minerals Article Archaeometric Classification of Scattered Marble Fragments to Help the Reconstruction of Statues Lluís Casas 1, * , Roberta Di Febo 1 , Julio César Ruiz 2 , Mauro Brilli 3 , Fabrizio Antonelli 4 and Juan Diego Martín-Martín 5 1 Departament de Geologia, Universitat Autònoma de Barcelona (UAB), Edifici C, 08193 Cerdanyola del Vallès, Catalonia, Spain 2 Departament de Ciències de l’Antiguitat i de l’Edat Mitjana, Universitat Autònoma de Barcelona (UAB), Edifici C, 08193 Cerdanyola del Vallès, Catalonia, Spain 3 Istituto di Geologia Ambientale e Geoingegneria (IGAG), Consiglio Nazionale delle Ricerche (CNR), Area della Ricerca di Roma 1, Via Salaria km 29,300, 00015 Montelibretti, Italy 4 LAMA–Laboratorio di Analisi Materiali Antichi, Università Iuav di Venezia, San Polo 2468/B, 30125 Venice, Italy 5 Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), 08028 Barcelona, Catalonia, Spain * Correspondence: lluis.casas@uab.cat Abstract: A multi-technique approach combining petrographic, cathodoluminescence, and stable isotope analyses is commonly used in provenance studies of archaeological marbles. In the present paper, this characterization approach transcends provenance, and it is applied to the reconstruction of fragmented sculptures. The potential of this novel application of archaeometric measurements is illustrated with a case study consisting in 16 scattered marble fragments retrieved from a Roman villa (Els Munts) near Tarraco (presently Northeastern Spain). The samples were grouped taking into account their similarity in quantified parameters such as the cathodoluminescence color clusters and the stable carbon and oxygen isotopic ratios. The results permitted classification of the fragments Citation: Casas, L.; Di Febo, R.; Ruiz, J.C.; into three groups corresponding to three different statues depicting Antinous (7 fragments), Minerva Brilli, M.; Antonelli, F.; Martín-Martín, goddess (4 fragments), and an undetermined character (3 fragments). Two other fragments could not J.D. Archaeometric Classification of be ascribed to any particular statue. The archaeometric grouping provides arguments that can be Scattered Marble Fragments to Help the Reconstruction of Statues. used to confirm or refute archaeological hypotheses of statue reconstructions. Minerals 2022, 12, 1614. https:// doi.org/10.3390/min12121614 Keywords: cathodoluminescence; isotopes; image processing; marble; archaeometry Academic Editor: Adrián Durán Benito Received: 20 November 2022 1. Introduction Accepted: 13 December 2022 In many civilizations, and particularly in those of the classical world, statues were Published: 15 December 2022 considered one of the most valued works of art. Often sculpted in marble or other precious Publisher’s Note: MDPI stays neutral stones, they depicted humans, divinities, animals, and mythological creatures. with regard to jurisdictional claims in The earliest Greek statues were placed in temples and represented gods, and by the published maps and institutional affil- 7th century BCE, kuroi and korai decorated sanctuaries and gravesites. In classical Greece iations. (5th–4th centuries BCE) the use of statues extended to public and private places including agorae and gateways, the divinities remained the most characterized figures. Later, in the Hellenistic period, statues often portrayed the dynastic leaders and ruler cults included rich victory monuments where nonidealized bodies were also represented. Copyright: © 2022 by the authors. In the Roman Republic, divinities were also the most depicted subjects in statues, and Licensee MDPI, Basel, Switzerland. they were usually exhibited in public places. Naturalistic and nonidealized portraits, often This article is an open access article carved as busts, and accompanied with inscriptions were also introduced in public spaces. distributed under the terms and In Late Republic times, the statues embellished public spaces as fora, temples, basilicas, conditions of the Creative Commons theaters, and baths. Wealthy people also decorated with statues their gardens and porticoes Attribution (CC BY) license (https:// in cities and country villas. After the conquest of Magna Graecia and later Greece itself, creativecommons.org/licenses/by/ the Romans tried to emulate Hellenistic architectural environments. In imperial Rome, the 4.0/). Minerals 2022, 12, 1614. https://doi.org/10.3390/min12121614 https://www.mdpi.com/journal/minerals Minerals 2022, 12, 1614 2 of 15 emperor official portraits statues and busts were extensively copied and used to highlight their image as a symbol of power. The number of statues in imperial Rome was a feature that had never been seen before. Pieces from the Classical and Hellenistic past were moved to Rome and often copied and adapted. As a result of the intensive use of stone statues and the durability of the material, it is relatively common to find them in significant archaeological sites. However, it is very rare to find intact pieces. Usually, the bases appear without their corresponding statues. Dispersed and mixed fragments of heads and bodies appear scattered in excavations. Sometimes the statues were even deliberately broken because of iconoclastic expressions. Additionally, the biggest fragments are often found displaced, even reshaped, and reused as building materials. A common problem for archaeologists and restorers is to classify the different fragments and to try to reconstruct art pieces that are in a fragmented status. The classification and reconstruction of fragmented statues is an arduous task usually undertaken by manually checking matching pairs. Digitalization of the fragments through 3D scanning can be helpful to attempt virtual reconstructions and to check virtually different reconstructive hypotheses [1,2] including the addition of missing or incomplete fragments. Artificial intelligence algorithms can also be used to compute automatically the most probable positions of the fragments [3]. These automatic methods often allow the setting of a flexible set of operators by the user that can result in highly plausible reconstructions. However, before attempting any manual or computer-assisted reconstruction, it is crucial to know, with the highest possible certainty, that the fragments under study do really belong to the same object. Several archaeometric approaches have the potential to shed light into this issue, but as far as we know, they have only been rarely used to confirm or refute archaeological reconstruction hypotheses [4]. In the case of marble statues, the common archaeometric characterization techniques include petrography, stable isotope studies, and cathodoluminescence. However, this charac- terization is usually aimed at unveiling the provenance of the marble [5–7], and this essentially to obtain information on the chronology, the importance of the piece, the financial status of the owners, the economic relations, or the ancient commercial routes. Archaeometric characterization is not commonly used to discern the fragments that belong to the different statues retrieved from a given site because often many of them are carved using the same marble variety. For instance, in a provenance study of marbles from the Hadrian’s Villa, the