Ion beam analysis techniques: a powerful set ge tools for identification and sourcing of ancient gems

ION BEAM ANALYSIS TECHNIQUES: A POWERFUL SET GE TOOLS FOR THE IDENTIFICATION AND SOURCING OF ANCIENT GEMS T. C(i¡li{*a o'". J.C. D an'". J.P. Poi o " anci G. Que é INTRODUCTION Gems ones a e de ined as a e mine als ha ing a high cla i y, a high ha dness and showing a b igh colou and a nice shining. The mos impo an gems a e diamond, sapphi e and eme ald. These gems a e callad p ecious s ones. Gems ha e ascina ed man since he ea lies imes. They ha e always been sough ou by man o hei aes he ic and symbolic alué. Due o hei sca ceness and high '^alue, gems we e app ecia ed by he migh y ones as a sign o hei powe (empe o s ^nd kings, digni a ies o eligions ...). Thei high ha dness and henee s ong esismnce o de e io a ion symbolised he e e las ingness o hei eign. This las p ope y is in- e es ing om an a chaeological poin o iew: gems ones a el h ough ime wi hou no iceable al e a ion, e en bu ied in agg essi e en i onmen . On he o he hand, gems oiay be used se e al imes on di e en jewels, possibly cu and polished again. Like spices and o he p ecious and sough -a e i ems, gems we e b ough back om long dis ance. Acco dingly, hey a e good ace s o ancien ading ou es and in luence o ci ilisa ions. Each ci ilisa ion had i s own a ou i e gems ones: lapis lazuli in Egyp ; ambe and eme ald in he Román Empi e; game in ea ly Middle Ages wes em ci il isa ions; jade, uby and sapphi e in Fa -Eas cul u es. Mo eo e , he p o enance o some ancien gems such as eme alds o game s is s ill deba ed. Fo all hese easons, he s udy o gems kep in museum collec ions is a p omising esea ch í eld. 2. ANALYSIS OF GEMSTONES Usually, he iden i ica ion o gems elies on he measu emen o op ical and me- chanical p ope ies: e ac i e index n, bi e ingence, isible op ical spec um, speci ic g a i y p [1]- When gems ones a e se on a jewel, hese measu emen s a e no always Cen e de Reche che e de Res au a ion des Musées de F ance. Palais du Lou e. Pa ís CNRS UMR-171 . 198 T. Cmjmíako. J.-C. Dhw. J.-P. Po/koi > CJ. eadily ca ied ou . Dismoun ing hem om he se ing o sampling is o cou se p o- hibi ed. The p o enance o gems, ha means he geog aphical loca ion o he deposi , is o en in e ed by iden i ying speci ic inclusions. Ano hc possibili y is he chemical cha ac e isa ion o gems ones. In his case, gems a e di ccily idcn i ied by means o hei majo chemical cons i uen s. Fo ins ance, diamond is a pu c ca bón c ys al; niby is an AI2O3 c ys al colou ed by less han 1% C ; sapphi e is also an ALO* c ys al bu i s blue colou is due o ace amoun o Ti and Fe; eme aid is a bc yl o o mula Be3Al2(Si03)6 colou ed by a small amoun o C . The ace clcmen con cn o gems also ca ies aluable in o ma ion. Indeed, some o hese ace elemen s come om he su ounding ocks, being inco po a ed du ing he génesis o he c ys al. Being linked o he geological con ex ( ype o e ain and ock- o ming his o y) ace elemen con- en may ac as a inge p in o he occu cnce o a gems one. A wide ange o ech- niques ha e been applied in iew o pe o m chemical analysis: EMPA. XRF, NAA, ICP/MS, SIMS. Table I summa ises some ea u es o he.se analy ical echniques. O cou se, ca e ul obse a