The origin of the tin used for the production of bronze in the Eurasian Bronze Age is still one of the mysteries in prehistoric archaeology. In the past, numerous studies were carried out on archaeological bronze and tin objects with the aim of determining the sources of tin, but all failed to find suitable fingerprints. In this paper we investigate a set of 27 tin ingots from well-known sites in the eastern Mediterranean Sea (Mochlos, Uluburun, Hishuley Carmel, Kfar Samir south, Haifa) that had been the subject of previous archaeological and archaeometallurgical research. By using a combined approach of tin and lead isotopes together with trace elements it is possible to narrow down the potential sources of tin for the first time. The strongly radiogenic composition of lead in the tin ingots from Israel allows the calculation of a geological model age of the parental tin ores of 291 ± 17 Ma. This theoretical formation age excludes Anatolian, central Asian and Egyptian tin deposits as tin sources since they formed either much earlier or later. On the other hand, European tin deposits of the Variscan orogeny agree well with this time span so that an origin from European deposits is suggested. With the help of the tin isotope composition and the trace elements of the objects it is further possible to exclude many tin resources from the European continent and, considering the current state of knowledge and the available data, to conclude that Cornish tin mines are the most likely suppliers for the 13 th –12 th centuries tin ingots from Israel. Even though a different provenance seems to be suggested for the tin from Mochlos and Uluburun by the actual data, these findings are of great importance for the archaeological interpretation of the trade routes and the circulation of tin during the Late Bronze Age. They demonstrate that the trade networks between the eastern Mediterranean and some place in the east that are assumed for the first half of the 2 nd millennium BCE (as indicated by textual evidence from Kültepe/Kaneš and Mari) did not exist in the same way towards the last quarter of the millennium.

Funding: The authors would like to acknowledge funding received for this project through the European Research Council (ERC Advanced Grant Project BRONZEAGETIN, G.A. no. 323861 to EP). We further acknowledge financial support by Deutsche Forschungsgemeinschaft (DFG) within the funding programme Open Access Publishing, by the Baden-Württemberg Ministry of Science, Research and the Arts and by Ruprecht-Karls-Universität Heidelberg.

In addition to these 45 raw products, another ten tin ingots exist from an off-shore site near Kfar Samir in Israel (called Kfar Samir south). They are also thought to belong to the LBA, and to date from ca. 14 th –13 th century BCE [ 25 ; 27 ; 34 ]. They were salvaged together with Egyptian stone anchors, bronze objects, a bronze sickle sword and five lead ingots during an underwater survey of a shipwreck just 900 metres north of the Hishuley Carmel and 550 metres south of the ‘Haifa’ site ( Fig 1 ). As with the anchors, some of the ingots have inscriptions. The cargo assemblage of this wreck is assumed to be of Egyptian provenance [ 34 ], whereas the Hishuley Carmel objects may be associated with Cyprus or the Syro-Palestinian coast [ 24 , 35 ]. In summary, presently some 215 tin ingots weighing almost one and a half tons are known from BA or presumed BA contexts. In this paper we investigate this material group with the most modern scientific facilities in order to elucidate their history and the provenance of the tin.

(a) Tin ingots from Hishuley Carmel, part of them with Cypro-Minoan marks; numbering corresponds to the original sample designation in Table 3 . (b) Three out of 30 tin ingots from Haifa with Cypro-Minoan inscriptions with their original label from the literature. Scale applies to all ingots on the figure (photos: E. Galili, Fig 4A modified and reprinted from [ 26 ] under a CC BY license, with permission from the International Journal of Nautical Archaeology, original copyright 2013).

