Determining the provenance of black limestone artifacts using petrography,isotopes and EPR techniques: the case of the monument of Bocco

This paper investigates the provenance of the black limestone of the monument known as Bocco, named after the king of Mauretania who presented Silla with this work as a sign of his submission to the power of Rome. A multi-method approach, comprising petrographic observations, carbon and oxygen isotope composition and electron paramagnetic resonance (EPR) spectra characteristics, was used for this purpose. The monument is part of a reconstruction of a rectangular base (approx. 8 × 2 m) which is likely to have served as the base for a bronze statuary group and is currently composed of six blocks of limestone whose exterior is engraved with a fine frieze. The results of the different analyses were compared with the data of a published database of the most important black limestone quarries exploited during Roman times in the Mediterranean area. The petrographic and physico-chemical parameters did not prove to be very effective in determining the provenance of the black limestone of Bocco; the isotopes result even raised some uncertainty as to whether all six blocks came from the same quarry, though this doubt was dispelled by the EPR data and, above all, by the evident petrographic similarity between them. Differences in the isotopic composition of the various blocks may be due to an in situ rock alteration process caused by interaction with an aqueous fluid. It was, however, impossible to determine with certainty the origin of the material of the stone artifact using the database available; it is possible that the black limestone of Bocco came from an ancient quarry that is likely to be located in north western Africa but has not yet been uncovered. An alternative hypothesis, according to which the limestone used for the monument of Bocco came from the ancient quarry of Ain el Ksir, one of the Tunisian quarries present in the database, is also discussed.     

A Multi‐Method Database of the Black and White Marbles of Göktepe (Aphrodisias), Including Isotopic,EPR, Trace and Petrographic Data

A database of the ancient marbles of Göktepe near Aphrodisias is reported, and includes 160 white, black and bichrome samples from 13 quarries and two waste deposits. The quarries are grouped into four districts. Districts 1 and 2, to the north, produced exclusively black or dark grey marbles (nero antico). Districts 3 and 4 produced white statuary marble. Nero antico and a black and white stone were also quarried in district 4, where the black marble surfaces again. The samples were characterized using petrography, isotopic analysis, EPR spectroscopy and trace analysis. The Göktepe white exhibits an unparalleled combination of fine grain, low EPR intensity and high strontium concentration that often allows easy identification. The isotopic values are less distinctive and similar to those for Carrara. In most cases, however, they are tightly grouped and also quite indicative. The black marbles exhibit a much weaker metamorphic overprint. With respect to the white marbles, they show analytical similarities but also notable differences. Therefore, establishing their provenance can be more difficult and may require the support of petrographic analysis. The results suggest that the Göktepe marbles were among the most prized and widespread statuary marbles used in Roman times, particularly from the early second century ad onwards.     

A MULTIDISCIPLINARY APPROACH TO THE CHARACTERIZATION OF ROMAN GRAVESTONES FROM AQUILEIA (UDINE,ITALY)*

The results of an archaeometric study on gravestone production in Aquileia (northeastern Italy) during Roman Republican times are reported here. The artefacts are made of limestone, quarried from the sedimentary sequence of the Trieste Karst (Carnican Alps, northeastern Italy), as testified by historical sources which refer to the ‘Roman Quarry’ at Aurisina. The rock types used for the gravestones are petrographically, geochemically and geochronologically homogeneous, and display similar faunal assemblages. In addition, their age is restricted to the Santonian – Lower Campanian. Comparisons between archaeological finds and rock specimens from various active and inactive quarries in this area suggest that quarrying during Roman Republican times was limited to a specific stratigraphic horizon of the sedimentary sequence, corresponding to the higher part of the ‘Roman Quarry’.     

