Mediterranean Trade of the Most Widespread Roman Volcanic Millstones from Italy and Petrochemical Markers of Their Raw Materials

Journal of Archaeological Science 37 (2010) 2081e2092

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Journal of Archaeological Science

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

Fabrizio Antonelli*, Lorenzo Lazzarini

Laboratorio di Analisi dei Materiali Antichi (LAMA) e Dip. Storia dell'Architettura, Università IUAV di Venezia, San Polo 2468, 30125 Venice, Italy article info abstract

Article history: The petrochemical study of millstones can contribute to improve the archaeological research into Received 29 October 2009 reconstruction of ancient communication routes and trade networks. Volcanic rocks are geographically Received in revised form restricted and rather rare in the Mediterranean regions, and during the Roman period Italian volcanoes 6 February 2010 were important sources of raw materials for millstones, so the task of determining their geological origin Accepted 15 February 2010 is relatively straightforward. The Italian vesicular volcanics most frequently employed for this purpose were: trachytes from Euganean Hills (Veneto), leucite-bearing lavas from the Vulsini Volcanic District Keywords: (Latium), basic-intermediate leucite-bearing lavas from Somma-Vesuvius (Campania), silica undersatu- Mediterranean trade Italy rated lavas from Monte Vulture Volcano (Basilicata), a rhyolitic ignimbrite from Sardinia and basic Algeria products from Mount Etna and the island of Pantelleria (Sicily). This paper contains a general outline of Cuicul the trade network for each volcanic typology used for millstones during the Roman period e updated Roman millstones with data concerning the leucite-bearing lavic items discovered in the archaeological sites of the ancient Lavas Cuicul (now Djemila, Algeria) e together with a summary of their petrographic and geochemical features. Petrography Ó 2010 Elsevier Ltd. All rights reserved. Provenancing

1. Introduction or iumentaria; donkeymills). As proposed by Antonelli et al., 2001, re-interpreting Varro (the Latin scholar of the first century BC) It is generally acknowledged that archaeometric research on rotary millstones (molae versatiles) were most probably invented mills and millstones found in the Mediterranean area is an (no later than the fourth century BC) in Volsinii veteres (present-day important means for the identification of the production sites of Orvieto), the famous Etruscan village, and not simply in Volsinii these artefacts and for the rediscovery of important trade networks (or Volsinii novi, now Bolsena), the Roman city built in the first half of protohistory and history. During the Roman age, hourglass- of the third century BC close to Bolsena Lake, ca 8 km NE of Orvieto. shaped or flat, cylindrical rotary millstones were exported to and Rotary millstones hourglass-shaped are also known as Pompeian- imported from many provinces of the Empire, including Germany, style millstones after the site where they occur so frequently and France, Italy, Spain, Portugal, Morocco, Tunisia, Libya, Algeria, were first discovered (i.e. Pompeii-Naples; Peacock, 1989; Buffone Cyprus and Turkey (cf. Williams-Thorpe, 1988; Antonelli et al., et al., 2003). Other famous Italian archaeological sites where 2001, 2005 and bibliography therein). Most of these Roman mill- well-preserved examples have been discovered include Ostia stones discovered in archaeological sites throughout the Mediter- Antica (Rome) and Aquileia (Udine). They were a very popular item, ranean are made of volcanic rock. In fact, lavas are generally wear- highly prized in Roman bakeries and military settlements of the resistant and they are particularly suitable for milling because of Imperial provinces. Shipwrecked cargoes of millstones such as that their abrasive property (hard enough not to contaminate the flour of Sec (Mallorca, Spain; Williams-Thorpe and Thorpe, 1990), testify unduly) and rough vesicular surface that provides a good grinding both to their importance in the Roman period and to the fact that capacity. The mills most commonly used by the Romans were up to they were traded throughout the eastern and western Mediterra- 1.5 metres high (Fig. 1) and typically consisted of an hourglass- nean. Fortunately, seeing that volcanic complexes occur in few shaped (double-cone) upper stone (catillus) resting on the conical regions of the Mediterranean basin, volcanic rocks exploited for lower stone (meta)(Moriz, 1958). The catillus was turned on the millstones may be very important markers for reconstruction of meta by means of a bar pushed by slaves or a donkey (mola asinaria ancient commercial and communication routes. Old and recent works (Peacock, 1980, 1986, 1989; Ferla et al., 1984; Williams- Thorpe, 1988; Williams-Thorpe and Thorpe, 1989, 1990, 1991, * Corresponding author. 1993; Lorenzoni et al., 1996, 2000a,b; Oliva et al., 1999; Antonelli E-mail address: [email protected] (F. Antonelli).

Table 1 Whole rock major oxides (wt%) and trace elements (ppm) analyzed for Roman lavic millstone 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 from the Orvieto quarries (after Antonelli et al., 2001) is reported for the purposes of comparison. Standard-deviation (s) of the average values OR-AV with respect to the quarry samples of Antonelli et al. (2001) are also reported. Analyses were performed at 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 0.36 Al2O3 20.00 18.60 19.85 21.42 0.13 Fe2O3 4.37 3.77 3.41 4.37 0.15 MnO 0.16 0.14 0.13 0.13 0.01 MgO 0.83 0.71 0.79 0.81 0.03 CaO 3.84 4.86 4.91 3.57 0.09

Na2O 2.98 3.27 2.63 2.79 0.42 K2O 8.48 8.25 10.55 9.95 0.30 TiO2 0.53 0.47 0.41 0.50 0.02 P2O5 0.13 0.16 0.25 0.10 0.01 LOI 2.86 2.85 2.78 ee