ion o he gems and hei in e nal ea u es using con en ional gemmological means has o be pe o med p io o p oceeding o hese chemical analy sis. Mo eo e , se e al analy ical echniques ha e o en o be combined o in e ing unambiguously he p o enance o a gem. Table 1. Fea u es o se e al analy ical echniques used o he chemical cha ac e isa ion o gems EMPA EDXRF NAA LA-ICP/MS SIMS IBA Elemen ange > Na > Na Selec ed all all all LOD >1.000 ppm 1-1.000 ppm < 1 ppm < 1 ppm < 1 ppm 1-1.000 ppm P obé size pm mm whole sample 10-//m //m 10-// m Des uc i e no no ac i a ion P- des uc i e P- des uc i e no P epa a ion yes / coa ing no no no yes / coa ing no Iso opic in o no no no possible yes no Sample size cm any cm any cm any EMPA: elec ón mic op obe analysis. EDXRF: ene gy-dispe si e X- ay luo esccnce. NAA: neu ón ac i a ion analysis. LA-ICP/MS: lase -ahla ion lon-coupled-pla.sma mass spec ome y. SIMS: seconda y ion ma.is spec ome y. IBA: ion beam analysis. 3. IBA TECHNIQUES: PIXE AND PIGE APPLIED TO THE STUDY OF GEMS I is no he place he e o gi e a comple e desc ip ion o Ion Beam Analysis (IBA) echniques; nume ous books and e iew pape s will ul il his equi emen [2 and 3]. Le us jus ecall ha IBA echniques ely on he same p ocess: iden i ica ion o ele- Til 199 CoNcRi.so Naciiiwi OI AKQi i-(nnn"RlA den al cons i uen s by de ec ing p oduc s o in e ac ion o he ion beam and he a ge (••e. gems one). Among hem, PIXE (pa icle indiiced X- ay emission) is qui e simila XRF, being based on he de ec ion o X- ay emi ed by he a ge a oms, subsequen o an inne -shell ionisa ion. The only di e ence s ems om he exci a ion sou ce which a cha ged pa icle beam ins ead o a X- ay beam. Fo he PIGE echnique, ac onym o pa icle induccd y- ay emission. he e is no coun e pa . PIGE elies on a nuclea eac ion subsequen o he collision be een an inciden pa icle and a a ge nucleus. Pollowing his eac ion, he nucleus migh emi a y- ay ha ing a speci ic ene gy. On he o he hand, IBA echniques canno be used o iso opic a io de e mina ion ño <^oes i gi e in o ma ion on chemical bonds. F om he poin o iew o gemmology, he IBA echniques exhibi se e al Ín e es ing ea u es. Fi s , in-ai IBA echniques allow in si i and non-des uc i e analysis o 8cms wi hou sample p epa a ion. This haimlessness is a mus o he s udy o a luable obje s such as his o ical jewels. Using simul aneously he PIXE and PIGE me- hods i is possible o de e mine a wide ange o elemen s. PIXE gi es he composi ion o elemen s anging om Na o U, while PIGE use ully ex ends he ange o i-, e ones; F, Be, Li, B. Secondly, he high sensi i i y o hese echniques pe mi s inea- ^u emen o elemen s down o a low le el o concen a ion (e.g. — ppm w ) ansi ion me áis in co undum). Finally, he use o a mic obeam wi h a size o ess han 20-^m allows selec ion o inclusions o hei iden i ica ion. Such a small spo is also use ul o analysing a egión ee o inclusions. Indeed, when using a b oade spo size, he e is always he isk o including an inclusión in he analysed a ea ^a may bias he ace composi ion o he c ys al (e.g. an Fe-con aining inclusión migh lead o a w ong Fe ace con en in a uby). F om he poin o iew o he IBA echniques, gems ones a e ideal samples when compa ed o o he objec s o cul u al he i age