prevalence of Carrara marble was observed [8]. Similarly, in a study of Romain marble sculptures from the National Museum of Carthage [9], nine out of thirteen statues were carved in Pentelic marble. Usually, it is assumed that the archaeometric discrimination between fragments of two statues worked in a same variety of marble is not possible. In this paper, we illustrate this possibility with a set of 16 fragments of marble re- trieved from the Roman villa of Els Munts (12 km from Tarragona, Northeastern Spain), some of them assigned to a portrait of Antinous and others to a statue of Minerva. The common multi-technique archaeometric characterization was applied to all the fragments to infer their provenance. Once established that most of the fragments could belong to a same marble variety, the quantification of the cathodoluminescent (CL) colors and stable isotopes were used to add objective and numeric data to the archaeological discussions and open hypotheses on statue reconstructions. The main goal of the investigation is to find archaeometric evidence to distinguish fragments from different statues and ultimately to determine the identity of the fragments to either the Antinous portrait or the goddess Minerva statues. Recently, this classification approach has been effectively applied to check some re- construction hypotheses of the Forma Urbis Romae [10]. Both CL response and isotopic signature can be sometimes characteristic of a given variety of marble, but there are always slight variations (in CL color, CL intensity, CL distribution, and isotopic ratios). The ap- proach presented here assumes that CL and isotopic measurements from a single carved object should produce more similar CL features and isotopic values compared to fragments from other objects, even in the case of statues carved with the same marble variety. This Minerals 2022, 12, x FOR PEER REVIEW 3 of 16 Minerals 2022, 12, 1614 3 of 15 carved object should produce more similar CL features and isotopic values compared to fragments from other objects, even in the case of statues carved with the same marble hypothesis variety. Thishad been proven hypothesis had beencorrect provenforcorrect physically matching for physically slab fragments matching from the Forma slab fragments from the Urbis map Forma [10].Urbis map [10]. Theofimportance The importance of reconstruction, reconstruction, in the caseinofthe case of frag- fragmented statues and mented statues generally andtype for any generally for any type of sculpture, of sculpture, concerns manyconcerns many aspects of aspects of to significance signifi- archaeologists, cance art to archaeologists, historians, art and historians, historians, museum historians, and museum conservators, suchconservators, such as the as the preservation of the knowl- preservation of the knowledge gathered on the artwork, its functional (e.g., decorative, edge gathered on the artwork, its functional (e.g., decorative, devotional, memorial) and devotional, memorial) and economic contexts or the present-day value of the preserved economic contexts or the present-day value of the preserved object. object. 2.2. Materials andMethods Materials and Methods 2.1. Sampled Materials 2.1. Sampled Materials The sampledmaterials The sampled materialsare are marble marble statues statues andand fragments fragments (Figure (Figure 1) from1) from the Roman villa the Roman known villa known as “Els Munts” (in Altafulla, Catalonia, Northeastern Spain) [11]. This villawas built in as “Els Munts” (in Altafulla, Catalonia, Northeastern Spain) [11]. This villa the was1st century built in theCE1st on a hill CE century 12 km on aeast hill from 12 kmTarraco (presently east from Tarraco Tarragona) along the coast. The (presently Tarragona) alongoutstands villa the coast. for Thethevillasize outstands for the size of thesite of the archaeological archaeological site and the sumptu- and the sumptuousness of its decorative ousness ofDuring elements. its decorative the 2nd elements. centuryDuring CE, itsthe 2nd century splendor wasCE, itspeak, at its splendor wasthe it was at its peak, of Caius residence it was the residence of Caius Valerius Avitus, one of the duumvirs Valerius Avitus, one of the duumvirs of Tarraco. At the end of the 3rd century, of Tarraco. At the enda great fire of the 3rd century, a great fire destroyed most of the villa, although it remained partially destroyed most of the villa, although it remained partially occupied until the 6th or 7th century. occupied until the 6th or 7th century. Abundant material was excavated from the site, Abundant material was excavated from the site, including elements of the decorative program including elements of the decorative program of the building, among this, a large quantity of the building, among this, afree-standing of statues. The better-preserved large quantity of statues. statues have been The better-preserved intensely studied, mainly free-standing statues have been by Koppel [12,13]. intensely studied, mainly by Koppel [12,13]. Figure 1. The sixteen sampled marble fragments retrieved from the “Els Munts” Roman villa. Figure 1. The sixteen sampled marble fragments retrieved from the “Els Munts” Roman villa. Apart from the well-studied statues, many more fragments have remained unstudied Apart from the well-studied statues, many more fragments have remained unstudied in the off-site collections of the Museu Nacional Arqueològic de Tarragona (MNAT) since in the off-site collections of the Museu Nacional Arqueològic de Tarragona (MNAT) since the excavations undertaken in the sixties of the last century. The study of these the excavations undertaken in the sixties of the last century. The study of these unpublished statues is currently being undertaken by one of us (J.C.R.) and some preliminary conclusions have been drawn [14]. Most of these fragments were found in the residential building of the villa around the ambulacrum and the rooms of representation where guests were received. Possibly, the corresponding statues were part of the decorations in these areas. Despite their fragmentary state, it is occasionally possible to identify mythological and divinity representations, mainly of small size and rarely with sizes above the natural size. A total number of 16 marble fragments (Figure 1 and Table 1) were carefully collected from fracture surfaces in the form of tiny chips using a small hammer and a chisel, avoiding Minerals 2022, 12, 1614 4 of 15 weathered material and patinas. All the samples were split into two parts, one to be used for thin-section preparation, the other one to be pulverized for isotopic analysis. In two cases (samples 11 and 12), the sampled fragment was too small to split, and the whole fragment was ground. Table 1. Sampled marble fragments, with indication of museum and excavation references, a short description, the context where they were found, and the year of the finding, along with the most accepted archaeological interpretation about their identity. Archaeological Label MNAT Ref. Excavation Ref. Description Context (Year) Hypothesis 1 45406 - Antinous head RB 1 , cistern (1969) Antinous 2 45406 Antinous torso RB 1 , corridor (1995–1996) Antinous 3 - - Right shoulder unknown (1960–1970) Antinous? Pedestal with right food 4 46589 EM-96-4501-1 RB 1 , room 4500, UE 4501 (1996) Antinous? and animal legs Undetermined RB 1 . Last room in northern 5 - EM-1969 anatomical Antinous? corridor, layer III (1969) fragment (leg?) 6 - EM-96-4601-1 Arm fragment RB 1 . Room 4600, UE 4601 (1996) Antinous? 