Nuclear Instruments and Methods in Physics Research B 273 (2012) 173–177

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Nuclear Instruments and Methods in Physics Research B

journal homepage: www.elsevier .com/locate /n imb

Non-destructive provenance differentiation of prehistoric pigments by external PIXE

L. Beck a,⇑, H. Salomon b, S. Lahlil a, M. Lebon a,c, G.P. Odin a, Y. Coquinot a, L. Pichon a

a C2RMF-UMR171 Centre de Recherche et de Restauration des Musées de France, 14 quai François Mitterrand, Palais du Louvre Porte des Lions, 75001 Paris, Franceb Centre Européen d’Archéométrie, Université de Liège, Sart Tilman Bât B15, 4000 Liège, Belgiumc Muséum National d’Histoire Naturelle, Département de Préhistoire, UMR 7194, 1 rue René Panhard, 75013 Paris, France

a r t i c l e i n f o

Article history:Available online 26 July 2011

Keywords:PIXEPrehistoric pigmentOchreProvenancePetrographyArcy-sur-Cure

0168-583X/$ - see front matter � 2011 Elsevier B.V.doi:10.1016/j.nimb.2011.07.068

⇑ Corresponding author. Present address: CEA, DEMétallurgie Physique, Laboratoire JANNUS, 91191 Gif

E-mail address: lucile.beck@cea.fr (L. Beck).

a b s t r a c t

The elemental analysis of minerals/rocks has been often used for the determination of their geologicalorigin. When these natural rocks were exploited by prehistoric civilizations as objects, weapons, or pig-ments, the composition of the minerals can provide information on the mobility, the exchanges and theinteraction between groups of population. In this paper, we will present results obtained from archaeo-logical samples of prehistoric pigments, mainly iron and manganese oxides. PIXE analysis has beenapplied to samples of the prehistoric cave ‘‘La grotte du Renne’’ in Arcy-sur-Cure, France (Chatelperro-nian, 38,000–34,000 BP). Because most of the archaeological objects are decorated or display some usemarks, it is not possible to take samples. Consequently, we have used a non-destructive technique thanksto the external beam of AGLAE (C2RMF, Paris). In order to improve the limits of detection (LOD less than10 ppm from Cu to Sb), a metal absorber has been placed on the X-ray detector to preferentially filter theFe–K or Mn–K lines.

Based on the quantitative analysis of major and trace elements, we have obtained groups of composi-tions corresponding to different geological sources. We demonstrate in this study that it is possible toextend PIXE analysis to the characterization of prehistoric pigments such as iron and manganese oxidesfor differentiating potential sources of pigments in archaeological contexts.

� 2011 Elsevier B.V. All rights reserved.

1. Introduction

In the past years, Particle Induced X-ray Emission (PIXE) has lar-gely demonstrated to be a powerful tool capable of analyze traceelements for determining the provenance of archaeological materi-als. It has been mostly applied to geological based material such asobsidian [1–3] and gems [4–6]. In these cases, raw materials havebeen employed by ancient civilizations without (or with minor)transformation and it is admitted that the initial chemical compo-sition is not (or slightly) affected [7]. This is particularly recognizedfor trace elements which can be used as fingerprint of geologicalsources and thus contribute to provenance investigations. Thispoint is an important question for historical and prehistoric stud-ies, as it allows tracing commercial routes and cultural exchangesbetween ancient communities.

Recent papers have focused on the study of trace elements inpigments or in raw materials from geological sources by LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrome-try) [8–10], PIXE [11–15] and neutron activation analysis [16,17].Except Refs. [13–15] all the mentioned studies have required sam-ple preparation which is not always possible for archaeological

All rights reserved.

N, Service de Recherches de-sur-Yvette, France.

artefacts. In this paper, we present experimental PIXE configura-tions which allow investigating prehistoric pigments, mostly ironand manganese oxides, at the ppm level without any preparationor sampling. In order to assess the feasibility of this procedure tothe study of pigment procurement, we have applied it to the pre-historic site of Arcy-sur-Cure, France (38,000–34,000 BP) [18,19].