such as pain ings o ce amics. They ha e 3 simple, homogeneous composi ion. The sample has a polished and o en ía su ace. Owing o hei e y s able c ys al s uc u e, gems a e nea ly insensi i e o beam e - ec s (no al e a ion). Cha ging o hese usually non-conduc i e a ge s is a oided when using an ex e nal beam se up. 4. EXPERIMENTAL SETUP The expe imen al se up and i s successi e imp o emen s ha e been ho oughly des- c ibed [4]. Only he s iking ea u es will be ecalled he e. The analy ical sys em is based on an ex emal beam line o he AGLAE accele a- o acili y ( igu e 1). The usual 3-MeV p o on beam is ocused down o 30 pm size using magne ic lenses (3 MeV is p o ed o be an op imum ene gy o analysing geo logical samples). This beam is b ough on he sample by passing h ough a e y hin SÍ3N4 oil. The de ec ion o X- ays is achie ed using wo de ec o s. A i s one is dedi- ca ed o ligh elemen s, which a e he majo cons i uen s o he gems ( om Na o Fe). I has a low solid angle, and a minimal il e ing using an ul a hin window combined 200 T. Cmjj(íaho, J.-C. Dk.w. J.-P. Poikoi > G. Qi'e é Figu e I. View o he ex e na! beam Une o he AGLAE accele a o -based IBA acili y. P I wi h a helium low. The second ene is dedica ed o hea y elcmen s ( om Ca o U) a a low le el con ení. I has a high solid angle and a ll e chosen in o de o emo e ma ix X- ays. Gamma- ays a e collec ed using a High Pu i y Ge manium de ec o . The beam is moni o ed using a signal emi ed by he exi oil: backsca e ed p o ons o X- ay line o Si, acco ding o expe imen al equi emen s. 5. applica ion o gems ones We will desc ibe some ecen applica ions o he PIXE and PIGE echniques o an- cien gems om museums pe oimed wi h he AGLAE se up o he Cen e de Reche che e de Res au a ion des musées de F ance. I should be emphasised ha all gems ones s udied he e a e well documen ed and ha e aceable his o y. So we a e con iden ha hese gems a e he o iginal ones. 5.1. Ruby: Ish a 's s a ue e This s a ue e which may ep esen Ish a , a goddess equi alen o Aph odi e, is a pe ec illus a ion o a IBA s udy o gems ones ( igu e 2). The sculp u e is a naked woman ca ed in alabas e , he eyes and na el inlaid wi h ubies. This ema kable piece, which joined he Lou e collec ions in 1866, was exca a ed in he incini y o Babylon in Mesopo amia [5]. Po s ylis ic and ypological easons i is a ibu ed o he Pa hian pe iod (2nd cen u y B.C. o he la e 2nd cen u y A.D.). We we e able o con i m ha he cabochons we e indeed na u al ubies and no colou ed glass, as had been belie ed e en qui e ecen ly, as he wo main cons i uen s o ubies we e e ealed: 99% alumina (AhOd. associa ed wi h less han 1 % ch omium, he elemen esponsible o he cha ac e is ic ed colou o uby. Se e al ace elemen s III CoNGRluSO N a( U)N 1 DI ARGIH)MI TRlA 201 Figu e 2. Ish a in being analysed using he ex e na! beam sys e n ( e cuade niUo a co!o . pág. ^. we e also measu ed, including i anium, anadium, i on, coppe , gallium, all being cha ac e is ic o na u al s ones ( igu e 3). The simila aspec and chemical composi- ion o he h ee inlays sugges he use o a single ba ch o s ones o he s a ue e. In o de o de e mine he geog aphical o igin o his s a ue e's ubies, we unde - ook a compa a i e s udy wi h con empo a y ubies