Mediterranean trade of the most widespread Roman volcanic millstones from Italy and petrochemical markers of their raw materials

This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institution

and sharing with colleagues.

Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third party

websites are prohibited.

In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further information

regarding Elsevier’s archiving and manuscript policies areencouraged to visit:

http://www.elsevier.com/copyright

Author's personal copy

Review

Mediterranean trade of the most widespread Roman volcanic millstones fromItaly and petrochemical markers of their raw materials

Fabrizio Antonelli*, Lorenzo LazzariniLaboratorio di Analisi dei Materiali Antichi (LAMA) e Dip. Storia dell'Architettura, Università IUAV di Venezia, San Polo 2468, 30125 Venice, Italy

a r t i c l e i n f o

Article history:Received 29 October 2009Received in revised form6 February 2010Accepted 15 February 2010

Keywords:Mediterranean tradeItalyAlgeriaCuiculRoman millstonesLavasPetrographyProvenancing

a b s t r a c t

The petrochemical study of millstones can contribute to improve the archaeological research intoreconstruction of ancient communication routes and trade networks. Volcanic rocks are geographicallyrestricted and rather rare in the Mediterranean regions, and during the Roman period Italian volcanoeswere important sources of raw materials for millstones, so the task of determining their geological originis relatively straightforward. The Italian vesicular volcanics most frequently employed for this purposewere: trachytes from Euganean Hills (Veneto), leucite-bearing lavas from the Vulsini Volcanic District(Latium), basic-intermediate leucite-bearing lavas from Somma-Vesuvius (Campania), silica undersatu-rated lavas from Monte Vulture Volcano (Basilicata), a rhyolitic ignimbrite from Sardinia and basicproducts from Mount Etna and the island of Pantelleria (Sicily). This paper contains a general outline ofthe trade network for each volcanic typology used for millstones during the Roman period e updatedwith data concerning the leucite-bearing lavic items discovered in the archaeological sites of the ancientCuicul (now Djemila, Algeria) e together with a summary of their petrographic and geochemical features.

� 2010 Elsevier Ltd. All rights reserved.

1. Introduction

It is generally acknowledged that archaeometric research onmills and millstones found in the Mediterranean area is animportant means for the identification of the production sites ofthese artefacts and for the rediscovery of important trade networksof protohistory and history. During the Roman age, hourglass-shaped or flat, cylindrical rotary millstones were exported to andimported from many provinces of the Empire, including Germany,France, Italy, Spain, Portugal, Morocco, Tunisia, Libya, Algeria,Cyprus and Turkey (cf. Williams-Thorpe, 1988; Antonelli et al.,2001, 2005 and bibliography therein). Most of these Roman mill-stones discovered in archaeological sites throughout the Mediter-ranean are made of volcanic rock. In fact, lavas are generally wear-resistant and they are particularly suitable for milling because oftheir abrasive property (hard enough not to contaminate the flourunduly) and rough vesicular surface that provides a good grindingcapacity. The mills most commonly used by the Romans were up to1.5 metres high (Fig. 1) and typically consisted of an hourglass-shaped (double-cone) upper stone (catillus) resting on the conicallower stone (meta) (Moriz, 1958). The catillus was turned on themeta by means of a bar pushed by slaves or a donkey (mola asinaria

or iumentaria; donkeymills). As proposed by Antonelli et al., 2001,re-interpreting Varro (the Latin scholar of the first century BC)rotary millstones (molae versatiles) were most probably invented(no later than the fourth century BC) in Volsinii veteres (present-dayOrvieto), the famous Etruscan village, and not simply in Volsinii(or Volsinii novi, now Bolsena), the Roman city built in the first halfof the third century BC close to Bolsena Lake, ca 8 km NE of Orvieto.Rotary millstones hourglass-shaped are also known as Pompeian-style millstones after the site where they occur so frequently andwere first discovered (i.e. Pompeii-Naples; Peacock, 1989; Buffoneet al., 2003). Other famous Italian archaeological sites wherewell-preserved examples have been discovered include OstiaAntica (Rome) and Aquileia (Udine). They were a very popular item,highly prized in Roman bakeries and military settlements of theImperial provinces. Shipwrecked cargoes of millstones such as thatof Sec (Mallorca, Spain; Williams-Thorpe and Thorpe, 1990), testifyboth to their importance in the Roman period and to the fact thatthey were traded throughout the eastern and western Mediterra-nean. Fortunately, seeing that volcanic complexes occur in fewregions of the Mediterranean basin, volcanic rocks exploited formillstones may be very important markers for reconstruction ofancient commercial and communication routes. Old and recentworks (Peacock, 1980, 1986, 1989; Ferla et al., 1984; Williams-Thorpe, 1988; Williams-Thorpe and Thorpe, 1989, 1990, 1991,1993; Lorenzoni et al., 1996, 2000a,b; Oliva et al., 1999; Antonelli

* Corresponding author.E-mail address: [email protected] (F. Antonelli).

Contents lists available at ScienceDirect

Journal of Archaeological Science

journal homepage: http : / /www.elsevier .com/locate/ jas

0305-4403/$ e see front matter � 2010 Elsevier Ltd. All rights reserved.doi:10.1016/j.jas.2010.02.008

Journal of Archaeological Science 37 (2010) 2081e2092

Author's personal copy

et al., 2000, 2001, 2004, 2005; Renzulli et al., 2002a; Santi et al.,2004; Buffone et al., 2003) have combined to establish a usefulpetrographic, geochemical and historical database on the sourceareas for the grinding tools used in Mediterranean countries fromthe Neolithic to the Roman periods.

The purpose of this paper is to give a concise overview of themain Italian volcanic rocks exploited by the Romans in the manu-facture of exported millstones as well as of their trade network. Thegeneral outline is updated with new data referring to leucitephonolite mills discovered at the archaeological site of ancientCuicul (now Djemila, Algeria) (cf. Figs. 4e6 and Table 1).

2. Quarrying areas and circulation of the artifacts

The Romans exploited several Italian lava sources (Fig. 2),generally vesicular and so relatively easy to work, to producemillstones and rotary querns; judging by the archaeological findsthe most widespread were (from northern to southern Italy): (i)Na-trachytes from the Euganean Hills (Padua e Veneto); (ii) leucitephonolites from quarries in the Vulsini Volcanic District (nearOrvieto e Latium); (iii) leucite basaltic trachyandesites of Somma-Vesuvius (Naples e Campania) and (iv) tephrites-foidites fromVulture (Potenza e Basilicata); (v) volcanic rocks from Sardinia,

chiefly rhyolitic ignimbrite from Mulargia and, to a very minorextent, the grey vesicular subalkaline basalts from different parts ofthe island (not considered here); (vi) hawaiites, mugearites andbasalts from Etna (Catania e Sicily) as well as, to a minor extent,some other Sicilian basic lavas from Hyblean Plateau and theislands of Pantelleria, Ustica and Lipari. However, according to thearchaeological and archaeometric evidence, volcanics (iii), (v) and(vi) were generally preferred by Romans for export on a medium-large scale, (i)e(ii) were exported on a medium-to-small scale,whereas the lavas from Vulture (iv) were seldom transported farfrom the production centres and basically employed locally and ona small scale.

2.1. Trachytic rocks from the Euganean Hills e Venetian VolcanicProvince

The Euganean Hills, located in North-Eastern Italy (province ofPadua) within the Venetian Tertiary Volcanic Province, comprise 81domes whose origin is related to the extensional tectonic regime ofthe South-Alpine foreland (De Pieri et al., 1983) and the extensiveeruptive activity that took place from the late Paleocene to the late

Table 1Whole rock major oxides (wt%) and trace elements (ppm) analyzed for Roman lavicmillstone D, D3, D4 discovered in the archaeological site of the ancient Cuicul(Djemila, Algeria). An average (OR-AV) of 11 analyses (of leucite phonolite lavas fromthe Orvieto quarries (after Antonelli et al., 2001) is reported for the purposes ofcomparison. Standard-deviation (s) of the average values OR-AV with respect to thequarry samples of Antonelli et al. (2001) are also reported. Analyses were performedat the ALS Chemex Laboratory Group (Vancouver, Canada) by ICP-OES-MS methods.Errors were �1% for major oxides and �5% for trace elements.