1. RB Last room in northern 7 - - Forearm fragment? - corridor, layer III (1969) 8 - - Knee fragment unknown (1960–1970) Antinous? Forearm fragment? with 9 - - unknown (1960–1970) - indetermined attribute EM-95-4108- 10 - Puntello fragment RB 1 . Corridor, UE 4108 (1995) - 20bis Right-top part of a torso EM-95-4108- RB 1 . Corridor, UE 4108 (1995) 11 - of a statue with aegis Minerva? 4/EM-96-4310 and Room 4300, UE 4310 (1996) (split in two fragments) Left hand with 12 - EM-95-4108-5 RB 1 . Corridor, UE 4108 (1995) Antinous? undetermined object Right forearm fragment? 13 - EM-95-4102-14 RB 1 . Corridor, UE 4102 (1995) Antinous? includes puntello Fragment of forearm RB 1 ‘Stuccos trench’ (1968) and 14 46558 EM-96-4306-1 and hand with shield Minerva? Room 4300, UE 4310 (1996) (split in two fragments) Statue dressed 15 - EM-96-4511-1 RB 1 , room 4500, UE 4511 (1996) Minerva? in peplos? Body fragment of an Presumably from the RB 1 . 16 - - Minerva? indetermined animal Corridor, UE 4102 (1995) 1 Residential building. The sampling criterion was driven by the macroscopic similarity between the sampled marble fragments and two pieces on display at the Costa dock exhibition facilities of the MNAT. These two pieces were also sampled (samples 1 and 2) and consist of an isolated head and a torso stuck with part of the extremities (Figure 1). The portrait is interpreted to depict Antinous, a Greek youth and favorite of the Roman emperor Hadrian, which was deified after his premature death. This Antinous portrait is the only one reported in Hispania and one of the few found in a private villa. The surfaces of the sampled fragments do not match with the fracture surfaces of the head and body of Antinous and all evidence indicates that the statue was shattered in very many pieces. Minerals 2022, 12, 1614 5 of 15 The only previous provenance study on this statue is from the eighties of the last century and restricted to the head. A Paros origin was suggested for its marble exclusively by petrographic thin-section examination [15]. Unfortunately, no contrastable graphic material is available in the mentioned reference. Therefore, the present study can be considered the first provenance study of the marble fragments from the “Els Munts” villa. Taking into account the exceptional nature of the sculpture repertoire of this villa, some years ago, Pensabene [16] already pointed out the need for a full review of its carved marbles, including the Antinous head. The torso, found in the nineties of the last century, does not connect directly with the head, but considering their characteristics, were already assigned to the same statue by Koppel [12]. However, so far, no archaeometric study has been done to corroborate this adscription. Additionally, after a careful systematic revision of the statues and fragments from the off-site collections of MNAT, we suggest the ascription of seven fragments (labels 3, 4, 5, 6, 8, 12, and 13 in Table 1) to the Antinous statue. This attribution is based on consistent proportions, similar surface finish, and analogous macroscopic aspect of the marble. Another group of sampled marble fragments (those labeled 11, 14, 15, and 16) also share macroscopic features with the portrait of Antinous. However, based on iconographic grounds, this group seems to belong to another statue, perhaps depicting goddess Minerva. One of these fragments, a left forearm and hand with shield (label 14), was arbitrarily interpreted as a part of a gladiator statue supposedly corresponding to the decoration of the baths of the villa [12]. Finally, three more fragments (7, 9, and 10) were also sampled and there is not any archaeological interpretation for them. 2.2. Methods At the Istituto di Geologia Ambientale e Geoingegneria (CNR) of Rome, oxygen and carbon isotopic ratios were determined on all the sampled fragments using a small amount (0.15–0.20 mg) of powdered marble. A Thermo Gasbench II automatic preparation device was used for phosphoric acid digestion at 72 ◦ C and CO2 purification; a Finnigan Delta Plus mass spectrometer measured the 13 C/12 C and 18 O/16 O isotope ratios of the carbon dioxide produced from the digested marble powder. The results were expressed in the usual delta notation, which represents the relative deviation in parts per thousand of the heavy isotope/light isotope ratio of the samples from that of a reference standard. The international standard used was V-PDB for both the oxygen and carbon isotopes. The precision of the analyses was ±0.10‰ (1σ) as observed from repeated analysis of three in-house calcite standards. Petrographic thin-sections were prepared from the largest samples extracted from the sampled fragments. These were characterized petrographically using a polarizing light microscope (OM) (Nikon Eclipse E600 POL, Tokyo, Japan) under plane polarized light (PPL) and cross polarized light (XPL). The thin-sections were also observed under cathodolumi- nescence (CL) microscopy at the Earth Sciences Faculty, Universitat de Barcelona, using CL8200 Mk5-1 equipment (Cambridge Image Technology Ltd., Welwyn Garden City, Hert- fordshire, UK), with operating conditions of 15 kV and a gun current of ~300 µA. Images were obtained with exposures time of 3, 6, and 15 s for all the analyzed areas. Numerically quantifiable petrographic parameters (MGS, MFS) were measured using NIS-Elements, Microscope Imaging Software (Nikon, Tokyo, Japan). The obtained cathodoluminescent images were treated statistically to quantify their color features in order to establish similarities between samples. The CL images were first cropped to isolate large rectangular areas containing only the colors of the CL response of samples (cracks, empty spaces, and adjacent areas to the marble thin-section were avoided). Average pixel values were computed for all of the images. Additionally, pixel clustering was also applied to the cropped images using the CLARA algorithm [17]. After clustering, the images were transformed into a segmented (or simplified) version of them containing only a limited number of different colors (from 1 to 10). The values corresponding to the average pixels and color clusters were numerically expressed as RGB triplets indicating the combination of red (R), green (G), and blue (B). As RGB is an additive color model, white Minerals 2022, 12, 1614 6 of 15 is represented by (255, 255, 255) and black by (0, 0, 0). To represent the color values in a bidimensional plot, the color CIE 1931 xy chromaticity diagram was used. In addition to the quantification of the colors, the size of every CL color cluster was also quantified with a numerical value indicating the corresponding number of pixels of the cluster. 