o known p o enance [6]. A o al o o e 500 analyses was ca ied ou on ubies om he main exis ing deposi s: A ghanis an, Myanma (Bumia), Cambodia, India, Kenya, Madagasca . S i Lanka,Thai- land and Vie nam. The ace elemen con en s o he s ones a e qui e di e en de- pending on hei p o enance and a e homogeneous wi hin a gi en deposi , a ea u e absolu ely needed o a p o enance s udy based on geochemis y. Mul i a ia e s a is- 1e5 10000 1000 100 high ene gy X- ay de ec o spec um low ene gy X- ay de ec o spec um TI,, Vk C K Fe 10 15 X- ay ene gy (keV) Figu e 3. X- ay spec a o maja and ace eiemen s eco ded on a ed eye o he s a ue e. 202 T. Caujc.a o. J.-C. D w. J. P. Poi oi > G. Qi'EKR^ ical me hods we e used ( ac o analysis, hie a chical classi ica ion and disc iminan analysis), inco po a ing all he chemical ace elemen s (Ti, V, C , Fe, Ga). All hese analyses con e ge and show ha he s a ue e's ubíes ha c a composi ion e y cióse o ha o ubíes om Bu ma ( igu e 4). The esul s o he geochemícal s udy we e con i med by classícal gcmmological obse a íons conduc ed concu en ly; ín pa icula , he u ile inclusions obsc ed in he eyes and he na el a e consis en wi h a Bu mese o igin. Resea ch ca ied ou on he ubíes o he Pa hian s a ue e om he Lou e com- bining obse a ion o he gems and hei geochemícal cha ac e ísa íon by he PIXE me hod has led o a be e ínsígh ín o hís wo k o a by ídcn í yíng í s cons í uen ma e ials. In addí íon, í has p o íded he oppo uní y o es ablísh a da a base on he composí íons o he main uby deposí s. Fínally, hanks o s a ís ícal analysis, a p o e- nance o he s a ue e's ubíes could be p oposed: Bu ma. I can hus be concluded ha he gems om he Pa hian s a ue e a e e ídence o ade o exchange o e se e al housand kilome es be ween Mesopo amía and Sou h-Eas Asía du íng he Pa hian pe iod. As a as we know, hís ís he ea líes use o ubíes íden í íed lo da e ín hís egión. Thís i gu e o Ish a ís ema kable o í combines ín luences de í íng om h ee ci ílísa íons: Mesopo amía ( he ímage o he naked woman as a é ilí y sym- bol), G eece ( he Hellenís íc ealísm o he body), and ínally Asía ( he p esence o he ubíes). 10000 S s Ó 1000 100 10 g oup III g oup I 10 X : Ish a A: A ghanis an B ; Bu ma C ; Cambodia K; Kenya M ; Madagasca S : S í Lanka T : Thaíiand g oup 100 1000 10000 Fe (ppm) Figu e 4. Plo o C s Fe con ení o he ubíes o he s a ue e and e e ence ubíes. III CoNíikl SO N ac lONM DI ARyi loMMKlA 203 Figu e 5. Royal o i e c own being analysed wi h he e. e nal beani ( e cuade nillo a colo , pdg. i)- 5.2. Emií ald: hi-: Visigo hic easu e We epo he e an applíca íon o he analysis o eme alds o he Gua aza easu e ( igu e 5). Thís amous se o o i e oyal c owns, made o gold wi h ínlaid gem- s ones, da es om he Visigo hic pe iod (7*^-8"' cen u ies). I was exca a ed in 1858 nea Toledo and is now splí ín o wo main pa s kep a he Na ional A chaeological museum ín Mad id, Spain and he Na ional Middle-Ages museum in Pa ís, F ance [7]. The sou ces o eme alds used in ancien Egyp and he Román Empi e a e qui e well documen ed; i is no so o he ea ly Middle-Ages. This wo k aimed a companng an cien eme alds o hose o a ious o igins epo ed in ancien li e a u e (Egyp , Aus ia, A ghanis an, Ou al), on he basis o chemical