Sample D D3 D4 OR-AV s

wt%SiO2 55.20 54.60 54.00 56.35 0.36Al2O3 20.00 18.60 19.85 21.42 0.13Fe2O3 4.37 3.77 3.41 4.37 0.15MnO 0.16 0.14 0.13 0.13 0.01MgO 0.83 0.71 0.79 0.81 0.03CaO 3.84 4.86 4.91 3.57 0.09Na2O 2.98 3.27 2.63 2.79 0.42K2O 8.48 8.25 10.55 9.95 0.30TiO2 0.53 0.47 0.41 0.50 0.02P2O5 0.13 0.16 0.25 0.10 0.01LOI 2.86 2.85 2.78 e e

Total 99.38 97.68 99.71 99.99 e

K2O/Na2O 2.85 2.52 4.01 3.57 e

ppmV 143 120 114 125 19.45Cr <10 <10 <10 2.67 1.0Co 6.50 5.70 5.80 5.56 0.3Ni <5 <5 <5 4.00 0.9Rb 278 282 396 352 40.0Sr 2100 2170 1865 1947 61.0Y 39 35 30 39 1.6Zr 811 649 558 730 69.0Nb 54.1 48.0 36.6 45.0 1.9Ba 2300 2430 2120 2232 44.0La 204 183 144 183 7.0Ce 394 316 255 325 12.0Nd 121 108 87 107 4.0Sm 18.05 16.05 13.10 16.10 0.50Gd 17.00 15.00 12.15 11.30 0.60Dy 8.17 7.20 6.04 7.18 0.32Er 4.61 4.22 3.38 3.42 0.13Yb 4.05 3.64 2.96 3.35 0.12Lu 0.57 0.52 0.42 0.51 0.02Hf 13.10 11.60 9.50 10.80 0.40Th 144 126.5 95.6 160 9

Fig. 1. Classical Pompeiian-style millstones. (a) Pistrinum of Pompeii; (b) Aquileia,Archaeological Museum; (c) Pistrinum of Ostia Antica.

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e20922082

Author's personal copy

Fig. 2. Geographic location of the main Italian volcanic rock source areas exploited by the Romans to manufacture millstones. 1. Euganean Hills: general map after Capedri et al.,2000. Letters and numbers in bold are related to the sites chemically analyzed by Capedri et al., 2000. 2. Roman Magmatic Province: draft of the outcrops and exploited sources ofvolcanic products (after Buffone et al., 2000, modified). 3. Sardinia: sketch map of showing the distribution of OligoceneeMiocene (diagonal lines) and PlioceneePleistocene(stippled areas) volcanic rocks (after Williams-Thorpe and Thorpe, 1989; modified). 4. Mt. Etna Volcano: sketch map showing the distribution of the main units (after Cristofoliniet al., 1991, modified). (1) Sedimentary basal levels; (2) Tholeiites; (3) Ancient Na-alkalic deposits (basalts and hawaiites dating back to 225 ky before present); 4) Trifoglietto Unit(mugearites); (5) Detrital alluvial fan originated from the Valle del Bove; (6) Elliptical volcano deposits (Mongibello Unit; hawaiites to trachytes); (7) Recent Mongibello (hawaiitesand mugearites); (8) Edge of the Valle del Bove; (9) Major faults.

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 2083

Author's personal copy

Oligocene. Volcanic and sub-volcanic products range from subor-dinate basalts to intermediate and acidic lithotypes, mostlytrachytes and rhyolites with a moderate Na-alkaline magmaticaffinity. The latter crop out in the central part and at the edge of thearea respectively and testify to the change in magmatic activity inthe Lower Oligocene (Zantedeschi, 1994). Euganean Trachytes havebeen among the most widely distributed stones of NE Italy sinceancient times. They were already used by the Paleo-Venetianpopulations in the seventh century BC for stelae (preserved in theArchaeological Museums of Este and Padua) and mills (Antonelliet al., 2004). The Romans occupying the Po Valley from thesecond century BC used it much more abundantly for the samepurposes and for architectural elements (columns, capitals, lintels,pillars, etc.), water pipes, bridges and to pave Venetian, Istrian andEmilian roads (several sections of the Via Aemilia were paved withpolygonal trachytic blocks; Renzulli et al., 1999, 2002b). In Romantimes the stone also reached distant towns such as Ticinum (Pavia)(Tozzi and Oxilia, 1981), Mediolanum (Milan), Tergeste (Trieste),Fanum Fortunae (Fano; Renzulli et al., 1999) and Ankon (Ancona;Renzulli et al., 1999): these towns form a triangle within whichtrachyte is very often found. In the same period, Euganean trachyticmillstones and rotary-millstones were manufactured and spreadthroughout the X Regio Augustea, Venetia et Histria (Antonelli et al.,2004; Antonelli and Lazzarini work in progress) also reaching somelocalities of ancient Aemilia and Picenum (Marche) regiones (i.e.,Fossombrone and Urbisaglia e Renzulli et al., 2002a; Santi andRenzulli, 2006). Among the 70 open-pit trachyte quarries identi-fied in the field by Capedri et al. (2000), the sites where exploitingactivity was particularly important were Monselice, Monte Rosso,Monte Oliveto, Monte Merlo, Monte Lispida, Monte Alto and MonteAltore (Fig. 2). The trade towards the south was quite easy to carryout (especially from the Monselice area) along the Mid-Adriaticcoast and also throughout a system of drainage channels joining thehills to the paleo-Adige and the Brenta Rivers (Renzulli et al., 1999,2002b), while the connections between Euganean sources and theregions to the east could be effected by using the fluvial andmaritime routes that had operated in this part of Caput Adriae sinceprotohistoric times.

2.2. Leucite phonolite from Orvieto e Vulsini Volcanic District

In the Mediterranean area, the use of leucite-bearing lavas wasparticularly widespread. Millstones and rotary querns producedfrom these lavas have been discovered in Italian archaeologicalsites (e.g., Aquileia e unpublished data e Luni, Veio, Ostia,Ercolano, Pompeii, Paestum and in Sicily; Antonelli et al., 2001;Santi et al., 2004 and bibliography therein) as well as in otherMediterranean regions such as Iberia, France, Cyprus, Tunisia,Tripolitania, Cyrenaica (Peacock, 1980, 1986; Williams-Thorpe,1988; Oliva et al., 1999; Antonelli et al., 2001, 2005) and Algeria(Djemila, ancient Cuicul; new data included in this work). On thebasis of fieldworks and archaeological studies Peacock (1980,1986) concluded that the main quarry and production centre ofleucite-bearing Roman millstones was located close to Orvieto(between Sugano and Buonviaggio; Fig. 2) in the Vulsini VolcanicDistrict (0.6e0.125 Ma; Nappi et al., 1998; Peccerillo, 2005). Thefirst detailed petrographic and geochemical database on thisquarry with a clear archaeometric goal was created by Antonelliet al. (2000, 2001). The data confirmed Peacock's suggestion andrevealed the local use of this rock for some oval saddle-quernsalready in the ninth century BC. Later on, several petro-archaeo-metric works (Renzulli et al., 2002a; Buffone et al., 2003; Santiet al., 2004; Antonelli et al., 2005) showed unequivocally thatthe leucite phonolite quarried near Orvieto is the most widelyused lava for manufacturing millstones in the Roman period. It

was also inferred (Antonelli et al., 2001) that at ca 10 km ESE ofthe Orvieto quarries, at the confluence of the Tiber and PagliaRivers, the fluvial port of Pagliano was the main collecting pointfor the millstone trade (they were probably shipped as ballast withwheat loads) along the River Tiber. This latter was a natural fluvialwaterway which enabled the Orvieto artefacts to be transporteddown to the Tyrrhenian Sea (Pavolini, 1986; Antonelli et al., 2001;Renzulli et al., 2002a). Similarly, the port of Ostia Antica, located atthe estuary of the River Tiber, probably represented the startingpoint of the leucite phonolite millstones for their journeys alongthe different Mediterranean routes.1 The strategic position of thequarries and the high grinding performance of these rotarymillstones (due to the high vesiculation and intrinsic abrasivecapacity of the mineralogical assemblage of the rock as well as toits durability) only partially explains why they were so frequentlyexported to faraway provinces of the Roman Empire, also to placeswhere fairly similar lavas outcrop and were used to produce thesame items most likely cheaply because of lower transportationcosts (i.e. Pompeii). Probably, apart from commercial reasons, thisimportant trade involving the pistrina of all the western Medi-terranean (Fig. 3a) depended on historical and symbolic aspectsrelated to the renown of the place where this kind of millstonewas invented.