Geochemical provenance analyses of Roman lava millstones north of the Alps: a study of their distribution and implications for the beginning of Roman lava quarrying in the Eifel region (Germany)

In Roman times, rotary querns and different types of millstones, driven either by horse-capstan or water power, were produced in the lava quarries of the quaternary volcanic Eifel region and exported to many parts of the Empire. The geographic distribution of Roman lava millstones from the Eifel region provides important information about trade patterns and, in cases of well dated millstones, also allows an estimate as to when the Roman lava quarrying in the Eifel region began. Sixty-two millstones from Germany, France and Austria were sampled and analyzed for major and trace elements by X-ray fluorescence. To determine their provenance, the millstone data was evaluated by a combination of geochemical discrimination and cluster and discriminant analyses using an extensive and detailed database of all Roman lava quarries in the Eifel region. An Eifel provenance could be confirmed for forty-four artefacts and, furthermore, determined down to the exact lava flow. The affiliation of the other artefacts to other possible regions where millstones of comparable lava were extracted was carried out on the basis of geochemical data from the literature. However, because of insufficient data, only assumptions about the regional provenance can be made. The origins of the other finds are assumed to be the Vogelsberg region, the Massif Central, Orvieto, and, possibly, the Pannonian Basin. A preliminary map of the distribution of Eifel millstones in Roman times based on these data is presented; the beginning of Roman lava quarrying can be constrained to 8–7 BC.     

Roman lava quarries in the Eifel region (Germany): geochemical data for millstone provenance studies

Roman millstones of assumed Eifel origin were produced and exported in huge quantities to many parts of Roman Europe and can be used as tracers for trade patterns in Roman times. This study presents for the first time a raw-material centred geochemical definition of the 13 well-known Roman basaltic lava quarries in the Quaternary East and West Eifel volcanic fields. The aim is to find a way to characterize the individual exploitation sites precisely by means of their geochemical composition and to recommend a standard procedure for further millstone provenance analysis. Based on major and trace element composition analyses by XRF, a differentiation of each quarry is achieved by using a combination of geochemical discrimination and cluster and discriminant analysis. Therefore, for provenance analysis of a unknown millstone sample the following procedure is recommended: (1) geochemical discrimination to check if it actually belongs to the volcanic Eifel quarries; (2) cluster analysis to check to which quarry or cluster of quarries the millstone can be affiliated; and (3) discriminant analysis to assign the sample to its quarry of origin with a certain confidence.     

PROVENANCE OF MEDIEVAL PIETRA OLLARE ARTEFACTS FOUND IN ARCHAEOLOGICAL SITES OF CENTRAL–EASTERN ITALY: INSIGHTS INTO THE ALPINE SOAPSTONE TRADE*

Medieval archaeological findings made of pietra ollare (basic and ultrabasic metamorphic rocks belonging to the greenschist facies) and coming from central–eastern Italy have been characterized through a petrological study (modal mineralogy, whole‐rock geochemistry, XRD and SEM–EDS analyses). The pietra ollare artefacts considered in this work consist of fine‐grained, grey to pale‐grey, magnesite‐bearing talc‐schists (i.e., soapstones). In order to determine their production centres, Alpine soapstones quarried in ancient times were selected on the basis of their mineralogical and textural compatibility with the archaeological findings. The mineralogy and chemistry (major and trace elements) contributed to establishing the ancient quarries of the Valchiavenna (central Alps) as the probable provenance area. This archaeometric investigation proves that Alpine artefacts made of pietra ollare spread to the south of the Po Plain during the Middle Ages. It can be inferred that the Alpine soapstone trade towards the Marche and Abruzzo regions was addressed through the main waterways: Lake Como, the Adda and Po Rivers and finally the Adriatic Sea.     

PROVENANCE DETERMINATION OF LAVA FLAGSTONES FROM THE ROMAN ‘VIA CONSOLARE FLAMINIA’PAVEMENT (CENTRAL ITALY) USING PETROLOGICAL INVESTIGATIONS*

Trachyte lava flagstones from the northernmost stretch of the Roman ‘Via Consolare Flaminia’pavement and trachyte lavas from the most exploited quarries in Roman times were compared from a petrological point of view. ‘Via Consolare Flaminia’was the most important route used by the Romans to reach northern Italy and all the northern provinces of the Empire. A provenance for the flagstones as coming from the trachyte quarries of the Euganean Hills (Veneto region, northern Italy) is suggested by the similarity of both the fundamental mineral assemblage and the major trace element geochemistry. The location of the quarries of the Euganean Hills next to the harbours of the northern Adriatic Sea strongly supports the hypothesis that the Romans carried the flagstones by ship towards the coasts of the central Adriatic Sea.     