3. Results 3.1. Petrography The petrographic features of all the analyzed marbles are summarized in Table 2. The microscopic study showed calcite marbles with isotropic fabric and, generally, heteroblastic microstructure (sample 5 is the only with a homeoblastic one) forming a mosaic of crystals (Figure 2). See Figure S1 within the Supplementary Materials for illustrative micrographs of all the analyzed samples. Occasionally the crystals define a mortar-like microstructure consisting of larger crystals surrounded by smaller crystals instead of strictly defining a mosaic (sample 3 and, to a lesser extent, sample 7). The maximum grain size (MGS) values are generally above 2 mm. The coarser sample is number 8 with an MGS of 2.64 mm. Only three samples show values below 2 mm (samples 5, 10, and 14) and these would correspond to fine-grained marbles. However, especially in the case of sample 10, the total surface useful for obtaining a thin-section was very small. Therefore, it is not possible to exclude coarser grain-size marbles. Besides MGS, the most common grain size is generally between 0.6 and 1.5 mm (for sample 14 the most common values are between 0.5 and 0.6 mm). The shape of the boundaries between grains are invariably curved and often embayed. Finally, another common feature generally observed in the analyzed samples is the presence of straight mechanical twinning in the crystals in the form of thin twins (type I) and tabular thick twins (type II) [18]. In most of the cases (9 samples out of 14; see Table 2), the petrographic features observed using the optical microscope fit well with those recognized for the Parian marbles (Greece), particularly the variety quarried in the Lakkoi district (Paros-2). Samples 3, 7, 10, and 14 could also probably be associated with Parian marble, but they show some disharmonious attributes. On the one hand, sample 7 and in particular sample 3 exhibit a mosaic microstructure tending to mortar that does not allow ruling out a provenance from Prokonnesos (presently Marmara Island, Turkey); on the other hand, should samples 10 and 14 be really fine-grained, they would be classified as Pentelic (Attica, Greece). Finally, sample 5 is most likely a fine-grained marble with microstructural features compatible with marmor Lunense (presently Carrara, Apuan Alps, Italy), although a provenance from Göktepe (Ephesos, Asia Minor) cannot be excluded. Table 2. List of the main petrographic characteristics and isotopic ratios (V-PDB ‰) correspond- ing to the measured samples. Textural qualifiers are Hom: homogeneous; Het = heterogeneous; Mor = mortar; Mot = mottled; Bo = boundary grains; MGS is maximum grain size; MFS is most frequent grain size range. GBS is grain boundary shape, C = curved or E = embayed. CL is cathodolu- minescence; LL (very low)/L (low)/M (medium). Sample Texture MGS (mm) MFS (mm) GBS CL Intensity CL Texture δ13 C (‰) δ18 O (‰) Hypothesized Provenance 1 Het/Mos 2.08 0.6–1.2 C LL Hom 2.34 −3.14 Paros-2 2 Het/Mos 2.16 0.5–1.5 C LL Hom 2.33 −3.20 Paros-2 3 Het/Mor 2.56 0.7–1.2 E/C LL Hom 2.39 −3.07 Paros-2/Prokonnesos 4 Het/Mos 2.40 0.6–1.0 C/E LL Het/Mot 1.65 −3.43 Paros-2 5 Hom/Mos 1.72 0.7–1.3 C M-L Het 2.07 −3.17 Carrara/Göktepe 61 - 2.00 - - LL Hom 2.18 −3.28 Paros-2 Het/Mos 7 2.40 0.8–1.4 C/E LL Hom 1.91 −3.25 Paros-2/Prokonnesos to Mor 8 Het/Mos 2.64 0.8–1.7 C/E LL Het/Mot 1.26 −3.99 Paros-2 9 Het/Mos 2.16 0.8–1.4 C/E LL Het/Mot 1.92 −3.61 Paros-2 10 1 Het/Mos 1.26 0.5–1.0 C/E LL Het/Mot 2.13 −4.03 Paros-2/Pentelikon? 11 Het/Mos 2.32 0.8–1.2 C/E LL Het 2.36 −3.61 Paros-2 12 2 - - - - - - 2.13 −3.66 Paros-2 13 2 - - - - - - 2.21 −3.52 Paros-2 14 1 Het/Mos 1.28 0.5–0.6 C LL Het/Bo 1.93 −4.68 Paros-2/Pentelikon? 15 Het/Mos 2.56 0.7–1.7 C LL Het/Bo 2.14 −4.89 Paros-2 16 Het/Mos 2.48 0.6–1.5 C/E LL Het 1.26 −3.60 Paros-2 1 The area cut in the thin-section is not (6) or may not (10, 14) be statistically significant; 2 No thin-section was cut. Minerals 2022, 12, 1614 7 of 15 Minerals 2022, 12, x FOR PEER REVIEW 7 of 16 Figure 2. Petrographic images of three representative sampled marble fragments ncluding XPL (top) Figure 2. Petrographic images of three representative sampled marble fragments ncluding XPL and CL (bottom) micrographs of the same areas using an exposure time of 15 s. (a) sample 1; (b) (top) and sample 5; CL (bottom) (c) sample 14. micrographs of the same areas using an exposure time of 15 s. (a) sample 1; Minerals 2022, 12, x FOR PEER REVIEW 8 of 16 (b) sample 5; (c) sample 14. Table 2. List of the main petrographic characteristics and isotopic ratios (V-PDB ‰) corresponding 3.2. Stable to the Isotopes measured samples. Textural qualifiers are Hom: homogeneous; Het = heterogeneous; Mor = mortar; Mot = mottled; Bo = boundary grains; MGS is maximum 13 grain size; MFS is most frequent similar Theand range results from of the 1.26‰ to measured 2.39 C stable ‰andforOcarbon isotope(δratios C) and from −3.07‰ corresponding toto 4.89 the 16 ‰ for sampled grain size range. GBS is grain boundary shape, C = curved or E = embayed. CL is cathodolumines- oxygen marble (δ 18 O). fragments are summarized cence; LL (very low)/L (low)/M (medium). in Table 2. The isotopic values are rather similar and range All thetoisotopic from 1.26‰ 2.39 ‰values for carbon (δ13 C) and are plotted in afrom diagram −3.07‰ in which to 4.89the ‰isotopic (δ18ofO). fields for oxygen the MGS main MFS medium/coarse-grained CL classical white δ 13C marbles δ 18O [19] are Hypothesized represented together with a Sample Texture All the isotopic values are plotted in a diagram in which the isotopic fields of the main GBS CL Texture (mm) (mm) Intensity (‰) (‰) Provenance relevant Hispanic marble after [20] (Figure 3). Considering the MGS medium/coarse-grained classical white marbles [19] are represented together with a relevant values, all the sam- 1 Het/Mos 2.08 0.6–1.2 C LL Hom 2.34 −3.14 Paros-2 ples (except Hispanic 5, 10,after marble and[20] 14) (Figure can be unquestionably 3). Considering represented the MGS values, in thisall diagram. Almost the samples all (except 2 Het/Mos 2.16 0.5–1.5 C LL Hom 2.33 −3.20 Paros-2 the 5,2.56 samples 10, and lie in 14) can E/C an area where be unquestionably five different represented fields overlap; these are Aphrodisias, Paros- 3 Het/Mor 0.7–1.2 LL Hom 2.39 in −3.07 this diagram. Almost all the samples lie Paros-2/Prokonnesos 4 Het/Mos in2, Prokonnesos-1, an 2.40 area where 0.6–1.0 five C/E Naxos, andfields different LL Hispanic Macael overlap; these Het/Mot 1.65 −3.43 marbles. are However, Paros-2, Aphrodisias, an Aphrodisian Paros-2 and Prokonnesos-1, Naxian Naxos, origin can be certainly ruled out by considering the petrographic features de- be 5 Hom/Mos 1.72 and 0.7–1.3HispanicC Macael M-Lmarbles. HetHowever,2.07 an−3.17 Aphrodisian and Naxian origin can Carrara/Göktepe 61 - scribed certainly 2.00 above. ruled - out -by considering LL the Hompetrographic 2.18 features −3.28 described above. Paros-2 7 Het/Mos to Mor 2.40 0.8–1.4 C/E LL Hom 1.91 −3.25 Paros-2/Prokonnesos 8 Het/Mos 2.64 0.8–1.7 C/E LL Het/Mot 1.26 −3.99 Paros-2 9 Het/Mos 2.16 0.8–1.4 C/E LL Het/Mot 1.92 −3.61 Paros-2 10 1 Het/Mos 1.26 0.5–1.0 C/E LL Het/Mot 2.13 −4.03 Paros-2/Pentelikon? 11 Het/Mos 2.32 0.8–1.2 C/E LL Het 2.36 −3.61 Paros-2 12 2 - - - - - - 2.13 −3.66 Paros-2 13 2 - - - - - - 2.21 −3.52 Paros-2 14 1 Het/Mos 1.28 0.5–0.6 C LL Het/Bo 1.93 −4.68 Paros-2/Pentelikon? 