2.3. Leucite basaltic trachyandesites from Castello di Cisternaquarry e Somma-Vesuvius Complex

The leucite-bearing lavas from the Somma-Vesuvius, specifi-cally those outcropping and exploited close to Castello di Cisterna(Naples; Fig. 2), were indicated as the probable rock used for thehourglass millstones of ancient Pompeii from the end of thenineteenth century (Tenore, 1883). One century later, Peacock(1980, 1989), basing his opinions both on hand specimens andtypological comparison with volcanic millstones from Orvietofound at Ostia, was the first to suggest that only a part of thosediscovered at Pompeii were made from the Vesuvius raw mate-rials. More recently, Buffone et al. (2000, 2003), in the firstdetailed archaeometric studies of this topic, stated that more than60% of the Pompeiian hourglass millstones were produced atOrvieto (infra) while fewer than 40% are made of local leucitebasaltic trachyandesites belonging to the oldest eruptions ofSomma-Vesuvius (30 ka ago; Peccerillo, 2005; these products arealmost wholly covered by the younger volcanic formations) andcropping out at Castello di Cisterna (near the Circumvesuviusrailway station) and outside the walls of Pompeii, east of theAmphitheatre. They also pointed out that these volcanic rockscorrespond to the so-called ottavianiti of Johansen (1937), a namenowadays no longer used. Working from the suggestion of �Sebesta(1974) on the presence at Aquileia of Somma-Vesuvius rock mill-stones, Buffone et al. (2003), on the basis of a morphologicalexamination of the mills conducted simply on the picturesannexed to the �Sebesta paper, stated both that Vesuvius must havebeen an export area for millstones and that there must have beena trade route for these items from Naples to Aquileia (UD e Friuli).We are currently carrying out a detailed petrographic andgeochemical study on the Aquileia millstones. However, there is sofar no significant archaeological-archaeometric evidence tosupport this conclusion or to suppose the existence of trade ona large or medium scale. In fact, hourglass millstones from thisregion have been found only in Campania and at Grumentum(Basilicata; Lorenzoni et al., 2000a,b).

1 We underline that all the rotary-millstones present in the big bakery of OstiaAntica come from Orvieto (Santi et al., 2004).

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e20922084

Author's personal copy

2.4. Tephrites-foidites from Vulture (Potenza e Basilicata)

The Mount Vulture is an extinct volcano, mid-Pleistocene in age(De Fino et al., 1986), rising on the southern Apennine Chain(northern Basilicata; Fig. 2) and representing the easternmostmagmatic event occurring during the Quaternary in central-southern Italy. It was an active millstone producing area from the

Bronze Age to Roman times and beyond, but use and export of theseitems were just regional (Lorenzoni et al., 1996, 2000a,b). Romanmillstones made of tephrite-foiditic lavas from Vulture have beendetected in a few Roman sites of the southern Italian mainland, e.g.,Basilicata, Molise and Apulia regions (i.e., Egnatia, S. Giovanni diRuoti, Biferno Valley, Cannae, Altamura Gravina di Puglia; Volterraand Hancock, 1994; Lorenzoni et al., 2000a,b; Williams-Thorpe,1988; Volterra, 1997). They are only of the Olynthian hopper-rubber type and, following Lorenzoni et al. (1996), were manufac-tured in several (unknown) localities scattered on the outcroppingarea of the small flows of the vesicular lavas, particularly on thenorth-eastern and south-eastern slopes of the volcano. The sameauthors found excavation signs on tephrite blocks between thevillages of Melfi and Rapolla.

2.5. Rhyolitic ignimbrite from Mulargia (Sardinia)

Sardinia was an important millstone production centre anda source of millstone trade during the period of Roman settlement.Studies of Roman millstones on the island showed that thePompeiian type is the most common, whereas cylindrical handquerns occur more rarely (Peacock, 1980; Williams-Thorpe andThorpe, 1989). The great majority of these items are made ofa distinctive reddish rhyolitic ignimbrite and, to a very minorextent, of grey vesicular lavas of basic-intermediate composition.Following Williams-Thorpe and Thorpe (1989), there are severalareas on the island where archaeological, historical and localtradition indicate a possible millstone production in the past. Inparticular, the rhyolitic millstones are from a single source ofOligocene-Miocene ignimbrite cropping out at Mulargia (calledMolaria in Roman times; Meloni, 1975), a village near Macomer(west-central Sardinia; Fig. 2), while the millstones made of inter-mediate-basic lavas have varied sources within Tertiary and, aboveall, PlioceneePleistocene volcanics, i.e.: Monte Arci (west Sardinia),ca 30 km south of Oristano; Monte Teccu, in the south-easternsectors of the island; Montiferro and Punte Luzzanas (west-centralSardinia), southwest of Macomer; Orroli and Nurri (southernSardinia), ca 50 km north of Cagliari and some others. However, onthe basis of the archaeometric studies (Peacock, 1980; Williams-Thorpe, 1988; Williams-Thorpe and Thorpe, 1989) we canconclude that, starting from the 1st century AD, only the Mulargiamillstone production area is clearly proven as a major source andshows clear evidence of significant Roman trade, whereasmillstones from all the other Sardinian localities (e.g., the sub-alkaline basalts from Monte Arci) were merely exploited locally orregionally during the Roman period. Mulargia millstones, almostexclusively hourglass-shaped, were widely exported in the westernMediterranean (particularly towards North-Africa) from Morocco(Volubilis e unpublished data e and Tetouan; Williams-Thorpe,1988; Williams-Thorpe and Thorpe, 1989) to Sicily (Segesta,Solunto, Selinunte and Megara Iblea) passing through Spain(Ampurias and Mallorca), Algeria (Djemila e unpublished data),and Tunisia (Utica, Carthage, Musti, Sousse and Gightis; Williams-Thorpe and Thorpe, 1989). Peacock (1980) first supposed a tradein millstones between Sardinia and North Africa from the Roman toByzantine periods remembering also that the island was under thecontrol of Carthage during the Vandal period. This trade (partiallyand indirectly confirmed also by the presence of columns made ofSardinian pink granite in many of the above-mentioned sites)generally shows a steep fall in the frequency of occurrences as thedistance from Sardinia increases (Williams-Thorpe and Thorpe,1989); since this assumption does not appear to apply toCarthage, where a significant number of Pompeiian millstonesmade of Sardinian red-brown ignimbrite were found, Williams-Thorpe (1988) suggested that the town had a role as importer

Fig. 3. (a) Geographic distribution of leucite phonolitemillstones fromOrvieto, inferredthrough detailed petrological studies (full circles) or hand specimens/quick petrography(asterisks). The Orvieto production centre (here located as a stylized rotary millstone)and the River Tiber (bold line in central Italy) are also located. 1. Cyrene and 2. LeptisMagna (Libya; Antonelli et al., 2005); 3. Sabratha (Libya; Antonelli, unpublished data); 4.El Djem and 5. Carthage (Tunisia, Peacock, 1980); 6. Cuicul (Djemila, Algeria; presentstudy); 7. Palermo (Williams-Thorpe, 1988); 8. Halaesa (Peacock, 1980); 9. Grumentum(Lorenzoni et al., 2000b); 10. Paestum (Peacock,1980,1989); 11. Pompeii (Peacock,1989;Buffone et al., 2003); 12. Herculaneum (Peacock, 1980, 1989); 13. Mondragone(Williams-Thorpe, 1988); 14. Biferno Valley (Williams-Thorpe and Peacock, 1995); 15.Ostia (Santi et al., 2004); 16. Anguillara (Peacock, 1986); 17. Veii (Peacock, 1980); 18.Suasa (Santi et al., 2004); 19. Fossombrone (Renzulli et al., 2002a); 20. S.Angelo in Vado(Antonelli et al., 2001); 21. Colombarone (Santi et al., 2004); 22.Pesaro (Antonelli et al.,2001); 23. Lucca (Peacock,1989); 24. Luni (Peacock,1980); 25. Cannetolo di Fontanellato(Santi et al., 2004); 26. Concordia (Donner, 1993); 27. Aquileia (unpublished data; workin progress); 28. Magdalensberg, Klagenfurt (Carinthia; T. Gluhak, personal communi-cation); 29. Carnuntum / Bad Deutsch-Altenburg (Austria; T. Gluhak, p.c.); 30. LesMartys (Oliva et al., 1999); 31. Empuries; 32-35. Badalona, Barcelona, Carthagena, Zar-agoza (Gimeno et al., 2010); 36. Astorga (Peacock, 1986, 1989); 37e38. Nea-Pafos &Nicosia, Cyprus island (Antonelli, quick petrography) (b) Geographic distribution ofSardinian ignimbrite millstones from Mulargia (here located as a stylized rotary mill-stone) in the Western Mediterranean area. After Williams-Thorpe and Thorpe, 1989,modified. 1. Ampurias; 2. Tetouan musum; 3. Pollentia (Mallorca; Williams-Thorpe andThorpe, 1991) 4e10. Sassari; San Pietro di Sorres; Sant'Elena; Monte Zuighe; Sa Pattada;Mulargia; Tharros; 11. Segesta; 12. Solunto; 13. Megara Hyblea; 14. Selinunte; 15. Utica;16. Carthage; 17. Musti; 18. Sousse Museum; 19. Gightis; 20. Cuicul (Djemila, Algeria;Antonelli and Lazzarini, quick petrography); 21. Volubilis (Morocco; Antonelli andLazzarini, quick petrography).

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 2085

Author's personal copy

and secondary distributor of Mulargia millstones in north Africa.The fact that Mulargia millstones (like those from Orvieto) wereexported to parts of the Mediterranean where local lavas werepresent and used is an indication of their good reputation (Fig. 3b).