Total 99.38 97.68 99.71 99.99 e

K2O/Na2O 2.85 2.52 4.01 3.57 e

ppm V 143 120 114 125 19.45 Cr <10 <10 <10 2.67 1.0 Co 6.50 5.70 5.80 5.56 0.3 Ni <5 <5 <5 4.00 0.9 Rb 278 282 396 352 40.0 Sr 2100 2170 1865 1947 61.0 Y 39353039 1.6 Zr 811 649 558 730 69.0 Nb 54.1 48.0 36.6 45.0 1.9 Ba 2300 2430 2120 2232 44.0 La 204 183 144 183 7.0 Ce 394 316 255 325 12.0 Nd 121 108 87 107 4.0 Sm 18.05 16.05 13.10 16.10 0.50 Gd 17.00 15.00 12.15 11.30 0.60 Dy 8.17 7.20 6.04 7.18 0.32 Er 4.61 4.22 3.38 3.42 0.13 Yb 4.05 3.64 2.96 3.35 0.12 Lu 0.57 0.52 0.42 0.51 0.02 Fig. 1. Classical Pompeiian-style millstones. (a) Pistrinum of Pompeii; (b) Aquileia, Hf 13.10 11.60 9.50 10.80 0.40 Archaeological Museum; (c) Pistrinum of Ostia Antica. Th 144 126.5 95.6 160 9 et al., 2000, 2001, 2004, 2005; Renzulli et al., 2002a; Santi et al., 2004; Buffone et al., 2003) have combined to establish a useful petrographic, geochemical and historical database on the source chieﬂy rhyolitic ignimbrite from Mulargia and, to a very minor areas for the grinding tools used in Mediterranean countries from extent, the grey vesicular subalkaline basalts from different parts of the Neolithic to the Roman periods. the island (not considered here); (vi) hawaiites, mugearites and The purpose of this paper is to give a concise overview of the basalts from Etna (Catania e Sicily) as well as, to a minor extent, main Italian volcanic rocks exploited by the Romans in the manu- some other Sicilian basic lavas from Hyblean Plateau and the facture of exported millstones as well as of their trade network. The islands of Pantelleria, Ustica and Lipari. However, according to the general outline is updated with new data referring to leucite archaeological and archaeometric evidence, volcanics (iii), (v) and phonolite mills discovered at the archaeological site of ancient (vi) were generally preferred by Romans for export on a medium- Cuicul (now Djemila, Algeria) (cf. Figs. 4e6 and Table 1). large scale, (i)e(ii) were exported on a medium-to-small scale, whereas the lavas from Vulture (iv) were seldom transported far 2. Quarrying areas and circulation of the artifacts from the production centres and basically employed locally and on a small scale. The Romans exploited several Italian lava sources (Fig. 2), generally vesicular and so relatively easy to work, to produce 2.1. Trachytic rocks from the Euganean Hills e Venetian Volcanic millstones and rotary querns; judging by the archaeological ﬁnds Province the most widespread were (from northern to southern Italy): (i) Na-trachytes from the Euganean Hills (Padua e Veneto); (ii) leucite The Euganean Hills, located in North-Eastern Italy (province of phonolites from quarries in the Vulsini Volcanic District (near Padua) within the Venetian Tertiary Volcanic Province, comprise 81 Orvieto e Latium); (iii) leucite basaltic trachyandesites of Somma- domes whose origin is related to the extensional tectonic regime of Vesuvius (Naples e Campania) and (iv) tephrites-foidites from the South-Alpine foreland (De Pieri et al., 1983) and the extensive Vulture (Potenza e Basilicata); (v) volcanic rocks from Sardinia, eruptive activity that took place from the late Paleocene to the late F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 2083

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 of volcanic 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 Cristofolini et 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 (hawaiites and mugearites); (8) Edge of the Valle del Bove; (9) Major faults. 2084 F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092