15 Het/Mos 2.56 0.7–1.7 C LL Het/Bo 2.14 −4.89 Paros-2 16 Het/Mos 2.48 0.6–1.5 C/E LL Het 1.26 −3.60 Paros-2 1The area cut in the thin-section is not (6) or may not (10, 14) be statistically significant; 2 No thin- section was cut. 3.2. Stable Isotopes The results of the measured stable C and O isotope ratios corresponding to the 16 sampled marble fragments are summarized in Table 2. The isotopic values are rather Figure3.3.Isotopic Figure Isotopicresults resultsfrom fromthe theanalyzed analyzedsamples samplesplot plotwith withthe theisotopic isotopicreference referenceisotopic isotopic fields fields for for medium/coarse-grained classical marbles from [19]. Macael reference field from [20] is also medium/coarse-grained classical marbles from [19]. Macael reference field from [20] is also included. in- cluded. In an inset plot, samples with MGS < 2 (red dots) are also represented with respect to the In an inset plot, samples with MGS < 2 (red dots) are also represented with respect to the fine-grained fine-grained isotopic diagram proposed by [19]. isotopic diagram proposed by [19]. Strictly speaking, samples 14 and 15 are actually outside the Paros-2 field and sam- ples 8 and 16 are outside the Macael domain. Plotting the three samples with MGS < 2 mm in the isotopic diagram proposed by [19] for fine-grained classical marbles, they appear in an area covered by many isotopic Minerals 2022, 12, 1614 8 of 15 Strictly speaking, samples 14 and 15 are actually outside the Paros-2 field and samples 8 and 16 are outside the Macael domain. Plotting the three samples with MGS < 2 mm in the isotopic diagram proposed by [19] for fine-grained classical marbles, they appear in an area covered by many isotopic fields, including those corresponding to the marbles of Carrara, Göktepe, Paros, and Pentelikon. 3.3. Cathodoluminescence 3.3.1. CL Facies The CL signal measured in petrographic thin-sections is commonly described qualita- tively in terms of color, intensity, and homogeneity [20]. In general, all the studied samples show a very low intensity cathodoluminescence (CL) with blue/violet hue (see Table 2 and Figure 2a), the only exception is sample 5. In contrast with the other samples, sample 5 ex- hibits an orange medium-intensity CL with some small patches of very low blue/violet hue (Figure 2b). See Figure S2 within the Supplementary Materials for illustrative micrographs of all the analyzed samples viewed under the CL microscope. Regarding the distribution of the CL, it varies from relatively homogeneous (samples 1, 2, 3, 6, and 7) to clearly heterogeneous (samples 4, 5, 8, 9, 10, 11, and 14). Specifically, for the medium-intensity CL of sample 5, the orange CL surrounds certain relict crystals bearing almost no CL signal or very low violet (Figure 2b). Similarly, for some samples, such as 11, 14, and 15, the orange CL isolates crystals of very low CL but in contrast, the orange areas are marginal compared with the grains of very low CL (Figure 2c). Finally, other samples, such as 4, 8, and 10, the areas of orange CL are even scarcer and often limited to small veins. It is known that for marbles and limestones, the low wavelength CL emission (blue/violet) is due to intrinsic luminescence centers, mainly lattice imperfections [21]. In contrast, the higher wavelength emission (orange/red) is due to extrinsic luminescence centers due to the presence of CL-activator impurities, mainly Mn2+ replacing Ca2+ in calcite [22]. However, the role of impurities is very complex as there are other reported activator ele- ments as well as inhibitors, and they can interact, thus modifying the overall luminescence response [23,24]. Considering the predominance of the intrinsic CL response for most of the samples (except sample 5), from the marble provenances suggested by the isotopic values (Figure 3), the Naxian provenance can be definitely excluded because its archaeological marbles belong to the orange CL family [25,26]. The Hispanic provenance (Macael) is also implausible because its rare lithotypes with relict grains of low-intensity CL always exhibit very high intensity orange/yellow CL limits [27]. The other three suggested provenances (Aphrodisias, Paros-2, and Prokonnesos-1) are indeed among the blue CL family, but it is difficult to decide which is the most plausible origin. On the one hand, these three marbles generally present a homogeneously blue/violet CL without orange CL patches. However, according to the results shown in [28], Paros-2 is the only marble that appears to present a certain CL heterogeneity but with an overall medium CL intensity and not low intensity. The fine-grained samples studied (5, 10, and 14) are among those with clearly heteroge- neous CL, which again complicates their identification with known CL facies. Nevertheless, some classical fine-grained marbles that commonly display homogeneous low-intensity CL are also known to occasionally exhibit combinations of low-intensity (dark or blue) and medium-intensity (orange) domains, such as Göktepe, where small orange domains can sometimes appear [29] and Carrara, where small dark domains can infrequently appear [30]. Another well-known fine-grained marble, Pentelikon, exhibits a heterogeneous CL but always including very high-intensity orange CL domains [28,31] not observed in any of the analyzed samples. This questions the ascription of samples 10 and 14 to a Pentelic marble. 3.3.2. CL Color Clustering The CL images treated with the CLARA algorithm turned into simplified versions of them bearing a limited number of colors. The algorithm was set to allow ten as the maximum number of colors. However, most of the simplified images contain only two colors (see Table 3). The images corresponding to samples 4, 8, 9, and 16 contain three Minerals 2022, 12, 1614 9 of 15 color clusters, and sample 11 is the exception to this reduced number of color clusters as its corresponding image contains eight different colors (although actually three of them with a rather low number of pixels). See Figure S3 within the Supplementary Materials for the cropped CL image areas and their corresponding simplified versions. Table 3. RGB color values for the analyzed CL images including the average pixel and the color clusters for the images treated with the CLARA algorithm; the area percentages of the color clusters are also indicated. The actual colors are also reproduced. Average Pixel Color Clusters Sample Color Number of Clusters R G B % R G B Color 55 22 28 62 1 28 34 67 2 45 32 38 72 62 23 31 77 2 29 38 82 2 38 37 43 91 75 23 29 65 3 27 32 68 2 25 38 43 81 47 46 34 58 4 42 33 59 3 37 24 25 55 15 70 46 70 70 135 67 64 5 113 60 60 2 30 55 35 62 62 24 31 59 6 30 35 63 2 38 35 42 70 65 20 35 74 7 14 28 66 2 35 11 25 62 42 56 43 63 8 58 44 66 3 33 79 52 71 25 28 29 60 43 42 30 52 9 58 41 60 3 43 64 45 64 14 92 59 80 65 45 40 60 10 35 31 52 2 35 27 27 51 32 28 26 50 22 23 19 42 12 35 32 54 12 36 28 43 11 34 26 47 8 10 46 29 47 5 62 40 52 4 43 42 60 3 76 49 56 62 87 51 55 14 55 39 55 2 38 31 31 57 63 71 49 70 15 49 40 60 2 37 30 31 59 51 57 48 67 16 34 31 57 3 36 42 32 57 12 25 26 57 The RGB values obtained were converted into CIE XYZ values. These latter values characteristically have very low Y (luminance) values. In fact, except the most reddish color cluster of sample 5, luminances are always below 5 (in