THE JUDICIOUS SELECTION AND PRESERVATION OF TUFF AND TRAVERTINE BUILDING STONE IN ANCIENT ROME*

The Republican and early Imperial monuments of Rome are, for the most part, built of tuffs quarried from at least seven pyroclastic deposits erupted from nearby Monti Sabatini and Alban Hills volcanoes. Remarks by Vitruvius (2.7.1–5), field observations of the monuments, and petrographic and rock testing studies of samples from Roman quarries demonstrate that Roman builders developed a good knowledge of the diverse material properties of the tuffs over centuries of use and exposure. Measurements of compressive strength, specific gravity, water absorption and adsorption of water vapour confirm that the petrographic characteristics of each tuff lithology strongly influence its strength and durability. Early construction utilized weakly durable, soft or vitric tuffs such as Tufo del Palatino or Tufo Giallo della Via Tiberina that are susceptible to decay, as at Temple C (290 bc ) of the Largo Argentina Sacred Area. Late Republican structures, such as the Temple of Portunus (80–90 bc ), employed somewhat durable, vitric–lithic Tufo Lionato reinforced with travertine, a durable limestone quarried near Tivoli. Roman builders selected the material properties of the tuffs to advantage for specific structural elements within large public monuments of the first century bc and the first century ad , as at the tabernae of the Forum of Caesar (46 bc ), where an upper storey of lightweight Tufo Lionato is supported by robust, lithic–crystal Lapis Gabinus pillars and flat arches reinforced with travertine. The tuffs are not very durable building stones; Romans preserved them with protective stucco, and travertine and marble cladding. Their high water intake, coupled with direct exposure to rain, daily fluctuations in relative humidity and urban weathering at present makes them especially vulnerable to decay.     

Black limestone used in antiquity: recognizing the limestone of Teos

This paper documents the petrographic and isotopic characteristics of some black limestones that were exploited in antiquity near the ancient site of Teos in Ionia (south‐western Anatolia, Turkey). The best‐quality black limestone of Teos is represented by a series of step‐cut‐shaped blocks situated north of the Seferihisar–S??ac?k road, destined to be exported and used for architectural elements. The techniques used to study these blocks allow possible identification of the origin of Teos in ancient black stone artefacts. Nevertheless, petrographic and geochemical investigation on some black limestones that outcrop in the area near Teos has not firmly identified the quarry fronts from which these blocks were quarried away, but it supports the known hypothesis that Teian black limestones were found and quarried in conjunction with the Africano marble.     

ANCIENT EGYPTIAN LIMESTONE QUARRIES: A PETROLOGICAL SURVEY*

Ancient Egyptian limestone quarries in the Nile Valley occur in six geological formations of Palaeogene age. Samples were collected from 23 of the 48 known quarries, and analysed by thin-section petrography and X-ray fluorescence spectrometry. Results of the analyses show that the geological formations can be identified from rock texture and allochem types, and a plot of SiO₂/Al₂O₃ versus CaO/[CaO + MgO]. The application of these petrographic and geochemical parameters make it possible to determine the geographic provenance of limestone used in ancient Egyptian sculptures and monuments.     

The Asiatic marbles of the Hadrian's Villa at Tivoli

Multi-method provenance studies, including petrographic, isotopic, electron paramagnetic resonance and trace chemical analyses, have been carried out on 20 white, 9 black and 1 red artifacts purposely selected to investigate the use and distribution of sculptural marbles at the Hadrian's Villa. A large fraction of the marbles tested (21 samples, 70%) are shown to be from Asia Minor, mostly originating from the recently discovered site of Göktepe near Aphrodisias (15 or 71%). All the 9 black samples investigated and 6 out of 11 white Asiatic marbles are from Göktepe, the remaining being Docimium marble from Iscehisar (4 samples) and Aphrodisias marble from the city quarries (1 sample). The single red sculpture tested proved to be Carian red marble from the Iasos quarries, whereas non-Asiatic marbles include 3 Carrara and 6 Pentelicon samples. The selection of marbles tested is preliminary and incomplete, but, despite this, the results are noteworthy, especially since the marble of other sculptures from the Villa has already been identified as Göktepe. Together with other published results, the marble distribution at the Hadrian's Villa seems to suggest that the use of sculptural marbles in the Roman world underwent considerable changes around the turn of the 1st and the 2nd century AD. The evidence supporting this hypothesis is briefly summarized in the conclusions.     