Oligocene. Volcanic and sub-volcanic products range from subor- was also inferred (Antonelli et al., 2001) that at ca 10 km ESE of dinate basalts to intermediate and acidic lithotypes, mostly the Orvieto quarries, at the confluence of the Tiber and Paglia trachytes and rhyolites with a moderate Na-alkaline magmatic Rivers, the fluvial port of Pagliano was the main collecting point affinity. The latter crop out in the central part and at the edge of the for the millstone trade (they were probably shipped as ballast with area respectively and testify to the change in magmatic activity in wheat loads) along the River Tiber. This latter was a natural fluvial the Lower Oligocene (Zantedeschi, 1994). Euganean Trachytes have waterway which enabled the Orvieto artefacts to be transported been among the most widely distributed stones of NE Italy since down to the Tyrrhenian Sea (Pavolini, 1986; Antonelli et al., 2001; ancient times. They were already used by the Paleo-Venetian Renzulli et al., 2002a). Similarly, the port of Ostia Antica, located at populations in the seventh century BC for stelae (preserved in the the estuary of the River Tiber, probably represented the starting Archaeological Museums of Este and Padua) and mills (Antonelli point of the leucite phonolite millstones for their journeys along et al., 2004). The Romans occupying the Po Valley from the the different Mediterranean routes.1 The strategic position of the second century BC used it much more abundantly for the same quarries and the high grinding performance of these rotary purposes and for architectural elements (columns, capitals, lintels, millstones (due to the high vesiculation and intrinsic abrasive pillars, etc.), water pipes, bridges and to pave Venetian, Istrian and capacity of the mineralogical assemblage of the rock as well as to Emilian roads (several sections of the Via Aemilia were paved with its durability) only partially explains why they were so frequently polygonal trachytic blocks; Renzulli et al., 1999, 2002b). In Roman exported to faraway provinces of the Roman Empire, also to places times the stone also reached distant towns such as Ticinum (Pavia) where fairly similar lavas outcrop and were used to produce the (Tozzi and Oxilia, 1981), Mediolanum (Milan), Tergeste (Trieste), same items most likely cheaply because of lower transportation Fanum Fortunae (Fano; Renzulli et al., 1999) and Ankon (Ancona; costs (i.e. Pompeii). Probably, apart from commercial reasons, this Renzulli et al., 1999): these towns form a triangle within which important trade involving the pistrina of all the western Medi- trachyte is very often found. In the same period, Euganean trachytic terranean (Fig. 3a) depended on historical and symbolic aspects millstones and rotary-millstones were manufactured and spread related to the renown of the place where this kind of millstone throughout the X Regio Augustea, Venetia et Histria (Antonelli et al., was invented. 2004; Antonelli and Lazzarini work in progress) also reaching some localities of ancient Aemilia and Picenum (Marche) regiones (i.e., 2.3. Leucite basaltic trachyandesites from Castello di Cisterna Fossombrone and Urbisaglia e Renzulli et al., 2002a; Santi and quarry e Somma-Vesuvius Complex Renzulli, 2006). Among the 70 open-pit trachyte quarries identified in the field by Capedri et al. (2000), the sites where exploiting The leucite-bearing lavas from the Somma-Vesuvius, specifi- activity was particularly important were Monselice, Monte Rosso, cally those outcropping and exploited close to Castello di Cisterna Monte Oliveto, Monte Merlo, Monte Lispida, Monte Alto and Monte (Naples; Fig. 2), were indicated as the probable rock used for the Altore (Fig. 2). The trade towards the south was quite easy to carry hourglass millstones of ancient Pompeii from the end of the out (especially from the Monselice area) along the Mid-Adriatic nineteenth century (Tenore, 1883). One century later, Peacock coast and also throughout a system of drainage channels joining the (1980, 1989), basing his opinions both on hand specimens and hills to the paleo-Adige and the Brenta Rivers (Renzulli et al., 1999, typological comparison with volcanic millstones from Orvieto 2002b), while the connections between Euganean sources and the found at Ostia, was the first to suggest that only a part of those regions to the east could be effected by using the fluvial and discovered at Pompeii were made from the Vesuvius raw mate- maritime routes that had operated in this part of Caput Adriae since rials. More recently, Buffone et al. (2000, 2003), in the first protohistoric times. detailed archaeometric studies of this topic, stated that more than 60% of the Pompeiian hourglass millstones were produced at 2.2. Leucite phonolite from Orvieto e Vulsini Volcanic District Orvieto (infra) while fewer than 40% are made of local leucite basaltic trachyandesites belonging to the oldest eruptions of In the Mediterranean area, the use of leucite-bearing lavas was Somma-Vesuvius (30 ka ago; Peccerillo, 2005; these products are particularly widespread. Millstones and rotary querns produced almost wholly covered by the younger volcanic formations) and from these lavas have been discovered in Italian archaeological cropping out at Castello di Cisterna (near the Circumvesuvius sites (e.g., Aquileia e unpublished data e Luni, Veio, Ostia, railway station) and outside the walls of Pompeii, east of the Ercolano, Pompeii, Paestum and in Sicily; Antonelli et al., 2001; Amphitheatre. They also pointed out that these volcanic rocks Santi et al., 2004 and bibliography therein) as well as in other correspond to the so-called ottavianiti of Johansen (1937), a name Mediterranean regions such as Iberia, France, Cyprus, Tunisia, nowadays no longer used. Working from the suggestion of Sebesta Tripolitania, Cyrenaica (Peacock, 1980, 1986; Williams-Thorpe, (1974) on the presence at Aquileia of Somma-Vesuvius rock mill- 1988; Oliva et al., 1999; Antonelli et al., 2001, 2005) and Algeria stones, Buffone et al. (2003), on the basis of a morphological (Djemila, ancient Cuicul; new data included in this work). On the examination of the mills conducted simply on the pictures basis of fieldworks and archaeological studies Peacock (1980, annexed to the Sebesta paper, stated both that Vesuvius must have 1986) concluded that the main quarry and production centre of been an export area for millstones and that there must have been leucite-bearing Roman millstones was located close to Orvieto a trade route for these items from Naples to Aquileia (UD e Friuli). (between Sugano and Buonviaggio; Fig. 2) in the Vulsini Volcanic We are currently carrying out a detailed petrographic and District (0.6e0.125 Ma; Nappi et al., 1998; Peccerillo, 2005). The geochemical study on the Aquileia millstones. However, there is so first detailed petrographic and geochemical database on this far no significant archaeological-archaeometric evidence to quarry with a clear archaeometric goal was created by Antonelli support this conclusion or to suppose the existence of trade on et al. (2000, 2001). The data confirmed Peacock's suggestion and a large or medium scale. In fact, hourglass millstones from this revealed the local use of this rock for some oval saddle-querns region have been found only in Campania and at Grumentum already in the ninth century BC. Later on, several petro-archaeo- (Basilicata; Lorenzoni et al., 2000a,b). metric works (Renzulli et al., 2002a; Buffone et al., 2003; Santi et al., 2004; Antonelli et al., 2005) showed unequivocally that the leucite phonolite quarried near Orvieto is the most widely 1 We underline that all the rotary-millstones present in the big bakery of Ostia used lava for manufacturing millstones in the Roman period. It Antica come from Orvieto (Santi et al., 2004). F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 2085

Bronze Age to Roman times and beyond, but use and export of these items were just regional (Lorenzoni et al., 1996, 2000a,b). Roman millstones made of tephrite-foiditic lavas from Vulture have been detected in a few Roman sites of the southern Italian mainland, e.g., Basilicata, Molise and Apulia regions (i.e., Egnatia, S. Giovanni di Ruoti, Biferno Valley, Cannae, Altamura Gravina di Puglia; Volterra and 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 manufactured in several (unknown) localities scattered on the outcropping area of the small ﬂows of the vesicular lavas, particularly on the north-eastern and south-eastern slopes of the volcano. The same authors found excavation signs on tephrite blocks between the villages of Melﬁ and Rapolla.