the 0–100 range). The XYZ values were then converted into xy values to plot them on a bidimensional luminance-independent chromaticity diagram [32]. The results are shown in Figure 4. The values corresponding to the color clusters align roughly in a slightly curved line within the chromaticity plot, in a color area that ranges from the blue-violet color region toward the purple, yellowish pink, and orange regions. The corresponding average pixels for all the samples also align within the same curved line. Minerals 2022, Minerals 2022, 12, 12, 1614 x FOR PEER REVIEW 11 10 of 16 of 15 Figure 4. Position Figure 4. Position of of the the color color clusters clusters in in an an xy xy chromaticity chromaticity diagram with indication diagram with indication of of the the corre- corre- sponding sponding sample. The position The position ofof the average pixels for average pixels for allall the images images is also represented in red. Inset: Inset: A colored complete chromaticity diagram with indication of the color color cluster cluster position position (black (black dots) and dots) and the the rectangle rectangle corresponding corresponding to to the thepart partof ofthe thediagram diagramdepicted depictedininthe themain mainfigure. figure. 4. 4. Discussion Discussion The The first first requirement requirementto tostart startaapossible possiblereconstruction reconstructionofofa afragmented fragmentedstatuestatueis isobvi- ob- ously that all the fragments considered belong to the same type of marble. viously that all the fragments considered belong to the same type of marble. The petro- The petrographic results graphicindicate results that mostthat indicate of the mostanalyzed samples indeed of the analyzed samplesshowindeed similar showmicrostructural similar micro- features (isotropic fabric, curved to embayed grain boundaries, structural features (isotropic fabric, curved to embayed grain boundaries, and more or less andcompara- more or ble less comparable MGS and MFS values). The CL response is also similar for most ofwith MGS and MFS values). The CL response is also similar for most of the samples, the predominance of low-intensity blue/violet colors with a secondary role (sometimes almost samples, with predominance of low-intensity blue/violet colors with a secondary role inexistent) of orange CL color in some small areas. Most of the sampled marbles were (sometimes almost inexistent) of orange CL color in some small areas. Most of the sampled identified as the medium-grained marble Paros-2. However, samples 3 and 7 are not so marbles were identified as the medium-grained marble Paros-2. However, samples 3 and straightforward identified as Paros-2, and an origin from Prokonnesos is also plausible. 7 are not so straightforward identified as Paros-2, and an origin from Prokonnesos is also Additionally, samples 10 and 14 appear as fine-grained marbles petrographically consistent plausible. Additionally, samples 10 and 14 appear as fine-grained marbles petrograph- with Pentelikon origin, although the observed CL casts doubt on such interpretation. How- ically consistent with Pentelikon origin, although the observed CL casts doubt on such ever, the small area cut in the thin-section of these two samples might not be statistically interpretation. However, the small area cut in the thin-section of these two samples might significant, if both marbles were actually medium-grained they would also be classified as not be statistically significant, if both marbles were actually medium-grained they would Paros-2. In contrast, there is no doubt on the fine-grained condition of the homeoblastic also be classified as Paros-2. In contrast, there is no doubt on the fine-grained condition of marble from sample 5, and it definitely cannot be classified as Paros-2. Its petrographic the homeoblastic marble from sample 5, and it definitely cannot be classified as Paros-2. characteristics and the predominance of medium-intensity orange CL with low-intensity Its petrographic blue CL patches make characteristics Carrara (orand the predominance Göktepe) of medium-intensity plausible adscriptions. Furthermore, orange CL it should with low-intensity blue CL patches make Carrara (or Göktepe) be noted that the volumes of samples labeled 12 and 13 did not permit cutting them plausible adscriptions. Furthermore, as thin-sections. it should be noted that the volumes of samples labeled 12 and 13 did not permitApart fromthem cutting sample as thin-sections. 5 (and with some doubts on samples 3, 7, 10, and 14) it is reasonable Apart from sample to undertake a classification 5 (and with of the some doubts samples accordingon samples to their CL3, 7, 10, and 14) similarity it is reason- to assign them able to undertake a classification of the samples according to their to different statues. In the reconstruction of the slabs from the Forma Urbis Romae CL similarity to assign [10], a them tokind similar different statues. In was of classification the reconstruction performed by of the slabsthe measuring from the Forma similarity Urbis marble between Romae [10], a similar kind of classification was performed by measuring the fragments based on averaged CL colors. In the present case, the averaged pixels concentrate similarity between marble in a veryfragments short segmentbased andon averaged CL colors. the discussion on theInsimilarity the present case, the between averaged samples haspixels been concentrateusing articulated in a very short segment essentially the resultsand thepixel from discussion on the clustering, and similarity between the averaged pixelsamples values hasonly are beenconsidered articulatedtangentially. using essentially the results from pixel clustering, and the averaged pixel values are only considered tangentially. Minerals 2022, 12, x FOR PEER REVIEW 12 of 16 Minerals 2022, 12, 1614 11 of 15 Only two samples are undisputedly assigned to a given statue (samples 1 and 2). These Only two samples two samples belongareto undisputedly the head andassigned torso oftothe a given statue so-called (samplesstatue, Antinous 1 and 2). on These dis- play at the Costa dock exhibition facilities of the MNAT. Both samples exhibit similaratav- two samples belong to the head and torso of the so-called Antinous statue, on display the Costa dock exhibition facilities of the MNAT. Both samples exhibit similar average colors erage colors with low x and y chromaticity coordinates and their corresponding seg- with low x and y chromaticity coordinates and their corresponding segmented images mented images contain only two color clusters, again with similar chromatic coordinates contain only two color clusters, again with similar chromatic coordinates (Figure 5). In fact, (Figure 5). In fact, one of the color clusters is essentially the same for both samples. Apart one of the color clusters is essentially the same for both samples. Apart from these two from these two samples, there are three other samples (3, 6, and 7) with similar chromatic samples, there are three other samples (3, 6, and 7) with similar chromatic values (Figure 5, values (Figure 5, red circles). All these samples are characterized by an almost complete red circles). All these samples are characterized by an almost