2.6. Hawaiites and mugearites from Mongibello e Etna (and basaltsfrom Pantelleria)

As recognized by Williams-Thorpe (1988), Etnean hawaiites,mugearites and, to very minor extent, basalts were widely employedin the production of millstones in antiquity (locally begun in theBronze Age; Ferla et al., 1984). We can assume e as also revealed bythe finds of grinding tools dating back to the sixth century BC both inthe Apulia region (Lorenzoni et al., 2000a,b) and Istria and Italian-Slovenian Karst (Antonelli et al., 2004)e that their tradewas alreadywell organized during protohistory. Old and recent studies(Williams-Thorpe, 1988; Volterra and Hancock, 1994; Lorenzoniet al., 1996; Buffone et al., 2000, 2003; Renzulli et al., 2002a;Antonelli et al., 2005) documented the presence of Roman mill-stones made of these rocks not only within Sicily but also in central-southern Italy (Marche, Apulia and Campania regions), Spain(Ampurias), Tunisia (i.e., Carthage, Thuburbo Maius, Utica, ElMaklouba, Thapsus), Tripolitania and Cyrenaica (Lybia). Williams-Thorpe (1988) noted the presence in North Africa (Tunisia) of arte-facts both fromMt. Etna and the Sicilian Na-alkaline volcanic islandstraditionally considered as the historical sources of basaltic s.l. mill-stones (i.e. Pantelleria and, to a very minor extent, Ustica) butunfortunately the paper does not present the complete chemicaldata for all of the numerous millstones considered. Antonelli et al.(2005) clearly identified Roman millstones manufactured withPantellerian basalt and Etnean mugearite in the provinces of Tripo-litania (at Leptis Magna) and Cyrenaica (at Cyrene) which are amongthe southernmost production areas of grain in the Roman Empire.Sicily and the adjacent small islands provided both obvious stop-over sites and important millstone sources on the traditional north-south axis of the wheat trade (as mentioned by Strabo, VI.2.3: Etna).All the above-mentioned research papers indicate the Mongibellostratovolcano lava flows as the source of the Etnean raw materialexploited by Romans (Fig. 2). More specifically, it was ascertainedthat the most widely worked rocks were mugearites and hawaiitesbelonging to theMongibello Recente activity (Cristofolini et al., 1991),dating from 14 ka to the present (Peccerillo, 2005). Williams-Thorpe(1988) first and Renzulli et al. (2002a) later suggested that the FratelliPii quarry (on the outskirts of Catania and dating from 693 BC) wasanother of the Roman sites regularly exploited to work hawaiiticmillstones. Following Buffone et al. (2003), who detected fourEtnean rotary-millstones at Pompeii, an additional possible Romansite for the production of mugearitic millstonesmay be foundwithinthe outcropping area of the Pizzi Deneri formation (Older Mon-gibello; Coltelli et al., 1994).

3. Useful petrographic and geochemical markers forarchaeometric purposes

Petrographic and geochemical features here summarised havebeen generally taken from the recent literature considering at leastsix samples (more often ten or tens) for each kind of lava. To avoidanalytical bias, most of chemical data considered refer to the XRFanalytical method for major and trace elements. In the case of theleucite-bearing lavas from the Orvieto region we used the currentdatabase which was produced by ICP-OES-MS methods (Antonelliet al., 2001). Anyway, a comparison between these data and thoseproduced through XRF on few samples of the same rock-type(Buffone et al., 2000) proved a satisfactory analytical compatibilityfor the most discriminant elements.

3.1. Euganean trachytes from the Venetian VolcanicProvince e They are mildly vesicular and of a colour that variesthrough the different shades of grey

According to the usual TAS classification diagram (Fig. 5a) theserocks are principally transitional trachytes, seldom rhyolites ortrachyandesites. Capedri et al. (2000) outlined mineralogical-petrographic, and chemical parameters characterising the trachytesof the most important historical quarries of the district. Froma compositional and textural point of view Euganean trachytes arealways porphyritic lavas (PI mainly from 20vol.% to 40vol.%),frequently not seriate and with glomerophyre aggregates. Anor-thoclase (�Na-sanidine)> plagioclase> biotite�Mg-kaersutiticamphibole� clinopyroxene are the main phases as phenocrysts(Fig. 4d); titano-magnetite, apatite and zircon are ubiquitousaccessory minerals, whereas titanite only crystallises in a fewtrachytes (Monselice, Monte Merlo, Monte Trevisan). Phenocrystsof allotriomorphic to euhedral anorthoclase, with crystals varyingfrom 2 to 10 mm in size, frequently show evidence of internalmelting (spongy texture) and very thin rims of new anorthoclaseovergrowths. Euhedral to subhedral plagioclase phenocrysts areoften zoned and may also be rimmed by anorthoclase or Na-sani-dine. Biotite and, when it occurs (Monselice, Monte Merlo and notmany others), amphibole are frequently oxidised and embayed-re-absorbed. Fabrics are characterised by a holo-microcrystallinegroundmass containing feldspar microlites (mainly of anortho-clase) which sometimes show sub-parallel orientation due tomagmatic flow (pilotaxitic/trachytic textures; e.g. lavas from theMonselice andMonte Oliveto areas) as well as no fluidal orientation(felty texture; e.g. trachytes fromMonte Cero, Monte Altore, MonteRosso, Monte Merlo, Monte Lispida and many other areas; Capedriet al., 2000); small amounts of interstitial quartz and, occasionally,minute interstitial brownish glass may also be present in thegroundmass. It is very common to see grey-black inclusions withporphyric/granitoid/very weakly schistous fabric normally refer-ring to trachyandesitic, gabbroic and cornubianitic composition,respectively (Lazzarini et al., 2008 and reference therein), thatcontain a larger amount of biotite, amphibole, pyroxene andmagnetite than ordinary trachyte, and sometimes small amounts ofcalcite; more rare are white-gray xenoliths of alkaline-rhyolites orgranitoid rocks.

With regard to the chemical composition, general commonfeatures are K2O/Na2O ratio around 1, the absence of Nb-Ta negativeanomalies and the presence of Q and Hy in the CIPW norm (Milaniet al., 1999). As described by Capedri et al. (2000), trachytes ofindividual quarrying areas are chemically quite homogeneous, butthere is a rather wide chemical variability among the different sites,which allows a good differentiation within the main Roman sour-ces. The authors consider TiO2, Zr, Th, Nb, Y, V, Rb, Sr and Pbparticularly useful for discriminating and propose some valuablebinary plots able to reduce all the main quarried trachytes to fivefields (Th vs Sr; Fig. 8a) and to separate the stone varietiesbelonging to the fourth and fifth field groups (i.e., TiO2, Rb and Zr vsK2O; Y vs Nb and V; TiO2 vs Th and Zr; Fig. 8b).

3.2. Leucite phonolite from Orvieto

From a petrographic point of view these rocks can be describedas grey to light-grey vesicular (vesicules around 10e15vol.%) leucite-bearing lavas, characterised by large euhedral leucite phenocrysts(mainly 8e18 mm in size) which show complex zoning andfrequent inclusions of pyroxene� plagioclase� opaque minerals.Among the most common micro- and phenocrysts (PorphyriticIndex 25e30vol.%) are also green clinopyroxene (Fig. 4a), sanidine,plagioclase (as strongly zoned single crystals, or as aggregates), at

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e20922086

Author's personal copy

times rimmed by sanidine, and FeeTi oxides. The microcrystallinepilotassitic to intergranular groundmass consists of sanidine,leucite and plagioclase microlites with subordinate clinopyroxeneand ore minerals (Fig. 4a). As regards geochemistry, these lavas areevolved members, strongly undersaturated in silica, belonging tothe Roman-type high potassium series (HKS; Peccerillo, 2005;average K2O/Na2O> 2.5) of the Roman Magmatic Province(Appleton, 1972). According to the modal mineralogy and TotalAlkali-Silica classification diagram (TAS; Le Maitre et al., 1989), theyare essentially phonolites (Fig. 5a). More specifically, they showappreciable enrichment in light rare earths (LREE), La, Sr, Th and,Ba, together with Nb and Ti negative anomalies, which are alltypical features of the subduction-related Quaternary potassicrocks from the north-west sector of the Roman Volcanic Province(Serri, 1990). As verified first by Antonelli et al. (2000, 2001), in thecase of the rocks from the Orvieto quarries, their highest abundanceof La (172e228 ppm), Sr (1823e2167 ppm), Th (136e178 ppm) andBa (1957e2340 ppm) are very useful chemical fingerprints fordifferentiating these leucite phonolites from the other similar rocks

outcropping within the Roman Volcanic Province. La, Th, Sr versusBa binary diagrams proved to be the most efficient for this purpose(Antonelli et al., 2000, 2001; Renzulli et al., 2002a; Santi et al.,2004; Fig. 6a). The possible overlapping of the Vulture andOrvieto fields in the diagram Ba vs Sr can be easily resolved throughthe petrography (discriminant presence of haüyne in the lavas fromVulture; infra).