2.5. Rhyolitic ignimbrite from Mulargia (Sardinia)

Sardinia was an important millstone production centre and a source of millstone trade during the period of Roman settlement. Studies of Roman millstones on the island showed that the Pompeiian type is the most common, whereas cylindrical hand querns occur more rarely (Peacock, 1980; Williams-Thorpe and Thorpe, 1989). The great majority of these items are made of a distinctive reddish rhyolitic ignimbrite and, to a very minor extent, of grey vesicular lavas of basic-intermediate composition. Following Williams-Thorpe and Thorpe (1989), there are several areas on the island where archaeological, historical and local tradition indicate a possible millstone production in the past. In particular, the rhyolitic millstones are from a single source of Oligocene-Miocene ignimbrite cropping out at Mulargia (called Molaria in Roman times; Meloni, 1975), a village near Macomer (west-central Sardinia; Fig. 2), while the millstones made of intermediate-basic lavas have varied sources within Tertiary and, above e Fig. 3. (a) Geographic distribution of leucite phonolite millstones from Orvieto, inferred all, Pliocene Pleistocene volcanics, i.e.: Monte Arci (west Sardinia), through detailed petrological studies (full circles) or hand specimens/quick petrography ca 30 km south of Oristano; Monte Teccu, in the south-eastern (asterisks). The Orvieto production centre (here located as a stylized rotary millstone) sectors of the island; Montiferro and Punte Luzzanas (west-central and the River Tiber (bold line in central Italy) are also located. 1. Cyrene and 2. Leptis Sardinia), southwest of Macomer; Orroli and Nurri (southern Magna (Libya; Antonelli et al., 2005); 3. Sabratha (Libya; Antonelli, unpublished data); 4. Sardinia), ca 50 km north of Cagliari and some others. However, on El Djem and 5. Carthage (Tunisia, Peacock, 1980); 6. Cuicul (Djemila, Algeria; present study); 7. Palermo (Williams-Thorpe, 1988); 8. Halaesa (Peacock, 1980); 9. Grumentum the basis of the archaeometric studies (Peacock, 1980; Williams- (Lorenzoni et al., 2000b); 10. Paestum (Peacock, 1980,1989); 11. Pompeii (Peacock, 1989; Thorpe, 1988; Williams-Thorpe and Thorpe, 1989) we can Buffone et al., 2003); 12. Herculaneum (Peacock, 1980, 1989); 13. Mondragone conclude that, starting from the 1st century AD, only the Mulargia (Williams-Thorpe, 1988); 14. Biferno Valley (Williams-Thorpe and Peacock, 1995); 15. millstone production area is clearly proven as a major source and Ostia (Santi et al., 2004); 16. Anguillara (Peacock, 1986); 17. Veii (Peacock, 1980); 18. fi Suasa (Santi et al., 2004); 19. Fossombrone (Renzulli et al., 2002a); 20. S.Angelo in Vado shows clear evidence of signi cant Roman trade, whereas (Antonelli et al., 2001); 21. Colombarone (Santi et al., 2004); 22.Pesaro (Antonelli et al., millstones from all the other Sardinian localities (e.g., the sub- 2001); 23. Lucca (Peacock, 1989); 24. Luni (Peacock, 1980); 25. Cannetolo di Fontanellato alkaline basalts from Monte Arci) were merely exploited locally or (Santi et al., 2004); 26. Concordia (Donner, 1993); 27. Aquileia (unpublished data; work regionally during the Roman period. Mulargia millstones, almost in progress); 28. Magdalensberg, Klagenfurt (Carinthia; T. Gluhak, personal communi- exclusively hourglass-shaped, were widely exported in the western cation); 29. Carnuntum / Bad Deutsch-Altenburg (Austria; T. Gluhak, p.c.); 30. Les Martys (Oliva et al., 1999); 31. Empuries; 32-35. Badalona, Barcelona, Carthagena, Zar- Mediterranean (particularly towards North-Africa) from Morocco agoza (Gimeno et al., 2010); 36. Astorga (Peacock, 1986, 1989); 37e38. Nea-Pafos & (Volubilis e unpublished data e and Tetouan; Williams-Thorpe, Nicosia, Cyprus island (Antonelli, quick petrography) (b) Geographic distribution of 1988; Williams-Thorpe and Thorpe, 1989) to Sicily (Segesta, Sardinian ignimbrite millstones from Mulargia (here located as a stylized rotary mill- Solunto, Selinunte and Megara Iblea) passing through Spain stone) in the Western Mediterranean area. After Williams-Thorpe and Thorpe, 1989, e modified. 1. Ampurias; 2. Tetouan musum; 3. Pollentia (Mallorca; Williams-Thorpe and (Ampurias and Mallorca), Algeria (Djemila unpublished data), Thorpe, 1991)4e10. Sassari; San Pietro di Sorres; Sant'Elena; Monte Zuighe; Sa Pattada; and Tunisia (Utica, Carthage, Musti, Sousse and Gightis; Williams- Mulargia; Tharros; 11. Segesta; 12. Solunto; 13. Megara Hyblea; 14. Selinunte; 15. Utica; Thorpe and Thorpe, 1989). Peacock (1980) first supposed a trade 16. Carthage; 17. Musti; 18. Sousse Museum; 19. Gightis; 20. Cuicul (Djemila, Algeria; in millstones between Sardinia and North Africa from the Roman to Antonelli and Lazzarini, quick petrography); 21. Volubilis (Morocco; Antonelli and Byzantine periods remembering also that the island was under the Lazzarini, quick petrography). control of Carthage during the Vandal period. This trade (partially and indirectly confirmed also by the presence of columns made of 2.4. Tephrites-foidites from Vulture (Potenza e Basilicata) Sardinian pink granite in many of the above-mentioned sites) generally shows a steep fall in the frequency of occurrences as the The Mount Vulture is an extinct volcano, mid-Pleistocene in age distance from Sardinia increases (Williams-Thorpe and Thorpe, (De Fino et al., 1986), rising on the southern Apennine Chain 1989); since this assumption does not appear to apply to (northern Basilicata; Fig. 2) and representing the easternmost Carthage, where a significant number of Pompeiian millstones magmatic event occurring during the Quaternary in central- made of Sardinian red-brown ignimbrite were found, Williams- southern Italy. It was an active millstone producing area from the Thorpe (1988) suggested that the town had a role as importer 2086 F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 and secondary distributor of Mulargia millstones in north Africa. 3.1. Euganean trachytes from the Venetian Volcanic The fact that Mulargia millstones (like those from Orvieto) were Province e They are mildly vesicular and of a colour that varies exported to parts of the Mediterranean where local lavas were through the different shades of grey present and used is an indication of their good reputation (Fig. 3b). According to the usual TAS classification diagram (Fig. 5a) these 2.6. Hawaiites and mugearites from Mongibello e Etna (and basalts rocks are principally transitional trachytes, seldom rhyolites or from Pantelleria) trachyandesites. Capedri et al. (2000) outlined mineralogical- petrographic, and chemical parameters characterising the trachytes As recognized by Williams-Thorpe (1988), Etnean hawaiites, of the most important historical quarries of the district. From mugearites and, to very minor extent, basalts were widely employed a compositional and textural point of view Euganean trachytes are in the production of millstones in antiquity (locally begun in the always porphyritic lavas (PI mainly from 20vol.%to40vol.%), Bronze Age; Ferla et al., 1984). We can assume e as also revealed by frequently not seriate and with glomerophyre aggregates. Anor- the finds of grinding tools dating back to the sixth century BC both in thoclase (Na-sanidine) > plagioclase > biotite Mg-kaersutitic the Apulia region (Lorenzoni et al., 2000a,b) and Istria and Italian- amphibole clinopyroxene are the main phases as phenocrysts Slovenian Karst (Antonelli et al., 2004) e that their trade was already (Fig. 4d); titano-magnetite, apatite and zircon are ubiquitous well organized during protohistory. Old and recent studies accessory minerals, whereas titanite only crystallises in a few (Williams-Thorpe, 1988; Volterra and Hancock, 1994; Lorenzoni trachytes (Monselice, Monte Merlo, Monte Trevisan). Phenocrysts et al., 1996; Buffone et al., 2000, 2003; Renzulli et al., 2002a; of allotriomorphic to euhedral anorthoclase, with crystals varying Antonelli et al., 2005) documented the presence of Roman mill- from 2 to 10 mm in size, frequently show evidence of internal stones made of these rocks not only within Sicily but also in central- melting (spongy texture) and very thin rims of new anorthoclase southern Italy (Marche, Apulia and Campania regions), Spain overgrowths. Euhedral to subhedral plagioclase phenocrysts are (Ampurias), Tunisia (i.e., Carthage, Thuburbo Maius, Utica, El often zoned and may also be rimmed by anorthoclase or Na-sani- Maklouba, Thapsus), Tripolitania and Cyrenaica (Lybia). Williams- dine. Biotite and, when it occurs (Monselice, Monte Merlo and not Thorpe (1988) noted the presence in North Africa (Tunisia) of arte- many others), amphibole are frequently oxidised and embayed-re- facts both from Mt. Etna and the Sicilian Na-alkaline volcanic islands absorbed. Fabrics are characterised by a holo-microcrystalline traditionally considered as the historical sources of basaltic s.l. mill- groundmass containing feldspar microlites (mainly of anortho- stones (i.e. Pantelleria and, to a very minor extent, Ustica) but clase) which sometimes show sub-parallel orientation due to unfortunately the paper does not present the complete chemical magmatic flow (pilotaxitic/trachytic textures; e.g. lavas from the data for all of the numerous millstones considered. Antonelli et al. Monselice and Monte Oliveto areas) as well as no fluidal orientation (2005) clearly identified Roman millstones manufactured with (felty texture; e.g. trachytes from Monte Cero, Monte Altore, Monte Pantellerian basalt and Etnean mugearite in the provinces of Tripo- Rosso, Monte Merlo, Monte Lispida and many other areas; Capedri litania (at Leptis Magna) and Cyrenaica (at Cyrene) which are among et al., 2000); small amounts of interstitial quartz and, occasionally, the southernmost production areas of grain in the Roman Empire. minute interstitial brownish glass may also be present in the Sicily and the adjacent small islands provided both obvious stop- groundmass. It is very common to see grey-black inclusions with over sites and important millstone sources on the traditional north- porphyric/granitoid/very weakly schistous fabric normally refer- south axis of the wheat trade (as mentioned by Strabo, VI.2.3: Etna). ring to trachyandesitic, gabbroic and cornubianitic composition, All the above-mentioned research papers indicate the Mongibello respectively (Lazzarini et al., 2008 and reference therein), that stratovolcano lava flows as the source of the Etnean raw material contain a larger amount of biotite, amphibole, pyroxene and exploited by Romans (Fig. 2). More specifically, it was ascertained magnetite than ordinary trachyte, and sometimes small amounts of that the most widely worked rocks were mugearites and hawaiites calcite; more rare are white-gray xenoliths of alkaline-rhyolites or belonging to the Mongibello Recente activity (Cristofolini et al., 1991), granitoid rocks. dating from 14 ka to the present (Peccerillo, 2005). Williams-Thorpe With regard to the chemical composition, general common (1988) first and Renzulli et al. (2002a) later suggested that the Fratelli features are K2O/Na2O ratio around 1, the absence of Nb-Ta negative Pii quarry (on the outskirts of Catania and dating from 693 BC) was anomalies and the presence of Q and Hy in the CIPW norm (Milani another of the Roman sites regularly exploited to work hawaiitic et al., 1999). As described by Capedri et al. (2000), trachytes of millstones. Following Buffone et al. (2003), who detected four individual quarrying areas are chemically quite homogeneous, but Etnean rotary-millstones at Pompeii, an additional possible Roman there is a rather wide chemical variability among the different sites, site for the production of mugearitic millstones may be found within which allows a good differentiation within the main Roman sour- the outcropping area of the Pizzi Deneri formation (Older Mon- ces. The authors consider TiO2, Zr, Th, Nb, Y, V, Rb, Sr and Pb gibello; Coltelli et al., 1994). particularly useful for discriminating and propose some valuable binary plots able to reduce all the main quarried trachytes to five 3. Useful petrographic and geochemical markers for fields (Th vs Sr; Fig. 8a) and to separate the stone varieties archaeometric purposes belonging to the fourth and fifth field groups (i.e., TiO2, Rb and Zr vs K2O; Y vs Nb and V; TiO2 vs Th and Zr; Fig. 8b). Petrographic and geochemical features here summarised have been generally taken from the recent literature considering at least 3.2. Leucite phonolite from Orvieto six samples (more often ten or tens) for each kind of lava. To avoid analytical bias, most of chemical data considered refer to the XRF From a petrographic point of view these rocks can be described analytical method for major and trace elements. In the case of the as grey to light-grey vesicular (vesicules around 10e15vol.%) leucite- leucite-bearing lavas from the Orvieto region we used the current bearing lavas, characterised by large euhedral leucite phenocrysts database which was produced by ICP-OES-MS methods (Antonelli (mainly 8e18 mm in size) which show complex zoning and et al., 2001). Anyway, a comparison between these data and those frequent inclusions of pyroxene plagioclase opaque minerals. produced through XRF on few samples of the same rock-type Among the most common micro- and phenocrysts (Porphyritic (Buffone et al., 2000) proved a satisfactory analytical compatibility Index 25e30vol.%) are also green clinopyroxene (Fig. 4a), sanidine, for the most discriminant elements. plagioclase (as strongly zoned single crystals, or as aggregates), at F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 2087