2. Experiment

2.1. Pigment samples

Samples are composed of blocks of pigments found in the cha-telperronian layers (38,000–34,000 BP) of la Grotte du Renne inArcy-sur-Cure, France. This site represents the richest archaeolog-ical sequence evidencing the late Neanderthal activities beforetheir complete disappearance. The excavations, conducted by And-ré Leroi-Gourhan in the 60s, revealed a large amount of colouringmaterials, mainly red or black. More than 18 kg of colouring mate-rials, i.e. about 2000 fragments and 300 worked objects were asso-ciated with fireplaces and remains of two huts, which were builtwith calcareous stones and mammoth tusks. All these observationsindicate intense production of powder either by crushing andgrinding, or by scraping and abrading. This last category of arte-facts reveals consequently polished or striated surfaces (Fig. 1).

Fig. 1. Some blocks of pigments and worked tools (mainly in iron oxide (red) or in manganese oxide (black)) found in the chatelperronian layers (38,000–34,000 BP) of LaGrotte du Renne in Arcy-sur Cure, France. (For interpretation of the references to colours in this figure legend, the reader is referred to the web version of this paper.)

174 L. Beck et al. / Nuclear Instruments and Methods in Physics Research B 273 (2012) 173–177

Due to the presence of marks on these worked tools which testifyof their use, it is not allowed to take sample for analysis. Objectsare consequently directly analysed without any kind of prelimin-ary treatment or preparation.

2.2. PIXE experimental setup: external beam and selective absorbers

PIXE experiments were conducted at the AGLAE (AccélérateurGrand Louvre d’Analyse Elémentaire, Paris, France) facility usinga 3 MeV proton extracted beam. The beam size is about 50 lmdiameter. Because the samples are highly inhomogeneous, theywere scanned in order to average over a 1 mm2 area. Objects werejust set on the XYZ table in front of the extracted beam exit. Precisepositioning is achieved by using the luminescence induced by theproton beam on the sample minerals. X-ray spectra are recordedby two Si(Li) detectors oriented at 45� to the beam [20,21]. Oneis devoted to low energy X-rays (0.1–15 keV) from major elementsof the matrix, mainly Fe or Mn, Al, Si and Ca. The other detector isequipped with selective filters to reduce pileup by attenuating in-tense X-rays [22]. We have selected absorber according to the ma-trix major element. For iron based matrix, a 20 lm thick chromiumabsorber was mounted on the detector whereas for manganesebased matrix, a vanadium absorber was used. An additional50 lm thick aluminium filter was superimposed in order to reduceCr or V X-rays induced by the interaction of the primary X-rayscoming from the sample with the absorber.

PIXE spectra were collected between 10 and 15 min (Fig. 2). Ele-mental concentrations have been extracted by using GUPIX [23]and TRAUPIXE [24]. Thanks to this experimental procedure, limitsof detection less than 10 ppm have been achieved for most of traceelements (Table 1). These values are of the same of order of mag-nitude as in other studies by NAA or PIXE where samples werepowdered and prepared.

3. Results

3.1. Mineralogical and petrographical characterization of the pigments

Based on mineralogical studies, Salomon et al. [19] have dem-onstrated that the red pigment materials found in the cave ofArcy-sur-Cure have three different geological provenances (A–C

groups). These results were obtained after a first mineralogicaldetermination by X-ray diffraction on a sampling of 80 blocks.Then, nine blocks without any past modification tracks were cutin order to prepare 30 lm thin sections studied with a petro-graphic microscope. Four groups are described as follow:

Group Aa: ferrugineous hardground. This rock is characterizedby benthic organisms, mainly crinoid segments and urchin remainscemented by haematite, goethite and calcite. Its formation is theresult of an abrupt interruption of sedimentation lasting many mil-lion years.