Similar petrographic (Fig. 4b) and geochemical (Figs. 5 and 6a)features have been found for two catillus (#D¼ h: 42 cm, internalØ: 25 cm; #D3¼ h: 37 cm, internal Ø: 24 cm) and one meta(#D4¼ h: 30 cm, maximum Ø: 25 cm) discovered in the ancientCuicul (Algeria). Results of the petrochemical study conducted onthem are summarised in Figs. 4e6 and Table 1.

3.3. Somma-Vesuvius leucite basaltic trachyandesites from Castellodi Cisterna

They are highly porphyritic lavas (PI ca 50e65vol.%); augiticeuhedral clinopyroxene (mainly 3 mm in size; Ømax� 5 mm),

Fig. 4. Photomicrograph of a thin section of a sample of a: (A) leucite phonolite from the Orvieto Roman quarry: leucite (lct) and clinopyroxene (cpx) phenocrysts in a micro-crystalline-pilotassitic groundmass (gdm) which is mainly feldspathic� leucite�Mg-Fe minerals; (B) leucite phonolite used for the catillus D3 found in Djemila; (C) Etneanmugearite showing plagioclase, clinopyroxene� olivine (ol) phenocrysts in a microcrystalline-intergranular groundmass; (D) Euganean trachyte from the Roman site of MonteRosso: anorthose (anr), plagioclase (pl), biotite (bt) and clinopyroxene (cpx) phenocrysts in a microcrystalline groundmass; (E) Vesuvian basaltic trachyandesite from the Castello diCisterna area, showing augite (cpx), plagioclase � olivine and leucite phenocrysts and aggregates embedded in a microcrystalline groundmass mainly made of feldspar, pyroxeneand FeeTi oxides; (F) tephrite from the Vulture Volcano: haüyne (hyn) and clinopyroxene phenocrysts in a fine-grained groundmass. Crossed polarized light; long side of thepictures is 2.5 mm except for (F) for which is 5 mm.

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 2087

Author's personal copy

idiomorphic leucite (Ømax 4e5 mm), labradoritic-bytowniticplagioclase (Ømax 2 mm) and olivine (Ømax 1.5 mm) are the mostabundant phenocrysts respectively (Fig. 4e); occasionally raresanidine may also be present. Pyroxene, leucite and plagioclasemay each form polycrystalline aggregates. The microcrystallinegroundmass consists (in decreasing order of abundance) of feld-spar, pyroxene, leucite, FeeTi oxides, phlogopite and apatite.

In the TAS diagram (Le Maitre et al., 1989; Fig. 5a) they fallessentially in the basaltic trachyandesites field, seldom in that of

the phonolitic tephrites. These rocks, as always for the potassicseries (KS; Peccerillo, 2005) of the Roman Magmatic Province, arecharacterised by K2O/Na2O ratios varying from 1.5 to 2.5(often< 1.8; Joron et al., 1987), absence of Ba and P negativeanomalies (Serri, 1990), La 43e48 ppm, Sr 673e696 ppm and Ba1449e1502 ppm (Buffone et al., 2000, 2003). Their mineralogicaland chemical compositions suggest to classify they as shoshonitesand allow these leucite-bearing lavas to be readily differentiatedfrom the others outcropping within the Roman Volcanic Province(Fig. 6a).

3.4. Tephrites-foidites from Vulture (Potenza, Basilicata)

Unlike the volcanic complexes aligned from Vulsini to Vesuviusalong the Tyrrhenian margin of Italy, Mount Vulture is located nearthe easternmost border of the Appennine compressive front. Thispeculiar structural setting is accompanied by a unique compositionof magmas and derived alkaline rocks, which are characterised byboth K and Na enrichment (Beccaluva et al., 2002) as well as bycommon presence of haüyne in all the volcanic products (De Finoet al., 1986; Beccaluva et al., 2002; Peccerillo, 2005).

Tephrite-foidite vesicular lavas (vesicles ca 35vol%) used formillstones show evident porphiritic texture (PI ca 30e35vol%) andare composed of phenocrysts mainly of green pyroxene andhaüyne>> leucite and nepheline� biotite and apatite (Fig. 4f).They are embedded in a very fine-grained groundmass in whichopaque minerals, plagioclase, pyroxene, feldspathoids and occa-sionally K-fedspar may be recognizable. Pyroxene phenocrysts,generally abundant and zoned, have fairly irregular form andinclusions of haüyne, opaques and nepheline. Those of haüyne arecommon or abundant and usually appear smaller and morerounded than pyroxene. Their colour is typically blue at the rim.Finally nepheline, leucite and biotite (which may be altered)phenocrysts are commonly small in size. Using the TAS diagram(Fig. 5a) these lavas fall in the tephrite, tephrifonolite and foiditefields in agreement with the petrographic classification (De Finoet al., 1986; Caggianelli et al., 1990; Beccaluva et al., 2002;De Astis et al., 2006). Geochemistry reveals that they belong tothe potassic alkaline series (De Fino et al., 1982, 1986) of the RomanMagmatic Province, with K2O/Na2O variable, but frequently high(always> 1) although haüyne is the dominant feldspathoid(Lorenzoni et al., 2000a). In these basic lavas the K/Na ratio issimilar to those of KS basic magmas (Fig. 5b), but the enrichment ofmost incompatible elements and the degree of silica under-saturation are close to those of HKS magmas (De Fino et al., 1986).CaO and TiO2 vol% are mainly 8.1e12.4 and 0.8e1.4, respectively,while, with regard to trace elements, the Zr values are generallybetween 305 and 570 ppm, V varies roughly from 180 to 270 ppm,Sr approximately from1600 to 2850 ppm, Rb from 70 to 170 ppm,Ba from 1700 to 2800 ppm and Y roughly from 40 to 60 ppm(De Fino et al., 1986; Lorenzoni et al., 2000a; Beccaluva et al., 2002;De Astis et al., 2006). In the Mediterranean basin as a whole thesemineralogical and geochemical compositions (cfr. Figs. 6a and 7)are peculiar just to Mt. Vulture, the only volcano to have suchabundant haüyne in the emitted products (among all the volcanoesof the Roman Magmatic Province negligible amounts of haüyne arepresent only in the Roccamonfina lavas) (Lorenzoni et al., 2000a).

3.5. Rhyolitic ignimbrite from Mulargia (Sardinia)

This ignimbrite has a distinctive red colour with paler fiammeand contains many sharp edged vesicles (usually about 1e3 mm insize), very often lined with a typical green mineral, supposed to beceladonite (Williams-Thorpe and Thorpe, 1989) probably mixedwith some kind of zeolite. In thin-section it exhibits a brown-red

Fig. 5. (a) The alkali-silica classification (TAS) of both the six Italian volcanic millstonesource rocks object of this paper and the analyzed leucite-bearing volcanic millstonesfrom Cuicul (Algeria: full triangles). Diagram (after Le Maitre et al., 1989) includes thesubdivision of volcanic rocks into alkaline and subalkaline. The boundaries are asfollows: � ¼ Kuno, 1966; <¼ Irvine and Baragar, 1971. Abbreviations: H: hawaiites; M:mugearites; TA: trachyandesites; T: trachytes; PB: picro-basalts; B: basalts; BA: basalticandesites; BT: basaltic trachyandesites; A: andesites; D: dacites; Te-Bs: tephrites andbasanites; PhTe: phono-tephrites; TePh: tephri-phonolites; Ph: phonolites; F: foidites;R: rhyolites. (b) Na2O vs. K2O variation diagram for both the principal Italian volcanicraw material sources and the analyzed leucite-bearing volcanic millstones from Cuicul(full triangles). Fields marked with gray broken lines refer to the three main leucite-bearing lava sources (Orvieto, Vesuvius, Vulture). Data referring to basic lavas fromPantelleria, Ustica and Hyblean Plateau are plotted for comparison with Etnean lavas.Separation among HK, K and Na series classically adopted for alkaline basic rocks (afterMiddlemost, 1975), is plotted too (grey dashed lines) to show the Na-affinity of all theSicialian lavas. Data for comparison are from: Antonelli et al., 2001 and Buffone et al.,2000 (open triangles: leucite-bearing lavas from the Roman quarries of Orvieto, VulsiniVolcanic Discrict); Cristofolini et al., 1991 (circles: hawaiites and mugearites from theMt. Etna, Mongibello Recente); Buffone et al., 2000 (squares: leucite basaltic tra-chyandesites from Castello di Cisterna, Somma-Vesuvius); De Fino et al., 1986;Williams-Thorpe, 1988 and Beccaluva et al., 2002 (crosses: tephrites-foidites fromVulture Volcano; Capedri et al., 2000 (open diamonds: trachytic lavas from EuganeanHills); Williams-Thorpe, 1988 and Williams-Thorpe and Thorpe, 1989 (asterisks:rhyolitic ignimbrite from Mulargia); Civetta et al., 1984, 1998 (rotated crosses: alkalineand transitional basalts from the island of Pantelleria); Trua et al., 1998 (full grayasterisks: alkaline basalts from the Hyblean Plateau); Trua et al., 2003 (crossedsquares: basic lavas of Ustica). Separation among HK, K and Na series classicallyadopted for alkaline basic rocks (after Middlemost, 1975), is plotted too (grey dashedlines) to show the Na-affinity of the Sicialian lavas.