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 microcrystalline-pilotassitic groundmass (gdm) which is mainly feldspathic leucite Mg-Fe minerals; (B) leucite phonolite used for the catillus D3 found in Djemila; (C) Etnean mugearite showing plagioclase, clinopyroxene olivine (ol) phenocrysts in a microcrystalline-intergranular groundmass; (D) Euganean trachyte from the Roman site of Monte Rosso: anorthose (anr), plagioclase (pl), biotite (bt) and clinopyroxene (cpx) phenocrysts in a microcrystalline groundmass; (E) Vesuvian basaltic trachyandesite from the Castello di Cisterna area, showing augite (cpx), plagioclase olivine and leucite phenocrysts and aggregates embedded in a microcrystalline groundmass mainly made of feldspar, pyroxene and FeeTi oxides; (F) tephrite from the Vulture Volcano: haüyne (hyn) and clinopyroxene phenocrysts in a fine-grained groundmass. Crossed polarized light; long side of the pictures is 2.5 mm except for (F) for which is 5 mm. times rimmed by sanidine, and FeeTi oxides. The microcrystalline outcropping within the Roman Volcanic Province. La, Th, Sr versus pilotassitic to intergranular groundmass consists of sanidine, Ba binary diagrams proved to be the most efficient for this purpose leucite and plagioclase microlites with subordinate clinopyroxene (Antonelli et al., 2000, 2001; Renzulli et al., 2002a; Santi et al., and ore minerals (Fig. 4a). As regards geochemistry, these lavas are 2004; Fig. 6a). The possible overlapping of the Vulture and evolved members, strongly undersaturated in silica, belonging to Orvieto fields in the diagram Ba vs Sr can be easily resolved through the Roman-type high potassium series (HKS; Peccerillo, 2005; the petrography (discriminant presence of haüyne in the lavas from average K2O/Na2O > 2.5) of the Roman Magmatic Province Vulture; infra). (Appleton, 1972). According to the modal mineralogy and Total Similar petrographic (Fig. 4b) and geochemical (Figs. 5 and 6a) Alkali-Silica classification diagram (TAS; Le Maitre et al., 1989), they features have been found for two catillus (#D ¼ h: 42 cm, internal are essentially phonolites (Fig. 5a). More specifically, they show Ø: 25 cm; #D3 ¼ h: 37 cm, internal Ø: 24 cm) and one meta appreciable enrichment in light rare earths (LREE), La, Sr, Th and, (#D4 ¼ h: 30 cm, maximum Ø: 25 cm) discovered in the ancient Ba, together with Nb and Ti negative anomalies, which are all Cuicul (Algeria). Results of the petrochemical study conducted on typical features of the subduction-related Quaternary potassic them are summarised in Figs. 4e6 and Table 1. rocks from the north-west sector of the Roman Volcanic Province (Serri, 1990). As verified first by Antonelli et al. (2000, 2001), in the 3.3. Somma-Vesuvius leucite basaltic trachyandesites from Castello case of the rocks from the Orvieto quarries, their highest abundance di Cisterna of La (172e228 ppm), Sr (1823e2167 ppm), Th (136e178 ppm) and Ba (1957e2340 ppm) are very useful chemical fingerprints for They are highly porphyritic lavas (PI ca 50e65vol.%); augitic differentiating these leucite phonolites from the other similar rocks euhedral clinopyroxene (mainly 3 mm in size; Ømax 5 mm), 2088 F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092