Group Ab: this group presents the same morphology as GroupAa, with a slight difference due to the dissolution of the carbonatephase. Small bone fragments were also identified. This pigment isformed in the same geological layer with the ferrugineous hard-ground but this part of the formation was submitted to wateractivity.

Group B: ferrugineous sandstone/siltstone. This rock is charac-terized by 40–90% rounded quartz grains cemented by haematiteor a mix of haematite and goethite.

Group C: blocks of almost pure haematite. The lack of internalstructure within the blocks did not allow the identification of thegeological formation from which they were extracted.

For black pigment materials, the results obtained by this firstapproach tend to show that the oxides and hydroxides of manga-nese form a homogeneous corpus (Group D) of black pigmentsalong the whole archaeological assemblage.

The study of the geological map and the research in the miningarchives have documented the possible catchment area for thesefour minerals. The groups Aa and Ab are located around 40 km eastto the site in the Hettangian formations (beginning to the Jurassic),whereas the group B has been identified in the Mio-Pliocene for-mation covering the tablelands next to the cave, around 4–40 kmwest. For the groups C and D, no geological layer in the area ofArcy-sur-Cure is documented.

3.2. PIXE for iron oxide pigments

Twenty-seven samples corresponding to13 worked tools and 14blocks were analyzed by PIXE. Around 20 of these samples were al-ready characterized by petrography and/or XRD (see Section 3.1) tobe used as group references. Concentrations have been obtained

1

10

100

1000

10000

100000

1000000

0 5 10 15 20 25 30 35 40

Energy (keV)

1

10

100

1000

10000

100000

1000000

0 5 10 15 20 25 30 35

1

10

100

1000

10000

100000

1000000

0 5 10 15 20 25 30 35 40

(keV)

1

10

100

1000

10000

100000

0 5 10 15 20 25 30 35 40

Cou

nts

Cou

nts

Ca

Si Fe

pile up

Ba Sb

Mo Zr Sr

Rb

As

Zn

Fe Mn

1- Low X-ray energy detector

2- High X-ray energy detector with 20 µm Cr and 50 µm Al

(a)

(b)

Fig. 2. Typical PIXE spectra for prehistoric pigments composed of (a) iron oxide or(b) manganese oxide. 1—Low X-ray energy detector (in blue). 2—High X-ray energydetector (in red) equipped with a 20 lm thick selective filter and 50 lm Al. Theselective filters are Cr for iron matrix and V for manganese matrix. [Spectra ref:09jun016-R437 and 18oct015- R598]. (For interpretation of the references tocolours in this figure legend, the reader is referred to the web version of this paper.)

Tabl

e1

PIX

Elim

its

ofde

tect

ion

(LO

D)

for

elem

ents

heav

ier

than

iron

.

Co

Ni

Cu

ZnG

aA

sR

bSr

YZr

Mo

SnSb

Ba

LaC

eTl

LPb

L

Iron

oxid

em

atri

x(t

his

stu

dy)

57–1

0019

73

312

22

34

37

824

18–4

5Ir

onox

ide

mat

rix

[12]

30–5

48–

95–

103–

42–

41–

31–

21–

21–

21–

22–

84–

103–

9M

anga

nes

eox

ide

mat

rix

(th

isst

udy

)14

517

117

612

32

410

311

1456

6077

2226

–80

L. Beck et al. / Nuclear Instruments and Methods in Physics Research B 273 (2012) 173–177 175

for major and trace elements. Due to the irregular distribution offossil remains, totally or partially preserved, Fe and Ca cannot beused to characterise the pigments. However, the Si:Al ratio givesinformation on the alumino-silicate phase (Fig. 3). The alumino-sil-icate phases for groups Aa and Ab are composed of the same claymineral. Group B shows a high Si content which is due to the largeamount of quartz. Group C is not well defined.