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e20922088

Author's personal copy

glassy (often devitrified glass) groundmass, showing traces of flowstructure (Peacock, 1980), embedding very rare phenocrysts ofquartz and andesine feldspar� biotite � opx. This rock outcrops inthe north-west of the Sardinia and belongs to the relatively high Kcalc-alkaline dacite-rhyolite lava series erupted during theOligoceneeMiocene (30e13 ka) subduction of lithospheric plate inthe SardinianeCorsican microplate environment, so it showschemical characteristics common to island-arc related rocks(Dostal et al., 1982; Peccerillo, 2005). Following data reported byWilliams-Thorpe (1988) and Williams-Thorpe and Thorpe (1989)the Mulargia ignimbrite exhibits low concentrations of Cr(ca 2e20 ppm); Rb ca 140e165 ppm; Sr ca 150e190 ppm, Y ca30e53 ppm; V ca 20e43 ppm; Zr ca 200e230 ppm, TiO2 around0.60%, SiO2 ca 67e69; Al2O3 ca 14.9e16%; K2O/Na2O ratio roughly 1(frequently slightly< 1) and K2OþNa2O� 8%. Obviously, to proveunivocally a provenance from Mulargia, petrochemical analysesshould be always necessary for a scientific validation of the origin ofthis high-silica rock (Figs. 6a and 7). Unfortunately, due to itsgeneral macroscopic aspect, supposed to be sufficiently distinctiveto identify it in hand specimens directlywith the naked eye bymost

of the archaeologists, archaeometric analyses concerning this kindof volcanic millstones are very rare (few analyzed samples arereported just in Williams-Thorpe, 1988 and Williams-Thorpe andThorpe, 1989).

3.6. Etnean hawaiites and mugearites from Mongibello(and basalts from Pantelleria)

Mugearites and hawaiites are generally grey to dark-greyslightly vesicular (vesicles� 10%) seriate lavas often characterisedby evident porphyritic texture (PI: 20e60 vol.% ca for mugearites;30e50 vol.% ca for hawaiites). Mugearites have microcrystalline-intergranular groundmass made up of plagioclase, opaqueminerals and less abundant pale-green or colourless clinopyrox-ene. Phenocrysts and microphenocrysts are represented by pla-gioclase>> clinopyroxene> olivine> FeeTi oxides (Fig. 4c).Euhedral (labradoritic)-bytownitic plagioclases are the largestones (4e5 mm in size) and often feature spongy texture, deepembayments, glass and opaque inclusions. Augitic pale-greenpyroxene is normally small in size (mainly 0.5 mm, sometimes up

Fig. 6. (a) Sr vs. Ba discrimination diagram for the most important basic to intermediate Italian lavas; data are compared with those obtained for the leucite-bearing volcanicmillstones discovered in Cuicul (full triangles). Grey fields refer to Vulsini Volcanic District. (b) Sr vs. TiO2 discrimination diagram for the most exploited Italian basic lavas. Data forcomparisons are from: Villari, 1974; Civetta et al., 1984; Williams-Thorpe, 1988; Esperanca and Crisi, 1995; Civetta et al., 1998 (rotated crosses: alkaline and transitional basalts fromthe island of Pantelleria); Romano and Villari, 1973; Trua et al., 1998 (full gray asterisks: alkaline basalts from the Hyblean Plateau); Cinque et al., 1988; Williams-Thorpe, 1988; Truaet al., 2003 (crossed squares: basic lavas of Ustica); Antonelli et al., 2000, 2001 (open triangles: leucite-bearing lavas from the Roman quarries of Orvieto, Vulsini Volcanic Discrict);Conticelli et al., 1997 (long dashes: leucite-bearing lavas from the Sabatini Volcanic Complex); Antonelli et al., 2001 (short dashes: leucite-bearing lavas from the Vico Volcano); DeFino et al., 1986 and Beccaluva et al., 2002 (crosses: tephrites-foidites from Vulture Volcano); Buffone et al., 2000 (basaltic trachyandesites from Castello di Cisterna, Somma-Vesuvius; open squares: quarry samples; full squares: millstones); Cristofolini et al., 1991 (open circles: hawaiites and mugearites from Mt. Etna, Mongibello Recente); Tanguy et al.,1997 (full circles: tholeiitic basalts from Mt. Etna Volcano).

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 2089

Author's personal copy

to 3.5 mm), whereas olivine phenocrysts are smaller (main-ly� 0.5 mm in size) and show a rounded habit.

Hawaiitic lavas have microcrystalline-intergranular groundmasscomposed of plagioclase, clinopyroxene, olivine and FeeTi oxides.They include pheno- and microphenocrysts of euhedral sievedplagioclase (up to 3 mm in size, with opaque and glass inclusions)>augitic green to brownish pyroxene (up to 2 mm in size andincluding oxides)� sub-rounded olivine (around 1 mm in size; onoccasion in glomerophyric associations with clinopyroxene).

As concerns the geochemical characters of mugearite, hawaiitesfrom Mongibello Recente, they refer to original magmas related toan extensional within-plate regime and with a weak Na-alkalineaffinity; This is shown, for example, by the Th/Nb (see, e.g., Fig. 8 ofBeccaluva et al., 1991) and K2O/Na2O ratios (¼0.5; Peccerillo, 2005).In particular, useful fingerprints are represented by TiO2< 2 wt. %,high Sr values (>1000 ppm) and Ba (>700 ppm) (Cristofolini andRomano, 1982; Cristofolini et al., 1991; Peccerillo, 2005). Further-more, Sr vs Ba (Fig. 6a), Nd, Sr vs TiO2 (Antonelli et al., 2004, 2005;Fig. 6b) or Zr vs V (Fig. 7; after Williams-Thorpe, 1988, modified)diagrams can be quite valuable for discrimination between ourbasic lavas and those from other Etnean areas (tholeiitic basalts),Hyblean Plateau (alkaline and transitional basalts), Ustica (alkali-basalts, hawaiites and mugearites), and Pantelleria (alkaline andtransitional basalts); these are virtually all possible sources forRoman volcanic millstones. In particular, as reported by Williams-Thorpe and Thorpe (1990), Pantelleria was a producer of small,relatively simple millstones from at least the Bronze Age to theRoman period. Basaltic lavas outcropping as far as the coast in thenorthern (at San Leonardo and Mursia; Civetta et al., 1984) andnorth-east parts of the island (at Le Balate; Villari, 1974; Civettaet al., 1984) were the most probable flow sources. Specifically, thedark-grey vesicular, olivine-basalts of San Leonardo, which are

Fig. 7. Discrimination among the six main Italian millstone source rocks considered inthis paper using Zr and V (after Williams-Thorpe, 1988, modified). For comparison withEtnean lavas, data referring to other basic Sicilian rocks are plotted too. The graybroken line separates the acid from the basic-to-intermediate rocks. Data are from:Williams-Thorpe, 1988; Trua et al., 2003; Peccerillo, 2005, for Pantelleria, HybleanPlateau and Ustica; Antonelli et al., 2001 and Buffone et al., 2000, for Orvieto region;Capedri et al., 2000, for Euganean Hills; Cristofolini et al., 1991, for Etnean “Mongibellorecente” lavas; Williams-Thorpe, 1988 and Beccaluva et al., 2002, for Mt. Vulture;Williams-Thorpe, 1988 and Williams-Thorpe and Thorpe, 1989, for Mulargia. Symbolsare as in Figs. 5 and 6. Full triangles are the analyzed millstones from Cuicul. Small palegrey circles refer to Roman millstones analyzed by scholars cited in the text and to oneunpublished trachytic millstone from Aquileia.

Fig. 8. (a): Sr vs.Th diagram for the discrimination of quarried sites of the trachytes inthe Euganean Hills (fields and data from Capedri et al., 2000). Field 1: Monselice; Field2: Mt. Trevisan; Field 3: Mt. Altore, Mt. Pendice; Field 4:Mt. Oliveto, Mt. Bello, Mt. Cero,Mt. Lonzina, Mt. Lozzo, Mt. Merlo, Mt. Murale, Mt. Rosso; Field 5: Mt. Alto, Mt. Grande,Mt. Lispida, Mt. Oliveto2, Mt. Rusta, Mt. S.Daniele. (b): TiO2 vs. Zr diagram for thediscrimination of the Euganean trachytes falling in field 4 of Fig. 8a (fields and datafrom Capedri et al., 2000). Gray filled circles refer to three Roman mills from Antonelliet al., 2004 and one Roman millstone from Aquileia (unpublished data).