Euganean trachytic grinding stones in the Caput Adriae from the Iron Age to the Roman period: Reassessment of the Protohistoric quarries

A group of Euganean trachytic grinding stones from Slovenia and the available data about the same type of artefacts in the whole Caput Adriae are presented. The occurrence of Iron Age saddle querns in Karst and Istria is confirmed, but our study suggests a likely provenance from Mts Cero/Murale instead of Mts Altore/Rocca Pendice, as previously suggested. Este, an important Venetic centre, is just south of Mts Cero/Murale, suggesting its central role in the production and distribution of saddle querns. During the Roman period Euganean trachytes are still used for rotary millstones, but new quarries (Mt Rosso), relatively close to ancient Padua, are exploited. Such shift in the position of millstone quarries most probably reflects the changed geopolitical framework.     

A GEOARCHAEOLOGICAL STUDY OF THE ANCIENT QUARRIES OF SIDI GHEDAMSY ISLAND (MONASTIR,TUNISIA)

Amongst a large number of ancient quarries scattered along the North African coast, those at Sidi Ghedamsy (Monastir, Tunisia) have supplied building stones of Pliocene age. Two lithofacies have been distinguished in the quarry faces: (i) fine sandy limestone, which has been used in the construction of Roman and Arabic monuments; and (ii) porous and coarse limy sandstone, which is of bad quality for construction. Laboratory analysis results confirm that the exploitation of stone in antiquity was well focused on the levels containing the first type. This is confirmed by geotechnical tests, which show that the fine sandy limestone is harder and less porous than the coarse limy sandstone. Extraction of these stones began in the Roman period. The Romans exploited the quarries using steel tools that permitted the extraction of blocks from several levels. In the eighth century, Arabic quarry workers continued the stone extraction using the same technique, but they produced blocks of small and medium size. Statistical measurements have been done on the quarry faces and on the walls of the Ribat in order to understand the degree of conformity between the dimensions of the extracted blocks and those used for building, and ultimately to attempt to date the quarries and the construction of the Ribat.     

PETROGRAPHIC AND ISOTOPIC CHARACTERIZATION OF THE MARBLE OF THE ISLAND OF TINOS (GREECE)*

Most outcrops of good‐quality crystalline marble in Mediterranean countries were exploited in Greek and Roman times. Hence, a wide variety of marble is now found in archaeological excavations. The precise determination of the provenance of a marble object is of great archaeological importance, and is now mostly obtained by coupling the petrographic study of a thin section with the analysis of the C and O stable isotopes, or by stereomicroscopy and EPR. The existing databases are considerable but still insufficient, because our knowledge about and study of ancient Mediterranean quarries remain incomplete. The contribution of this research is to add new petrographic and isotopic data on small quarries on the Greek island of Tinos that were exploited in antiquity. This marble belongs to the same geological horizon; it is quite pure, sometimes dolomitic and characterized by a low‐T, high‐P metamorphism that produced a limited recrystallization (MGS varying from 0.64 to 2.50 mm) on marine limestone protoliths. The petrographic features are quite distinctive: the fabric is strongly lineated and often stressed; and the accessory minerals are ubiquitary quartz, ore minerals, graphite and muscovite. As far as the isotopic data are concerned, δ¹³C_PDB varies from 1.1 to 2.7, and δ¹⁸O_PDB from ?1.7 to ?11.4. Both the features and the data have been compared with those of similar marbles used in antiquity, showing that their combination mirrors the fingerprint of the Tinos marble.     

Variety of Black and White Limestone Tesserae Used in Ancient Mosaics in Slovenia

This study concerns the microfacies characterization of white and black limestone tesserae from selected Roman floor mosaics in Slovenia, with the aim of defining their provenance. We investigated 42 tesserae from 15 different mosaics from the archaeological sites of Ljubljana, Izola, Mo?nje, Ptuj, ?rnomelj and ?entpavel, dated from the first century bc to the fifth century ad . Among the studied tesserae, 13 different microfacies were identified: eight black and five white. The most common were mudstones with ostracods (65% of black tesserae) and wacke‐packstones with miliolids (85% of white tesserae). The majority of the identified facies can be found in the Cretaceous successions of the Dinaric Carbonate Platform in south‐western Slovenia, north‐eastern Italy and south‐eastern Croatia, suggesting a regional or imported origin of the tesserae.     