analysis [8]. PIXE and PIGE ech- niques pe mi ed o iden i y gems ones by means o hei composi ion in majo elemen s (Be, Al, Si) and o de e mine hei ace elemen con en s ( igu e 6). P o enance de- e mina ion elies on he compa ison o hese con en s o hose o e e ence eme alds cons i u ing a da a base o geochemical composi ion. The mos disc imina ing elemen s we e Li, Na, V, Rb and Zn. The measu ed con en s in hese ancien eme alds a e only compa ible wi h Egyp ian (Jebel Zaba a) o Aus ian (Habach al) deposi s ( igu e 7). Since i pe mi ed o disca d al é na e assump ions (e.g. U al, A ghanis an o Pakis án), his wo k p o ided a new insigh in o he ade ou es o gems ones a he ime o he G ea In asions. 5.3. Ga ne : jewels o he i s Kings o F ange Game s belong o a amily o gems ha ing a iable composi ion. The mos com- mon ype is he py alspi e amily wi h he chemical o mula X*^3AP^*2(Si04)í, X be- 204 T. CMJJdAKO, J.-C. D W. J.-P. Po/KOI > G. QdERRÉ Figu e 6. Gamma- ay spec um o an eme ald. Figu e 7. Sun ay plo o ace elemen s con ení o ancien and e e ence eme alds. 10 10 10 10^1 10' 10' iiAL-j kJJ SI I ' I ' ' ■ ' I ' ' ' ■—I ' ■—■—' I ' ■ ' ' I PIGE spec a o an e oe ald Bo 3662 koV iil Li 478 keV F 197 keV 500 1000 1500 2000 2500 3000 3500 4000 GaoMa ay Ene gy (keV) S a islical p ocessing ; Sun ay plo o ace elemen s I /| A ghanís an Pakis án ^Gallo-Roman Columbia _ Zambia ("S Egyp J Wlsigo h Zimbabwe ladagasca No /ay B azil ''Ja / Mg o Rb Ca Re / C ^ V Vaiiaules ing ei he Fe (almandin game ), Mg (py ope game ) o Mn (spessa i e game ), o a combina ion o hem. The ques ion o he na u e, o igin, cu ing and se ing echniques o he game s used in Eu ope du ing he Ea ly Middle Ages is highiy deba ed. A í s a emp o apply IBA echniques o Ea ly Middle Ages game s has been pe - o med in he C2RMF [9]. This wo k deal wi h he iden i ica ion o game s moun ed on Me o ingian jewelle y om Lou es-en-Pa isis. The conclusión was ha hese a - chaeological game s had a majo composi ion compa ible wi h game s om S i Lanka (almandine-py ope ype). We a e cu en ly de eloping a new esea ch p og am on he Me o ingian game s. The aim o his wo k is o include ace elemen and nea -su ace analysis o he gems. III Conc; i_s() Nac iowi di A (,)1 i-.omi- Ia 205 Figu e 8. Me o ingian jewei wi h ga ne s se in cloisonné s yle ( e cuade nillo a colo , pág. i). These ga ne s a e se on he cloisonné jewels ( igu e 8) om he oyal easu e o Sain Denis, F ance, comp ising he amous jewels o Queen A egonde [10]. This wo k will be ex ended wi h he analysis o game s exca a ed om a ious a chaeological si es in Eu ope. 6. CONCLUSION IBA echniques and speci ically he PIXE/PIGE combina ion in ai appea as a- luable ools o analysing gems moun ed on his o ical jewels. They use ully comple- men classical gemmological in es iga ions. The main ad an ages a e 1) comple ely non-des uc i e analysis, 2) b oad ange o elemen s de ec ed, 3) 0- 4m size spa ial esolu ion 4) ppm le el sensi i i y and 5) good accu acy. They we e applied o de e mine he na u e and p o enance o ancien mbies. Fo Middle Ages eme alds and ga ne s, he esul s al eady ob ained a e p omising. Mo e e e ence da a a e needed and he combina ion wi h o he analy ical echniques has o be ied. 7. REFERENCES [1] Ande son, B.W. and Jobbins, E.A., 1990, Gem es ing, Bu e wo hs, London. [2] Bi d, J.R. and Williams, J.S., 1989, Ion beams o ma e ials, Academic P ess, London. 