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e20922090

Author's personal copy

characterised by a seriate porphyritic texture (PI 25e30 vol. %;phenocrysts: labradoritic- bytownitic plagioclase> augitic clino-pyroxene> olivine), microcrystalline-intergranular groundmass(plagioclaseþ clinopyroxeneþ FeeTi oxides� olivine), chemicaltransitional/sodic affinity (K2O/Na2O ratio� 0.3, TiO2> 2 wt. % andSr< 550 ppm; Villari, 1974; Civetta et al., 1984, 1998), were the rawmaterial used to obtain some Roman millstones discovered inNorth Africa, specifically in Tunisia and Libya (Peacock, 1985;Williams-Thorpe, 1988; Antonelli et al., 2005).

As regards other possible Sicilian lava sources, the use of alkalineand transitional basalts from Ustica and Hyblaean Plateau, as wellas of andesites from the Aeolian island of Lipari is very rare outsidethe Sicilian district; very few Roman mills and grindstones made ofthese lavas have been identified on the Italian mainland(for example one possible grinding tool of Hyblean origin atFossombrone, Marches; Renzulli et al., 2002a) and in North Africa (aquern made of trachybasalt from Ustica is mentioned at Carthageby Williams-Thorpe, 1988).

4. Conclusions

The petrographic and geochemical features summarised above,when used together (possibly integrated by critical historical-archaeological data too) may produce reliable results concerningthe origin of the Italian raw material of the Roman volcanicmillstones. This approach enables most millstones to be attributedto a geological source, if not ever with absolute certainty thensurely with a fully acceptable degree of reliability. For three decadesat least, the petrochemical study of millstones (and all of thegeomaterials) has made substantial contributions to archaeologicalresearch into the reconstruction of ancient communication routes,trade networks and cultural links in different periods. Volcanicrocks outcrop in limited areas within the Mediterranean basin asa whole and Italian volcanics played a primary role in theproduction and trade in millstones during the Roman period. Thispaper brings together the petrography and major-trace elementsgeochemistry of themost exploited andwidespread Italian volcanicrocks worked as millstones during the Roman period as well asa general evaluation of the amount and geographical extent ofthe trade for millstones of each stone typology within theMediterranean.

References

Antonelli, F., Nappi, G., Lazzarini, L., 2000, Sulla “pietra da mole” della regione diOrvieto. Caratterizzazione petrografica e studio archeometrico di macinestoriche e protostoriche dall'Italia centrale. In: Proceedings of “I CongressoNazionale di Archeometria”, Verona, 1999, Patron Editore, pp. 195e207.

Antonelli, F., Nappi, G., Lazzarini, L., 2001. Roman millstones from Orvieto (Italy):petrographic and geochemical data for a new archaeometric contribution.Archaeometry 43 (2), 167e189.

Antonelli, F., Bernardini, F., Capedri, S., Lazzarini, L., Montagnari Kokelj, E., 2004.Archaeometric study of protohistoric grinding tools of volcanic rocks found inthe Karst (Italy- Slovenia) and Istria (Croatia). Archaeometry 46 (4), 537e552.

Antonelli, F., Lazzarini, L., Luni, M., 2005. Preliminary study on the import of lavicmillstones in Tripolitania and Cyrenaica (Libya). J. Cult. Herit. 6, 137e145.

Appleton, J.D., 1972. Petrogenesis of potassium-rich lavas from the RoccamonfinaVolcano, Roman Region, Italy. J. Petrol. 13, 425e456.

Beccaluva, L., Di Girolamo, P., Serri, G., 1991. Petrogenesis and tectonic setting of theRoman Volcanic Province, Italy. Lithos 26, 191e221.

Beccaluva, L., Coltorti, M., Di Girolamo, P., Melluso, L., Milani, L., Morra, V., Siena, F.,2002. Petrogenesis and evolution of Mt. Vulture alkaline volcanism (SouthernItaly). Mineral. Petrol. 74, 277e297.

Buffone, L., Lorenzoni, S., Pallara, M., Zanettin, E., 2000. Le macine rotative in roccevulcaniche di Pompei. Rivista di studi pompeiani 10, 117e130.

Buffone, L., Lorenzoni, S., Pallara, M., Zanettin, E., 2003. The millstones of AncientPompeii: a petro-archaeometric study. Eur. J. Mineral. 15, 207e215.

Caggianelli, A., De Fino, M., La Volpe, L., Piccarreta, G., 1990. Mineral chemistry ofMonte Vulture volcanics: petrological implications. Mineral. Petrol. 41, 215e227.

Capedri, S., Venturelli, G., Grandi, G., 2000. Euganean trachytes: discrimination onquarried sites by petrographic and chemical parameters and by magnetic

susceptibility and its bearing on the provenance of stones of ancient artefacts.J. Cult. Herit. 1, 341e364.

Cinque, A., Civetta, L., Orsi, G., Peccerillo, A., 1988. Geology and geochemistry of theisland of Ustica (Southern Tyrrhenian Sea). Rend. Soc, It. Mineral. Petrol. 43,987e1002.

Civetta, L., Cornette, Y., Crisci, G.M., Gillot, P.I., Orsi, G., Requiejo, C.S., 1984. Geology,geochronology and chemical evolution of the island of Pantelleria. Geol. Mag.121, 541e562.

Civetta, L., D'Antonio, M., Orsi, G., Tilton, G.R., 1998. The geochemistry of volcanicrocks from Pantelleria Island, Sicily Channel: petrogenesis and characteristics ofthe mantle source region. J. Petrol. 39, 1453e1491.

Coltelli, M., Garduño, V.H., Neri, M., Pasquarè, G., Pompilio, M., 1994. Geology of thenorthern wall of Valle del Bove, Mt Etna (Sicily). Acta Vulcanol. 5, 55e68.

Conticelli, S., Francalanci, L., Manetti, P., Cioni, R., Sbrana, A., 1997. Petrology andgeochemistry of the ultrapotassic rocks from the Sabatini Volcanic District,central Italy: the role of the evolutionary processes in the genesis of variablyenriched alkaline magmas. J. Volcanol. Geotherm. Res. 75, 107e136.

Cristofolini, R., Corsaro, R.A., Ferlito, C., 1991. Variazioni petrochimiche nellasuccessione etnea: un riesame in base a nuovi dati da campioni di superficie eda sondaggi. Acta Vulcanol. 1, 25e37.

Cristofolini, R., Romano, R., 1982. Petrological features of the Etnean vocanic rocks.Mem. Soc. Geol. It. 23, 99e115.

De Astis, G., Kempton, P.D., Peccerillo, A., Wu, T.W., 2006. Trace element and isotopicvariations from Mt. Vulture to Campanian volcanoes: constraints for slabdetachment and mantle inflow beneath southern Italy. Contribut. Mineral.Petrol. 151 (3), 331e351.

De Fino, M., La Volpe, L., Piccarreta, G., 1982. Magma evolution at Monte Vulture(southern Italy): inferences from mineral chemistry, major and trace elementdata. Contribut. Bull. Volcanol. 45, 115e126.

De Fino, M., La Volpe, L., Peccerillo, A., Piccarreta, G., Poli, G., 1986. Petrogenesis ofMonte Vulture volcano (Italy): inferences from mineral chemistry, major andtrace element data. Contribut. Mineral. Petrol. 92, 135e145.

De Pieri, R., Gregnanin, A., Sedea, R., 1983. Guida alla escursione sui Colli Euganei.Mem. Soc. Geol. Ital. 26, 371e381.

Donner, M., 1993. La macina per cereali nel Veneto di età Romana. In: “Nel nome delpane”, Ed. Regione Autonoma Trentino-Alto Adige, pp. 391e405.

Dostal, J., Coulon, C., Dupuy, C., 1982. Cainozoic andesitic rock of Sardinia (Italy). In:Thorpe, R.S. (Ed.), Andesites: orogenic andesites and related rocks. J. Wiley andSons, Chichester, pp. 353e370.

Esperança, S., Crisi, G.M., 1995. The Island of Pantelleria: a case for the developmentof DMM-HIMU isotopic compositions in a long-lived extensional setting. EarthPlanet Sci. Lett. 136, 167e182.

Ferla, P., Alaimo, R., Falsone, G., Spatafora, F., 1984. Studio petrografico delle macinedi età arcaica e classica da Monte Castellazzo di Poggioreale (Sicilia occi-dentale). Sicilia Archeol. 56, 25e52.

Irvine, T.N., Baragar, W.R.A., 1971. A guide to the chemical classification of thecommon volcanic rocks. Can. J. Earth Sci. 8, 523e548.

Gimeno, D., Aulinas, M., Fernandez-Turiel, J.L., Pugès, M., Novembre, D., 2010.Volume abstracts of “VI Congresso Nazionale di Archeometria - Scienza e BeniCulturali”, Pavia, 15–18 febrary 2010, 146.