the phonolitic tephrites. These rocks, as always for the potassic series (KS; Peccerillo, 2005) of the Roman Magmatic Province,are characterised by K2O/Na2O ratios varying from 1.5 to 2.5 (often < 1.8; Joron et al., 1987), absence of Ba and P negative anomalies (Serri, 1990), La 43e48 ppm, Sr 673e696 ppm and Ba 1449e1502 ppm (Buffone et al., 2000, 2003). Their mineralogical and chemical compositions suggest to classify they as shoshonites and allow these leucite-bearing lavas to be readily differentiated from 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 Vesuvius along the Tyrrhenian margin of Italy, Mount Vulture is located near the easternmost border of the Appennine compressive front. This peculiar structural setting is accompanied by a unique composition of magmas and derived alkaline rocks, which are characterised by both K and Na enrichment (Beccaluva et al., 2002)aswellasby common presence of haüyne in all the volcanic products (De Fino et al., 1986; Beccaluva et al., 2002; Peccerillo, 2005). Tephrite-foidite vesicular lavas (vesicles ca 35vol%) used for millstones show evident porphiritic texture (PI ca 30e35vol%) and are composed of phenocrysts mainly of green pyroxene and haüyne >> leucite and nepheline biotite and apatite (Fig. 4f). They are embedded in a very fine-grained groundmass in which opaque minerals, plagioclase, pyroxene, feldspathoids and occasionally K-fedspar may be recognizable. Pyroxene phenocrysts, generally abundant and zoned, have fairly irregular form and inclusions of haüyne, opaques and nepheline. Those of haüyne are common or abundant and usually appear smaller and more Fig. 5. (a) The alkali-silica classification (TAS) of both the six Italian volcanic millstone rounded than pyroxene. Their colour is typically blue at the rim. source rocks object of this paper and the analyzed leucite-bearing volcanic millstones Finally nepheline, leucite and biotite (which may be altered) from Cuicul (Algeria: full triangles). Diagram (after Le Maitre et al., 1989) includes the phenocrysts are commonly small in size. Using the TAS diagram subdivision of volcanic rocks into alkaline and subalkaline. The boundaries are as (Fig. 5a) these lavas fall in the tephrite, tephrifonolite and foidite follows: ¼Kuno, 1966; < ¼ Irvine and Baragar, 1971. Abbreviations: H: hawaiites; M: mugearites; TA: trachyandesites; T: trachytes; PB: picro-basalts; B: basalts; BA: basaltic fields in agreement with the petrographic classification (De Fino andesites; BT: basaltic trachyandesites; A: andesites; D: dacites; Te-Bs: tephrites and et al., 1986; Caggianelli et al., 1990; Beccaluva et al., 2002; basanites; PhTe: phono-tephrites; TePh: tephri-phonolites; Ph: phonolites; F: foidites; De Astis et al., 2006). Geochemistry reveals that they belong to R: rhyolites. (b) Na2O vs.K2O variation diagram for both the principal Italian volcanic the potassic alkaline series (De Fino et al., 1982, 1986) of the Roman raw 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- Magmatic Province, with K2O/Na2O variable, but frequently high bearing lava sources (Orvieto, Vesuvius, Vulture). Data referring to basic lavas from (always > 1) although haüyne is the dominant feldspathoid Pantelleria, Ustica and Hyblean Plateau are plotted for comparison with Etnean lavas. (Lorenzoni et al., 2000a). In these basic lavas the K/Na ratio is Separation among HK, K and Na series classically adopted for alkaline basic rocks (after similar to those of KS basic magmas (Fig. 5b), but the enrichment of Middlemost, 1975), is plotted too (grey dashed lines) to show the Na-affinity of all the most incompatible elements and the degree of silica under- Sicialian 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, Vulsini saturation are close to those of HKS magmas (De Fino et al., 1986). Volcanic Discrict); Cristofolini et al., 1991 (circles: hawaiites and mugearites from the CaO and TiO2 vol% are mainly 8.1e12.4 and 0.8e1.4, respectively, Mt. Etna, Mongibello Recente); Buffone et al., 2000 (squares: leucite basaltic tra- while, with regard to trace elements, the Zr values are generally chyandesites from Castello di Cisterna, Somma-Vesuvius); De Fino et al., 1986; between 305 and 570 ppm, V varies roughly from 180 to 270 ppm, Williams-Thorpe, 1988 and Beccaluva et al., 2002 (crosses: tephrites-foidites from Vulture Volcano; Capedri et al., 2000 (open diamonds: trachytic lavas from Euganean Sr approximately from1600 to 2850 ppm, Rb from 70 to 170 ppm, Hills); Williams-Thorpe, 1988 and Williams-Thorpe and Thorpe, 1989 (asterisks: Ba from 1700 to 2800 ppm and Y roughly from 40 to 60 ppm rhyolitic ignimbrite from Mulargia); Civetta et al., 1984, 1998 (rotated crosses: alkaline (De Fino et al., 1986; Lorenzoni et al., 2000a; Beccaluva et al., 2002; and transitional basalts from the island of Pantelleria); Trua et al., 1998 (full gray De Astis et al., 2006). In the Mediterranean basin as a whole these asterisks: alkaline basalts from the Hyblean Plateau); Trua et al., 2003 (crossed mineralogical and geochemical compositions (cfr. Figs. 6a and 7) squares: basic lavas of Ustica). Separation among HK, K and Na series classically adopted for alkaline basic rocks (after Middlemost, 1975), is plotted too (grey dashed are peculiar just to Mt. Vulture, the only volcano to have such lines) to show the Na-affinity of the Sicialian lavas. abundant haüyne in the emitted products (among all the volcanoes of the Roman Magmatic Province negligible amounts of haüyne are idiomorphic leucite (Ømax 4e5 mm), labradoritic-bytownitic present only in the Roccamonfina lavas) (Lorenzoni et al., 2000a). plagioclase (Ømax 2 mm) and olivine (Ømax 1.5 mm) are the most abundant phenocrysts respectively (Fig. 4e); occasionally rare 3.5. Rhyolitic ignimbrite from Mulargia (Sardinia) sanidine may also be present. Pyroxene, leucite and plagioclase may each form polycrystalline aggregates. The microcrystalline This ignimbrite has a distinctive red colour with paler fiamme groundmass consists (in decreasing order of abundance) of feld- and contains many sharp edged vesicles (usually about 1e3mmin spar, pyroxene, leucite, FeeTi oxides, phlogopite and apatite. size), very often lined with a typical green mineral, supposed to be In the TAS diagram (Le Maitre et al., 1989; Fig. 5a) they fall celadonite (Williams-Thorpe and Thorpe, 1989) probably mixed essentially in the basaltic trachyandesites field, seldom in that of with some kind of zeolite. In thin-section it exhibits a brown-red F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 2089