206 T. Caumíamo. J.-C. Dka.s. J -I*. I^oihoi > G. Que é [3] Campbell, J.L. and Malmq is , K.G., 1995, Pa icle-induced X- ay spccí ome y (PIXE), John Wiley & Sons, Lxjndon. [4] Calliga o, T., D an, J.-C., Hamon, H., Moigna d, B. and Salomón, J.. 1998, An exlemal milli-beam o a chaeome ic applica ions on ihe AGLAE IBA acili y o he Lou e mu- seum. Nucí. Ins . and Me h. B 136/138, 339-343. [5] Tallen, F., 1999, Ac es du colloque: Comaline c pie cs p ccieu.scs - 1995, Musée du Lou e, Pa is. [6] Calliga o, T., Mossmann, A., Poi o , J.-P. and Que é, G., 1998, P o enance s udy o u bíes om a Pa hian s a ue e by PIXE analysis. Nucí, hus . and Me h. B 136/138, 846- 850. [7] Pe ea, A. and Balmaseda, LJ., 1999, Las es his o ias del eso o de Gua aza y el p oyec o Au, Re is a de a queología 221, 37-45. [8] Calliga o, T., D an, J.-C., Poi o , J.-P., Que é, G., Salomen, J. and Zwaan, J.C., 2000, PDCE/PIGE cha ac e isa ion o eme alds using an ex emal mic obeam. Nucí. In.s . and Me h. B161/163, 769-774. [9] Fa ges, F., 1998, Mine alogy o he Lou es Me o ingian game cloisonné jewel y: O i- gins o he gems o he i s kings o F ance, Am. Mine al 83, 323-330. [10] Fleu y, M. and F ance-Lano d, A., 1998, Les é.so s mé o ingiens de la basilique de Sain -Denis, Gé a d Klopp eds, Woippy, F ance. APROXIMACIÓN AL ESTUDIO DE PROCEDENCIA Y TECNOLOGÍA DE FABRICACIÓN DE LAS CERÁMICAS CAMPANIFORMES DEL YACIMIENTO DE LA EDAD DEL COBRE DE LOS MILLARES Jose a Capel''', Fenia ido Molina'", T inidad Náje a*", José Lina es'-' V F ancisco Hue as'" Resumen En es e abajo se lle a a cabo el es udio analí ico median e Espec ome ía de Masas, Di acción de Rayos-X y Mic oscopio Es e eoscópico de un conjun o de asijas ce ámicas de es ilo campani o me p oceden es del yacimien o de la Edad del Cob e de Los Milla es. El análisis químico se ha cen ado en el es udio de los elemen os denominados ie as a as que cons i uyen un indicado exce len e del o igen de los ma e iales. El es udio mine alógico así como la obse a ción óp ica han apo ado in o mación sob e p ocesos ecnológicos de manu ac- u ación. Palab as cla e: ce ámica. Edad del Cob e, p ocedencia, manu ac u ación. 1. INTRODUCCIÓN Los abajos sob e la mo ilización de elemen os químicos du an e los p ocesos de hid ólisis y al e ación de ocas ocupa un impo an e campo en la in es igación desa ollada en el ámbi o de las ciencias del suelo y ciencias de la Tie a en gene al. La mayo o meno mo ilidad de es os elemen os, en el caso de los mine ales, es á in l uenciada po la es uc u a del c is al. Es igualmen e ob io que exis en nume osos ac o es isicoquímicos ales como pH, empe a u a y p esión de la solución, ex u a y pe meabilidad de los sólidos, á ea supe icial, e c., que in luyen de igual o ma. No obs an e un mismo elemen o puede compo a se, dependiendo de su posición c is alo- Dp o. de P ehis o ia y A queología. Facul ad de Le as. Campus Uni e si a io de Ca uja, 18071 G anada Dp o. de Ciencias de la Tie a y Geoquímica Ambien al. Es ación Expe imen al del Zaidín, CSIC. P o eso AIba eda, s/n, 18008 G anada.