Johansen, A., 1937. A Description Petrography of Igneous Rocks, vol. II. University ofChicago Press Ed., Chicago, pp. 1e428.

Joron, J.L., Metrich, N., Rosi, M., Santacroce, R., Sbrana, A., 1987, In «Somma-Vesuvius» (R. Santacroce Ed.), Chapter 3: Chemistry and Petrography, Quadernide «La Ricerca Scientifica», Progetto Finalizzato Geodinamica, CNR, Monografiefinali, 8, pp. 105e174.

Kuno, H., 1966. Lateral variation of basalt magmas types across continental marginsand island arcs. Bull. Volcanol. 29, 195e222.

Lazzarini, L., Antonelli, F., Cancelliere, S., Conventi, A., 2008. The deterioration ofEuganean trachyte in Venice. In: Lukaszewicz, Jadwiga W., Niemcewicz, Piotr(Eds.), Proceedings of the “11th International Congress on Deterioration andConservation of Stone”, Nicolaus Copernicus University, Torun Poland, 15e20September 2008, vol. 1, pp. 153e163.

Le Maitre, R.W., Bateman, P., Dudek, A., Keller, J., Lameyre, J., Le Bas, M.J., Sabine, P.A.,Schmid, R., Sorensen, H., Streckeisen, A., Woolley, A.R., Zanettin, B., 1989. In: LeMaitre, R.W. (Ed.), A classification of Igneous Rocks and Glossary of Terms,Recommendations of the International Union of Geological Sciences, Subcom-mission on the Systematics of Igneous Rocks. Blackwell Scientific Publications,p. 193.

Lorenzoni, S., Pallara, M., Venturo, D., Zanettin, E., 1996. Archaeometric preliminarystudy of volcanic rock millstones from Neolithic-Roman archaeological sites ofAltamura area (Apulia, Southern Italy). Sci. Technol. Cult. Herit. 5 (2), 47e55.

Lorenzoni, S., Pallara, M., Venturo, D., Zanettin, E., 2000a. Studio archeometricodelle macine in rocce vulcaniche della Puglia e zone limitrofe dall'età arcaicaall'età romana. Rassegna di archeologia 17.

Lorenzoni, S., Pallara, M., Venturo, D., Zanettin, E., 2000b. Volcanic rock Bronze Agemillstones of Apulia, Southern Italia: lithology and provenance. Eur. J. Mineral.12, 877e882.

Meloni, P., 1975. La Sardegna romana. Sassari, Ed. Chiarella. 270.Middlemost, E.A.K., 1975. The basalt clan. Earth Sci. Rev. 11, p. 337e364.Milani, L., Beccaluva, L., Coltorti, M., 1999. Petrogenesis and evolution of the

Euganean Magmatic Complex, Veneto Region, North-East Italy. Eur. J. Mineral.11, 379e399.

Moriz, L.A., 1958. Grain-mills and Flour in Classical Antiquity. Clarendon Press,Oxford. 230p.

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 2091

Author's personal copy

Nappi, G., Antonelli, F., Coltorti, M., Milani, L., Renzulli, A., Siena, F., 1998. Volca-nological and petrological evolution of the Eastern Vulsini District, Central Italy.J. Volcanol. Geotherm. Res. 87, 211e232.

Oliva, P., Beziat, D., Domergue, C., Jarrier, C., Martin, F., Pieraggi, B., Tollon, F.,1999. Geological source and use of rotary millstones from the Roman iron-making site of Les Martys (Montagne Noire, France). Eur. J. Mineral. 11,757e762.

Pavolini, C., 1986. La vita quotidiana a Ostia. Ed. Laterza, Bari.Peacock, D.P.S., 1980. The Roman millstone trade: a petrological sketch. World

Archaeol. 12 (1), 45e53.Peacock, D.S.P., 1985. Archaeology of Pantelleria, Italy, Nat. Geog. Soc. Res. Rep., prior

to 1985. National Geographic Society, Washington D.C, pp. 567e579.Peacock, D.S.P., 1986. The production of Roman millstones near Orvieto, Umbria,

Italy. Antiq. J. 66 (1), 45e51.Peacock, D.P.S., 1989. The mills of Pompei. Antiquity 63, 205e214.Peccerillo, A., 2005. Plio-quaternary Volcanism in Italy. Springer Verlag, p. 365.Renzulli, A., Antonelli, F., Santi, P., Busdraghi, P., Luni, M., 1999. Provenance

determination of lava flagstones from the Roman “Via Consolare Flaminia”Pavement (Central Italy) using petrological investigations. Archaeometry 41(2), 209e226.

Renzulli, A., Santi, P., Nappi, G., Luni, M., Vitali, D., 2002a. Provenance and trade ofvolcanic rock millstones from Etruscan-Celtic and Roman archaeological sites inCentral Italy. Eur. J. Mineral. 14, 175e183.

Renzulli, A., Santi, P., Serri, G., Luni, M., 2002b. The Euganean trachyte flagstones(“basoli”) used by the Romans in the middle-Adriatic coast (Marche, centralItaly): an archaeomtric study. Per. Min. 71, 189e201. Special Issue.

Romano, R., Villari, L., 1973. Caratteri petrologici e magmatologici del vulcanismoibleo. Ren. Soc. It. Min. Petr. 29 (2), 453e484.

Santi, P., Renzulli, A., 2006. Italian volcanoes as landmarks for the spreading of tradenetworks during the Etruscan and Roman periods: case study. Acta Vulcan-ologica 18 (1e2), 133e140.

Santi, P., Antonelli, F., Renzulli, A., Pensabene, P., 2004. Leucite phonolite millstonesfrom the Orvieto production centre: new data and insights into the Romantrade. Periodico di Mineralogia 73, 57e69. Special issue 32� IGC.

�Sebesta, G., 1974. La via dei mulini e Dall'esperienza della mietitura all'arte dellemacinare, Edizioni Museo degli usi e costumi della gente trentina, San Micheledell'Adige.

Serri, G., 1990. Neogene-Quaternary magmatism of the Tyrrhenian region: char-acterization of the magma sources and geodynamic implications. Mem. Soc.Geol. It. 41, 219e242.

Tanguy, J.C., Condomines, M., Kieffer, G., 1997. Evolution of the Mount Etna Magma:constraints on the present feeding system and eruptive mechanism. J. Volcanol.Geotherm. Res. 75, 221e250.

Tenore, M., 1883. Ragguagli delle peregrinazioni botaniche effettuate dal Cav. Ten-ore nel 1882, Il progresso della Scienza, VI, a. II.

Tozzi, P., Oxilia, M., 1981. Le pietre di Pavia romana. Bollettino della Società Pavese diStoria Patria 81, 3e44.

Trua, T., Esperança, S., Mazzuoli, R., 1998. The evolution of the lithospheric mantlealong the N. African plate: geochemical and isotopic evidence from thetholeiitic and alkaline volcanic rocks of the Hyblean plateau. Contrib. Mineral.Petrol. 131, 307e322.

Trua, T., Serri, G., Marani, M.P., 2003. Lateral flow of African mantle below thenearby Tyrrhenian plate: geochemical evidence. Terra Nova 15, 433e440.

Villari, L., 1974. The island of Pantelleria. Bull. Volcanol. 38, 680e724.Volterra, V., Hancock, R.G.V., 1994. Provenancing of ancient Roman millstones. J.

Radioanal. Nucl. Chem. 180 (1), 37e44.Volterra, V., 1997. Provenancing of the millstones. In: Simpson, C.J. (Ed.), The

excavations of San Giovanni di Ruoti: vol. 2, the small finds. Phoenix Supple-mentary, vol. 35. University of Toronto Press, pp. 75e82.

Williams-Thorpe, O., 1988. Provenancing and archaeology of Roman millstonesfrom the Mediterranean area. J. Archaeol. Sci. 15, 253e305.

Williams-Thorpe, O., Peacock, D., 1995. The quern-stone remains. In: Barker, G.(Ed.), The Biferno Valley Survey e The Archaeological and GeomorphologicalRecord. Leicester University Press, pp. 141e142.

Williams-Thorpe, O., Thorpe, R., 1989. Provenancing and archaeology of Romanmillstones from Sardinia (Italy). Oxford J. Archaeol. 8, 89e113.

Williams-Thorpe, O., Thorpe, R., 1990. Millstone provenancing used in tracing theroute of a 4th century BC Greek merchant ship. Archaeometry 32 (2), 115e137.

Williams-Thorpe, O., Thorpe, R., 1991. The import of millstones to Roman Mallorca.J. Roman Archaeol. 4, 153e159.

Williams-Thorpe, O., Thorpe, R., 1993. Geochemistry and trade of Eastern Mediterra-neanmillstones from theNeolithic to Romanperiods. J. Archaeol. Sci. 20, 263e320.

Zantedeschi, C., 1994. New RbeSr radiometric data from Colli Euganei (North-Eastern Italy). Mem. Sci. Geol. 46, 17e22.

F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e20922092