CARBON AND OXYGEN ISOTOPIC RATIOS: A DATA BASE FOR CLASSICAL GREEK AND ROMAN MARBLE

An isotopic data base of δ¹³C and δ¹⁸O analyses of 528 samples collected from 39 classical Greek and Roman quarries of Turkey, Greece, Italy and Tunisia has been accumulated. The discriminative possibilities of the data base vary from quarry to quarry. Most quarries have a distinctive pattern for either or both variables, but some have more than one grouping. The data also overlap for many quarries preventing a unique provenance assignment. If the alternatives are known so that the total pool of possible sources is reduced, the data base can then discriminate and assign a provenance for most classical marble artifacts.     

Quarries and transportation routes of Angkor monument sandstone blocks

Sandstone blocks are the main construction materials used in the Angkor monuments in Cambodia. However, a thorough study of the quarries has not yet been carried out. We conducted a field investigation of sandstone quarries from the Angkor period at the southeastern foot of Mt. Kulen, which is approximately 35 km northeast of the Angkor monuments. As a result, we discovered more than 50 sandstone quarries. On the basis of the measurements of magnetic susceptibilities and thicknesses (step heights), we found that they were quarried at different times. These four quarrying areas were identified as the quarries D to G inferred by Uchida et al. (2007). In addition we investigated a canal that was identified on satellite images, connecting quarry sites at the foot of Mt. Kulen to the Angkor monuments. The field investigation suggests a high probability that the canal was used for the transportation of sandstone blocks from Mt. Kulen.     

SCIENTIFIC CHARACTERIZATION OF THE POHORJE MARBLES,SLOVENIA

As a former part of the great Roman Empire, Slovenia has many archaeological sites featuring buildings and objects entirely or partly constructed from marble whose provenance is doubtful. In Slovenia, the most probable source of such marble is the Pohorje Mountains. For the purpose of supporting further provenance studies, these marbles are fully scientifically characterized. The techniques used are petrographic and geochemical analysis, stable isotope ratio analysis and EPR spectroscopy. The results show that the Pohorje marbles are highly heterogeneous in both their isotopic and geochemical parameters as well as grain sizes. The parameters of the different Pohorje marble outcrops are compared between themselves and with the parameters of known ancient quarries in the Mediterranean and Austria. The use of a multi‐technique approach with combined parameters allows the best possible discrimination.     

THE NORTHERN COLOSSUS OF MEMNON: NEW SLANTS

Chemical and petrographic studies of the two 720-ton ‘Colossi of Memnon’ located near Luxor, and of Egyptian quartzite quarries indicate that the rear pedestal blocks of the northern statue were quarried at Aswan, while the other, main components of the monuments were quarried near Cairo. Our studies suggest that the rear pedestal blocks of the northern statue were part of the reconstruction project undertaken by Roman emperor Septimius Severus. Our studies of the tilting of the statues further suggest that the rear part of the lower torso of the northern statue was moved when the statue was reconstructed. Part of the present-day tilting of the northern statue probably occurred prior to the reconstruction.     

MINERO‐PETROGRAPHIC AND GEOCHEMICAL CHARACTERIZATION OF ‘GRECO SCRITTO’ MARBLE FROM CAP DE GARDE,NEAR HIPPO REGIUS (ANNABA,ALGERIA)*

This work presents the results of the first mineralogical, petrographical and geochemical characterization of the marble quarried from the Cap de Garde headland, not far from Annaba (Algeria). This site is traditionally held by archaeologists to be the main source of supply of the so‐called ‘greco scritto’ marble, which was much used by the Romans for architectural and decorative–ornamental purposes, locally from the first century bc , and in Rome and central and southern Italy from the late Flavian period until the fourth century ad . The databank relating to the quarried material, created here for the first time, is used to establish the origin of ‘greco scritto’ found in six important Roman cities of North Africa: Hippo Regius and Cuicul (Djemila), in Algeria; Volubilis, in Morocco; Cyrene, in Libya; and Carthage and Utica in Tunisia. The results of this archaeometric study support the hypothesis (already put forward by authors) that the ‘greco scritto’used in the Roman Mediterranean originated from different sites, and suggest the existence of a number of North African quarries, also in the vicinity of Annaba.