In order to establish geochemical groups relative to iron oxide,bivariate plots of iron and trace elements have been performed.Among the 15 detected trace elements, three of them (Mo, Asand Sb) are correlated to iron with different ratios according to

y = -2.2194x + 635203

R2 = 0.221

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

0 20000 40000 60000 80000 100000

120000 140000 160000

Al2O3

SiO2

y = 2.65x R² = 0.92

Aa

Ab

C

B

Fig. 3. SiO2 concentration as a function of Al2O3 concentration (in weight%) forprehistoric pigments composed of iron oxide (Arcy-sur Cure, France).

Fig. 5. SiO2 concentration as a function of Al2O3 concentration (in weight%) forprehistoric pigments composed of manganese oxides-hydroxides (Arcy-sur Cure,France).

176 L. Beck et al. / Nuclear Instruments and Methods in Physics Research B 273 (2012) 173–177

the geological group (Fig. 4). Group C is characterized by a highcontents of Mo, As and Sb. Groups Aa and Ac have the same con-tents of As, Sb and Mo with intermediate values, confirming thesame geological origin. Group B has very low content in trace ele-ments. These bivariate plots corroborate the source distinctionbased on petrographic analysis, only performed on non-workedblocks. Thanks to the PIXE results, it has been possible to precisedoubtful attribution of several archaeological samples. In particu-lar, some attributions previously obtained by optical observationand XRD were changed and two unidentified worked tools wereattributed to group B and group C (Fig. 4).

These results provide strong evidence that iron oxide sources inthe Arcy-sur-Cure area can be discriminated using external PIXE.

3.3. PIXE for manganese oxide pigments

All the black pigment samples contain more than 70 wt% ofmanganese oxide. Other major elements such as Si or Al can be

0

100

200

300

400

500

600

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800

0 200000 400000 600000 800000 1E+06

Fe2O3

As

0

100

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300

400

500

600

700

800

900

0 200000 400000

Fe2

Mo

1

10

100

1000

10000

0

Fig. 4. Concentration (in ppm) of Mo, As, Sb trace elements as a function of the concunidentified samples (photographies) have been attributed by PIXE to groups B and C.

present in amounts not exceeding 10 wt%. Fig. 5 shows these oxi-des are closely correlated showing the homogeneity of the corpusof samples. The minor and trace elements (Ce, Co, La, Y, Sr, Ni, Zn,Cu, As, Zn, Mo) confirm this result. Four of them are presented inFig. 6. These data further demonstrate the uniformity of the man-ganese oxide corpus and evidence a common origin for all the sam-ples studied.

4. Conclusion

External PIXE has been applied to analyse prehistoric blocks ofred and black pigments. Due to the archaeological importance ofthe artefacts (38,000–34,000 BP), the analysis was performed di-rectly on the samples, without any kind of preparation. The useof selective filters has given access to limits of detection less than10 ppm for iron-based pigments as well for manganese-based pig-ments. The quantification of trace elements provides chemical

1E+06

Fe2O3

600000 800000 1E+06

O3

200000 400000 600000 800000

Sb

Aa

Ab

C

B

entration in Fe2O3 for the prehistoric red pigments of Arcy-sur Cure, France. Two

Fig. 6. As, Cu, Zn trace elements as a function of MnO2 for the prehistoric black pigments of Arcy-sur Cure, France.

L. Beck et al. / Nuclear Instruments and Methods in Physics Research B 273 (2012) 173–177 177

markers which allow establishing distinctions between differenttypes of red pigments.

These results provide strong evidence that prehistoric pigmentsources can be discriminated using external PIXE. It is one of themain archaeological issues, in particular in the field of the chrono-logical attribution of rock art and in the determination of colouringprovenance.

References

[1] L. Bellot-Gurlet, G. Poupeau, J. Salomon, T. Calligaro, B. Moignard, J.-C. Dran, J.-A. Barrat, L. Pichon, Nucl. Instrum. Meth. B 240 (2005) 583–588.