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 volcanic millstones 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 for comparisons 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 from the 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; Trua et 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); De Fino 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). glassy (often devitrified glass) groundmass, showing traces of flow of the archaeologists, archaeometric analyses concerning this kind structure (Peacock, 1980), embedding very rare phenocrysts of of volcanic millstones are very rare (few analyzed samples are quartz and andesine feldspar biotite opx. This rock outcrops in reported just in Williams-Thorpe, 1988 and Williams-Thorpe and the north-west of the Sardinia and belongs to the relatively high K Thorpe, 1989). calc-alkaline dacite-rhyolite lava series erupted during the OligoceneeMiocene (30e13 ka) subduction of lithospheric plate in 3.6. Etnean hawaiites and mugearites from Mongibello the SardinianeCorsican microplate environment, so it shows (and basalts from Pantelleria) chemical characteristics common to island-arc related rocks (Dostal et al., 1982; Peccerillo, 2005). Following data reported by Mugearites and hawaiites are generally grey to dark-grey Williams-Thorpe (1988) and Williams-Thorpe and Thorpe (1989) slightly vesicular (vesicles 10%) seriate lavas often characterised the Mulargia ignimbrite exhibits low concentrations of Cr by evident porphyritic texture (PI: 20e60 vol.% ca for mugearites; (ca 2e20 ppm); Rb ca 140e165 ppm; Sr ca 150e190 ppm, Y ca 30e50 vol.% ca for hawaiites). Mugearites have microcrystalline- 30e53 ppm; V ca 20e43 ppm; Zr ca 200e230 ppm, TiO2 around intergranular groundmass made up of plagioclase, opaque 0.60%, SiO2 ca 67e69; Al2O3 ca 14.9e16%; K2O/Na2O ratio roughly 1 minerals and less abundant pale-green or colourless clinopyrox- (frequently slightly < 1) and K2O þ Na2O 8%. Obviously, to prove ene. Phenocrysts and microphenocrysts are represented by pla- univocally a provenance from Mulargia, petrochemical analyses gioclase >> clinopyroxene > olivine > FeeTi oxides (Fig. 4c). should be always necessary for a scientific validation of the origin of Euhedral (labradoritic)-bytownitic plagioclases are the largest this high-silica rock (Figs. 6a and 7). Unfortunately, due to its ones (4e5 mm in size) and often feature spongy texture, deep general macroscopic aspect, supposed to be sufficiently distinctive embayments, glass and opaque inclusions. Augitic pale-green to identify it in hand specimens directly with the naked eye by most pyroxene is normally small in size (mainly 0.5 mm, sometimes up 2090 F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092

Fig. 8. (a): Sr vs.Th diagram for the discrimination of quarried sites of the trachytes in the Euganean Hills (ﬁelds and data from Capedri et al., 2000). Field 1: Monselice; Field 2: 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 the discrimination of the Euganean trachytes falling in field 4 of Fig. 8a (fields and data from Capedri et al., 2000). Gray filled circles refer to three Roman mills from Antonelli et al., 2004 and one Roman millstone from Aquileia (unpublished data).