complete absence of orange absence of orange patches of CL and their corresponding fragments could belong to the patches of CL and their corresponding fragments could belong to the same statue, and the same statue, and the others would not be part of the Antinous statue. others would not be part of the Antinous statue. Thecolor Figure5.5.The Figure colorclusters clustersposition position(open (opendots) dots)asasdepicted depictedininFigure Figure4,4,but butnow nowgrouped groupedand and zoomed zoomed ininthree threesets (red, sets green, (red, andand green, yellow) to highlight yellow) the chromatic to highlight similarities the chromatic between similarities the CL between the response of the different samples. The size of the open dots in the zoomed sets has been CL response of the different samples. The size of the open dots in the zoomed sets has been made made pro- portional to thetosize proportional the of theofcorresponding size colorcolor the corresponding cluster. cluster. The Theindividuation individuationofofsamples sampleswith withabsence absenceofoforange orangeCL CLpatches patcheswas wasalready alreadyrather rather noticeable without the use of tools to quantify the CL colors. For the rest noticeable without the use of tools to quantify the CL colors. For the rest of the samples, of the samples, a qualitative classification a qualitative classificationwould would notnotproduce produce straightforward straightforward results resultsand andquantification quantification appears appearstoto bebemore morenecessary. necessary. OneOneof the samples of the samples(14)(14) comes fromfrom comes a fragment a fragmentof forearm of fore- and armhand with shield—this and hand with shield—thissuggests a possible suggests Minerva a possible Minervastatue. The corresponding statue. The corresponding ca- cathodoluminescence thodoluminescence facies facies for for thisthis sample sample contain contain bluish bluish CLCL relict-grains relict-grains surroundedbyby surrounded moreintense more intenseorange orangeCL CLareas areas(Figure (Figure2c). 2c).AAway waytotoselect selectother othersimilar similarsamples sampleswouldwouldbebe to focus on the bluish relicts to focus on the bluish relicts using the color clusters from the segmented the color clusters from the segmented images. images. There Thereare three are other three samples other samples(10,(10, 11,11, and 15)15) and thatthat have approximately have approximately a blue color a blue cluster color located cluster lo- at the cated atsame coordinates the same (Figure coordinates 5, green (Figure circles). 5, green TheThe circles). corresponding corresponding fragments fragments could thus could belong thus to the belong statue to the depicting, statue depicting,presumably, presumably, Minerva. Minerva. Fromthe From theremaining remainingsamples, samples, aa group of of three three(4, (4,8,8,and and16)16)emerge. emerge.For Forthis group, this group,the color classification produced three different clusters and again they the color classification produced three different clusters and again they share coordinatesshare coordinates for Minerals 2022, 12, x FOR PEER REVIEW 13 of 16 Minerals 2022, 12, 1614 12 of 15 for the corresponding blue cluster and exhibit a certain affinity regarding the other two the corresponding blue cluster and exhibit a certain affinity regarding the other two color color clusters (Figure 5, yellow circles). Therefore, the three samples could hypothetically clusters (Figure 5, yellow circles). Therefore, the three samples could hypothetically be be part of the same statue. Finally, the CL features of sample 9 (and obviously also sample part of the same statue. Finally, the CL features of sample 9 (and obviously also sample 5) 5) remain ungrouped and this lack of affinity with other samples suggests that they are remain ungrouped and this lack of affinity with other samples suggests that they are not not part of any of the three statues. This inference was already clear for sample 5 because part of any of the three statues. This inference was already clear for sample 5 because petrographicallyititwas petrographically wasunquestionably unquestionablyassigned assignedtotoaadifferent differenttype typeofofmarble. marble. It is worth noting that the isotopic data support the suggested It is worth noting that the isotopic data support the suggested classification of classification ofthethe analyzedfragments analyzed fragmentsin inthree threegroups groups(Figure(Figure6). 6).The Thesamples samplesof ofAntinous’ Antinous’fragments fragments(1, (1,2)2) exhibit the highest isotopic ratios 18(δ 18O and 13 δ 13C) and group together with the samples exhibit the highest isotopic ratios (δ O and δ C) and group together with the samples that thatalso are areattributed also attributed to thistosculpture, this sculpture,shownshownin the in the upper-left upper-left cornercorner of the of theFragments plot. plot. Frag- ments 12 and 13, which could not be analyzed by cathodoluminescence, 12 and 13, which could not be analyzed by cathodoluminescence, also archaeologically also archaeolog- ically attributed attributed to the to the Antinous Antinous statue,statue, locate locate reasonably reasonably close close to thistogroup this group of samples of samples and and therefore therefore the archaeological the archaeological attribution attribution is alsoissupported also supported archaeometrically. archaeometrically. The frag- The fragment ment that is that is seemingly seemingly part ofpart of a Minerva a Minerva statuestatue exhibits exhibits lowerlower δ18 O δ 18O ratios that align with ratios that align with the the other other threethree fragments fragments associated associated to this to this statue, statue, plotting plotting within within a narrowband a narrow δ13CC bandofofδ13 values(green values (greendotsdotsin inFigure Figure6). 6).The Thethird thirdgroup groupof ofsamples samplesthat thatemerged emergedaccording accordingto tothe the classification obtained from the CL analyses (4, 8, and 16) classification obtained from the CL analyses (4, 8, and 16) also appears grouped within also appears grouped within theisotopic the isotopicplot plotexhibiting exhibitingthe thelowest lowestδδ1313C C values values (yellow (yellow dots dots in in Figure Figure6).6). Finally, Finally,thethe isotopicratios isotopic ratiosof ofthe theisolated isolatedsamples samples99and and55appear appearratherratherclose closeto tothe theratios ratiosproduced produced bythe by thesamples samplesattributed attributedto tothetheAntinous. Antinous.However, However,aahypothetical hypotheticalconnection connectionof ofthese these twofragments two fragmentstotothe the Antinous Antinous statue statue appears appears almost almost certainly certainly impossible impossible for sample for sample 5 and5 and rather rather unlikely unlikely for sample for sample 9. On the9. On onethe oneboth hand, hand, both samples samples exhibitvisible exhibit clearly clearlyorange visible orange (or rather(or ratherfor purple purple sample for9)sample CL patches 9) CLthatpatches that are completely are completely absent in absent in samples samples attributed attributed to the Antinous to thestatue; Antinous on thestatue; otheronhand, the other