip-
tion of optical emission spectroscopy with that of laser-ablation inductively
coupled plasma mass spectrometry. Although we might miss (in a masochistic
sort of way!) the care and attention necessary to ensure that the graphite
electrode was just the right distance above the cup, and that the photographic
plate was developed for just the right length of time, there is no doubting the
improvements made in analytical sensitivity, reproducibility and sample
throughput.
We referred in the first edition to the ‘golden age of archaeometry’, being
that period inthe1960s and1970s, when, forsome archaeologists atleast, the
chemical analysis of inorganic materials was an essential component of the
investigationofprehistoriccontactandexchange.Curiously,eventhoughsuch
analysishasbecomegenerallyeasier,better,cheaperandmoreavailable,there
has been a perceptible decline of interest in such studies. This is perhaps a
consequence of the debate about the use of lead isotope data in the Aegean
duringthe1990s.Archaeologistshavebeenleftunsureabouthowtousethese
data, given the various competing interpretations presented from, apparently,
thesamedata.They mayalsobe slightlybemused bythewholespectacle, and
certainly not prepared to invest any more time in the venture until greater
consensus is achieved. Given the fact that, with new instrumentation, such
measurements are easier and faster to make than ever before, this is clearly
regrettable, and we certainly encourage a new generation of archaeological
chemists to return to this and other related issues. We hope this volume will
provide the stimulus for some to do so.
ArchaeologicalChemistry,SecondEdition
ByA.MarkPollardandCarlHeron
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