As concerns the geochemical characters of mugearite, hawaiites from Mongibello Recente, they refer to original magmas related to an extensional within-plate regime and with a weak Na-alkaline Fig. 7. Discrimination among the six main Italian millstone source rocks considered in fi this paper using Zr and V (after Williams-Thorpe, 1988, modified). For comparison with af nity; This is shown, for example, by the Th/Nb (see, e.g., Fig. 8 of Etnean lavas, data referring to other basic Sicilian rocks are plotted too. The gray Beccaluva et al., 1991) and K2O/Na2O ratios (¼0.5; Peccerillo, 2005). broken line separates the acid from the basic-to-intermediate rocks. Data are from: In particular, useful fingerprints are represented by TiO2 < 2 wt. %, Williams-Thorpe, 1988; Trua et al., 2003; Peccerillo, 2005, for Pantelleria, Hyblean high Sr values (>1000 ppm) and Ba (>700 ppm) (Cristofolini and Plateau 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 “Mongibello Romano, 1982; Cristofolini et al., 1991; Peccerillo, 2005). Further- recente” lavas; Williams-Thorpe, 1988 and Beccaluva et al., 2002, for Mt. Vulture; more, Sr vs Ba (Fig. 6a), Nd, Sr vs TiO2 (Antonelli et al., 2004, 2005; Williams-Thorpe, 1988 and Williams-Thorpe and Thorpe, 1989, for Mulargia. Symbols Fig. 6b)orZrvs V(Fig. 7; after Williams-Thorpe, 1988, modified) are as in Figs. 5 and 6. Full triangles are the analyzed millstones from Cuicul. Small pale diagrams can be quite valuable for discrimination between our grey circles refer to Roman millstones analyzed by scholars cited in the text and to one basic lavas and those from other Etnean areas (tholeiitic basalts), unpublished trachytic millstone from Aquileia. Hyblean Plateau (alkaline and transitional basalts), Ustica (alkali- basalts, hawaiites and mugearites), and Pantelleria (alkaline and to 3.5 mm), whereas olivine phenocrysts are smaller (main- transitional basalts); these are virtually all possible sources for ly 0.5 mm in size) and show a rounded habit. Roman volcanic millstones. In particular, as reported by Williams- Hawaiitic lavas have microcrystalline-intergranular groundmass Thorpe and Thorpe (1990), Pantelleria was a producer of small, composed of plagioclase, clinopyroxene, olivine and FeeTi oxides. relatively simple millstones from at least the Bronze Age to the They include pheno- and microphenocrysts of euhedral sieved Roman period. Basaltic lavas outcropping as far as the coast in the plagioclase (up to 3 mm in size, with opaque and glass inclusions) > northern (at San Leonardo and Mursia; Civetta et al., 1984) and augitic green to brownish pyroxene (up to 2 mm in size and north-east parts of the island (at Le Balate; Villari, 1974; Civetta including oxides) sub-rounded olivine (around 1 mm in size; on et al., 1984) were the most probable flow sources. Specifically, the occasion in glomerophyric associations with clinopyroxene). dark-grey vesicular, olivine-basalts of San Leonardo, which are F. Antonelli, L. Lazzarini / Journal of Archaeological Science 37 (2010) 2081e2092 2091 characterised by a seriate porphyritic texture (PI 25e30 vol. %; susceptibility and its bearing on the provenance of stones of ancient artefacts. e phenocrysts: labradoritic- bytownitic plagioclase > augitic clino- J. Cult. Herit. 1, 341 364. Cinque, A., Civetta, L., Orsi, G., Peccerillo, A., 1988. Geology and geochemistry of the > pyroxene olivine), microcrystalline-intergranular groundmass island of Ustica (Southern Tyrrhenian Sea). Rend. Soc, It. Mineral. Petrol. 43, (plagioclase þ clinopyroxene þ FeeTi oxides olivine), chemical 987e1002. Civetta, L., Cornette, Y., Crisci, G.M., Gillot, P.I., Orsi, G., Requiejo, C.S., 1984. Geology, transitional/sodic affinity (K2O/Na2O ratio 0.3, TiO2 > 2 wt. % and < geochronology and chemical evolution of the island of Pantelleria. Geol. Mag. Sr 550 ppm; Villari, 1974; Civetta et al., 1984, 1998), were the raw 121, 541e562. material used to obtain some Roman millstones discovered in Civetta, L., D'Antonio, M., Orsi, G., Tilton, G.R., 1998. The geochemistry of volcanic North Africa, specifically in Tunisia and Libya (Peacock, 1985; rocks from Pantelleria Island, Sicily Channel: petrogenesis and characteristics of the mantle source region. J. Petrol. 39, 1453e1491. Williams-Thorpe, 1988; Antonelli et al., 2005). Coltelli, M., Garduño, V.H., Neri, M., Pasquarè, G., Pompilio, M., 1994. Geology of the As regards other possible Sicilian lava sources, the use of alkaline northern wall of Valle del Bove, Mt Etna (Sicily). Acta Vulcanol. 5, 55e68. and transitional basalts from Ustica and Hyblaean Plateau, as well Conticelli, S., Francalanci, L., Manetti, P., Cioni, R., Sbrana, A., 1997. Petrology and geochemistry of the ultrapotassic rocks from the Sabatini Volcanic District, as of andesites from the Aeolian island of Lipari is very rare outside central Italy: the role of the evolutionary processes in the genesis of variably the Sicilian district; very few Roman mills and grindstones made of enriched alkaline magmas. J. Volcanol. Geotherm. Res. 75, 107e136. these lavas have been identified on the Italian mainland Cristofolini, R., Corsaro, R.A., Ferlito, C., 1991. Variazioni petrochimiche nella fi (for example one possible grinding tool of Hyblean origin at successione etnea: un riesame in base a nuovi dati da campioni di super cie e da sondaggi. Acta Vulcanol. 1, 25e37. Fossombrone, Marches; Renzulli et al., 2002a) and in North Africa (a Cristofolini, R., Romano, R., 1982. Petrological features of the Etnean vocanic rocks. quern made of trachybasalt from Ustica is mentioned at Carthage Mem. Soc. Geol. It. 23, 99e115. by Williams-Thorpe, 1988). De Astis, G., Kempton, P.D., Peccerillo, A., Wu, T.W., 2006. Trace element and isotopic variations from Mt. Vulture to Campanian volcanoes: constraints for slab detachment and mantle inflow beneath southern Italy. Contribut. Mineral. 4. Conclusions 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 element The petrographic and geochemical features summarised above, data. Contribut. Bull. Volcanol. 45, 115e126. when used together (possibly integrated by critical historical- De Fino, M., La Volpe, L., Peccerillo, A., Piccarreta, G., Poli, G., 1986. Petrogenesis of Monte Vulture volcano (Italy): inferences from mineral chemistry, major and archaeological data too) may produce reliable results concerning trace element data. Contribut. Mineral. Petrol. 92, 135e145. the origin of the Italian raw material of the Roman volcanic De Pieri, R., Gregnanin, A., Sedea, R., 1983. Guida alla escursione sui Colli Euganei. millstones. This approach enables most millstones to be attributed Mem. Soc. Geol. Ital. 26, 371e381. Donner, M., 1993. La macina per cereali nel Veneto di età Romana. In: “Nel nome del to a geological source, if not ever with absolute certainty then pane”, Ed. Regione Autonoma Trentino-Alto Adige, pp. 391e405. surely with a fully acceptable degree of reliability. For three decades Dostal, J., Coulon, C., Dupuy, C., 1982. 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