samplehand,5 issample 5 is petrographically petrographically different different from the from theattributed samples samples attributed to this statue. to this statue. Figure6.6.Detail Figure Detailofofthe theisotopic isotopic results results shown shown in Figure in Figure 3, here 3, here coloring coloring the samples the samples according according to to dis- discussed attributions. Black dots correspond to samples of fragments not linked to any other cussed attributions. Black dots correspond to samples of fragments not linked to any other fragment. frag- ment. 5. Conclusions 5. Conclusions The archaeometric provenance study of the 16 studied marble fragments points to Themarble a shared archaeometric variety provenance study for 11 of them, of the most 16 studied probably marble Paros-2. fragments four Additionally, points to a other shared marble samples (labeledvariety forand 3, 7, 10, 11 of 14)them, mightmost also probably have this Paros-2. Additionally, same provenance fourshow- despite other samples ing some(labeled unusual3,characteristics 7, 10, and 14) might for a also havemarble Paros-2 this same (theprovenance despite showing mortar microstructures of samples 3 and 7characteristics some unusual suggest alternatively an origin for a Paros-2 from (the marble Prokonnesos; samples 10 andof mortar microstructures 14samples exhibit lower 3 andgrain-size 7 suggest than expected). alternatively anOne of the origin fromstudied marble fragments Prokonnesos; samples 10 (labeled and 145) is certainly exhibit lower not a Paros-2 grain-size marble than and Carrara expected). One of(or theGöktepe) appearsfragments studied marble as the most reasonable (labeled provenance. 5) is certainly not a Paros-2 marble and Carrara (or Göktepe) appears as the most reasonable provenance. Minerals 2022, 12, 1614 13 of 15 In addition to their contribution in the multi-technique approach commonly used in provenance studies, the combination of isotopic and cathodoluminescence measurements has proven to be a successful approach to classify marbles of a given variety into groups to be correlated with different statues. The presented approach brings archaeometric arguments that can contribute to confirm or refute archaeological hypotheses of statue reconstructions. Most of the 16 analyzed fragments that were included in this case study could be archaeometrically grouped into three sets attributed to statues depicting young Antinous (7 fragments), Minerva goddess (4 fragments), and an indetermined character (3 fragments). Two fragments were not assigned to any set and they would belong, separately, to other statues. The archaeometric study confirmed that the Antinous head (label 1) and the torso (label 2) are indeed part of a same statue along with most of the fragments initially ascribed to it and additionally fragments labeled 7 and 10. However, some doubts remain for these two fragments and from the petrographic point of view, on the true adscription to Paros-2 marble and therefore also to the Antinous statue. From the fragments initially ascribed to the Antinous, only the fragments labeled 5, 4, and 8 were finally not attributed to it. The last two, along with fragment 16 (initially related to the Minerva statue), were considered to be part of a different statue. Concerning fragment 5, CL (and petrographic) data strongly suggests that is made of a different type of marble and, together with sample labeled 9, are the only two fragments that could not be linked to any other fragment. From the archaeological point of view, considering the importance of the Antinous statue, to group the fragments that can be attributed to it constitutes a substantial achieve- ment. The statue is the only known representation of the young Bithynian in Hispania, highlighting the singularity of the decorative program of the Els Munts villa. It is also one of the few Antinous statues with preserved head, torso, and part of the extremities. For most of the known models, only the head has been preserved, and only a few include the torso [33]. Moreover, the approach presented represents a first step to undertake a systematic archaeometric classification of the scattered marble fragments retrieved from the Els Munts villa. The work could be extended to many other fragments from the same site, contributing to reveal more data about the richness and the predominant iconography that decorated this villa, near Roman Tarraco. The innovative use of CL and isotopic analyses to reconstruct fragmented sculptures or other artwork should be extended to other archaeological sites. This would assess the reliability of the method, and it could be established as a regular approach for sculpture reconstruction, in addition to the already common contribution of these techniques to marble provenance determination. Supplementary Materials: The following supporting information can be downloaded at: https://www. mdpi.com/article/10.3390/min12121614/s1, Figure S1: Illustrative micrographs of all the analyzed samples observed in XPL. Figure S2: Illustrative micrographs of all the analyzed samples viewed under the CL microscope using an exposure time of 15 s. Figure S3: Cropped CL image areas (exposure time: 15 s) and their corresponding simplified versions obtained after application of the CLARA algorithm. Author Contributions: Conceptualization, L.C., R.D.F. and J.C.R.; sample selection, J.C.R.; sampling, L.C., R.D.F. and J.C.R.; petrography, R.D.F. and F.A.; isotopic measurements, M.B.; cathodolumi- nescence (CL) measurements, L.C., R.D.F. and J.D.M.-M.; CL color clustering and quantification, L.C.; writing—original draft preparation, L.C., R.D.F. and J.C.R.; writing—review and editing, L.C., R.D.F., J.C.R., M.B., F.A. and J.D.M.-M. All authors have read and agreed to the published version of the manuscript. Funding: This research is partially funded by the Spanish Ministry of Science and Innovation, grant numbers PID2019-104120GB-I00, PID2021-122467NB-C22, and PID2021-122879OB-I00. Data Availability Statement: Most of the data presented in this study have been made publicly available within the Supplementary Materials section. Any other data are available on request from the corresponding author. Minerals 2022, 12, 1614 14 of 15 Acknowledgments: Mònica Borrell, Montserrat Perramon, and Josep Anton Remolà, from the Museu Nacional Arqueològic de Tarragona (MNAT) museum are recognized for granting permission to sample the studied marbles. We are thankful to Lorenzo Lazzarini for providing advice on petrographic descriptions and interpretations. Marc Anglisano is acknowledged for providing support on image-analysis tools. Conflicts of Interest: The authors declare no conflict of interest. References 1. Fazio, L.; lo Brutto, M.; Gonizzi Barsanti, S.; Malatesta, S.G. The Virtual Reconstruction of the Aesculapius and Hygeia Statues from the Sanctuary of Isis in Lilybaeum: Methods and Tools for Ancient Sculptures’ Enhancement. Appl. Sci. 2022, 12, 3569. [CrossRef] 2. Patay-Horváth, A. The Virtual 3D Reconstruction of the East Pediment of the Temple of Zeus at Olympia an Old Puzzle of Classical Archaeology in the Light of Recent Technologies. Digit. Appl. Archaeol. Cult. 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