[2] T. Calligaro, J.-C. Dran, S. Dubernet, G. Poupeau, F. Gendron, E. Gonthier, O.Meslay, D. Tenorio, Nucl. Instrum. Meth. B 240 (2005) 576–582.

[3] D. Juárez-Cossío, E. Terreros, J. Quiroz-Moreno, S. Romero-Sánchez, T. Calligaro,D. Tenorio, M. Jiménez-Reyes, M. De Los Rios, Nucl. Instrum. Meth. B 267(2009) 1149–1152.

[4] T. Calligaro, A. Mossmann, J.-P. Poirot, G. Querré, Nucl. Instrum. Meth. B 136-138 (1998) 846–850.

[5] T. Calligaro, J.-P. Poirot, G. Querré, Nucl. Instrum. Meth. B 150 (1999) 628–634.[6] T. Calligaro, S. Colinart, J.-P. Poirot, C. Sudres, Nucl. Instrum. Meth. B 189 (2002)

320.[7] L. Wilson, A.M. Pollard, The provenance hypothesis, in: D.R. Brothwell, A.M.

Pollard (Eds.), Handbook of Archaeological Sciences, John Wiley and Sons Ltd,Chichester, UK, 2001, pp. 507–517.

[8] M. Gil, M.L. Carvalho, A. Seruya, A.E. Candeias, J. Mirão, I. Queralt, Nucl.Instrum. Meth. A 580 (2007) 728.

[9] R.L. Green, R.J. Watling, J. Forensic. Sci. 52 (2007) 851.[10] E. Iriarte, A. Foyo, M.A. Sánchez, C. Tomillo, J. Setién, Archaeometry 51 (2009)

231.[11] B. David, E. Clayton, A.L. Watchman, Aust. Archaeol. 36 (1993) 56–57.[12] P. Nel, P.A. Lynch, J.S. Laird, H.M. Casey, L.J. Goodall, C.G. Ryan, R.J. Sloggett,

Nucl. Instrum. Meth. A 619 (2010) 306–310.[13] M. Sanchez del Rıo, P. Martinetto, C. Solıs, C. Reyes-Valerio, Nucl. Instrum.

Meth. B 249 (2006) 628–632.[14] L. Beck, M. Lebon, L. Pichon, M. Menu, L. Chiotti, R. Nespoulet, P. Paillet, X-Ray

Spectrom. 40 (2011) 219–223.[15] M. Lebon, L. Beck, S.Grégoire, L. Chiotti, R. Nespoulet, M. Menu, P. Paillet, Open

J. Archaeometry, in press.[16] R.S. Popelka-Filcoff, J.D. Robertson, M.D. Glascock, C. Descantes, J. Radioanal.

Nucl. Chem. 272 (2007) 17–27.[17] R.S. Popelka-Filcoff, E.J. Miksa, J.D. Robertson, M.D. Glascock, H. Wallace, J.

Archaeol. Sci. 35 (2008) 752–762.[18] C. Couraud, Galia Préhistoire 33 (1991) 17–52.[19] H. Salomon, C. Vignaud, Y. Coquinot, S. Pagès-Camagna, M.-P. Pomiès, J.-M.

Geneste, M. Menu, M. Julien, F. David, Technè (2009).[20] T. Calligaro, J.D. MacArthur, J. Salomon, Nucl. Instrum. Meth. B 109/110 (1996)

125.[21] J. Salomon, J.-C. Dran, T. Guillou, B. Moignard, L. Pichon, P. Walter, F. Mathis,

Nucl. Instrum. Meth. B 266 (2008) 2273.[22] C.P. Swann, S.J. Fleming, Nucl. Instrum. Meth. B 49 (1990) 65.[23] J.L. Campbell, N.I. Boyd, N. Grassi, P. Bonnick, J.A. Maxwell, Nucl. Instrum.

Meth. B 268 (2010) 3356.[24] L. Pichon, L. Beck, Ph. Walter, B. Moignard, T. Guillou, Nucl. Instrum. Meth. B

268 (2010) 2028.