The latter also applies to a group of 15 tin ingots recovered in four campaigns from an alleged shipwreck at the coast of Hishuley Carmel, Israel (Figs 1 and 4A ), together with two oxhide copper ingots and several stone anchors [ 23 – 27 ]. Because the archaeological context was missing, the exact dating of the finds is uncertain, but ‘Cypro-Minoan’ symbols inscribed on the surface of several ingots suggest a LBA date of around 1300 BCE [ 23 – 24 ; 26 ]. For the same reason, Maddin et al. [ 21 ] and Stech-Wheeler et al. [ 28 ] assigned two rectangular tin ingots found off the Israeli coast near Haifa to the LBA ( Fig 4B , 8251 and 8252). Their hypothesis was questioned by Artzy [ 29 ], however, who reported on two very similar ingots from Israel (in the literature the place where they were found is mistakenly called Dor or Atlit) with ‘Cypro-Minoan’ inscriptions ( Fig 4B , CMS 6). The upper surface of one of the ingots carries the conjectured head of Arethusa (a Greek fountain goddess); therefore, in her opinion, all four objects should be dated to the 5 th century BCE. However, careful inspection on the Arethusa head by one of the authors (EG) suggested that this image is a random metal spill and was not produced on purpose. In addition, recent investigations (unpublished information) proved the four ingots to belong to the same assemblage. They are the remains of a set of originally 30 rectangular tin ingots (with trapezoidal cross section) that was found in the 1970s by a fisherman (Adib Shehade) offshore Kfar Samir, Israel ( Table 1 ) [ 30 ]. The ingots were later sold by the fisherman to a tinsmith who used the tin to repair car radiators. From the set, the surviving four ingots were bought from the tinsmith on behalf of the University of Haifa. Further inquiries revealed that the ingots were retrieved some 60 metres north of another underwater site (the Kfar Samir north), which yielded several broken copper (oxhide) and lead ingots [ 25 ]. However, although found relatively close to that site, the rectangular tin ingots may have belonged to a separate shipwreck. The exact context of the tin ingots is still uncertain though because the site was not surveyed with archaeological methods. In the literature, several find locations were specified for these ingots (Haifa, Dor, Atlit), and even though we are aware of the exact location now, we use ‘Haifa’ here so as not to produce further confusion by introducing a new location. Dor [ 31 ] and Atlit [ 32 – 33 ] lie farther south of Haifa and are definitely not the correct locations.

A second shipwreck from around 1200 BCE with a large cargo had been discovered a few years earlier off Cape Gelidonya, Turkey ( Fig 1 ). In addition to raw products, finished objects and a folded tin foil, Bass [ 19 ] documented several kilograms of a whitish material that was considered a corrosion product of tin by Dykstra [ 20 ]. However, Maddin et al. [ 21 ] and Charles [ 22 ] challenged this interpretation because the material contained mainly calcium (71% as CaCO 3 ) and only a small amount of tin (ca. 14% as SnO). Therefore, some scholars hypothesised that the material might be cassiterite ore that was designed to be mixed with metallic copper [ 22 ]. Since then, no other analyses seem to have been carried out, so it is still not clear whether the Gelidonya ship actually carried tin or not. It is also unknown which route the ship took and where the goods came from.

Tin ingots have been recovered more frequently from underwater contexts ( Table 1 ). The best-known examples are the LBA finds from the wreck of the Uluburun ship discovered off the coast of Turkey in 1982 [ 14 – 17 ; 18 ], which sank shortly before 1318 BCE ( Fig 1 ). In addition to 10 tons of copper ingots, the cargo contained glass ingots, faience and resin, objects made of gold, silver, ivory and amber and, strikingly, one ton of tin. Among the finds, there was also a bronze trident representing the closest typological parallel to the trident found at Mochlos [ 14 ]. The unique tin cargo itself comprises ca. 160 ingots of different shapes, including such of oxhide shape, and four finished tin artefacts. The tin ingots was most likely intended to be alloyed with the copper on board, but which port it was destined for and where the tin came from is still an unsolved problem. Pulak [ 18 ] argues for an east-west Mediterranean searoute with the homeport having been situated along the northern Israeli Carmel or southern Lebanon coast.

Map of part of the main settlement of Mochlos with the find location of the tin ingot in storeroom 1.7 (a). Details of the archaeological context inside the storeroom is shown in (b) and a section in north-south direction in (c) (images: modified and reprinted from [ 12 ] under a CC BY license, with permission from the INSTAP Academic Press, original copyright 2007).

In 2004, during an excavation in the Mochlos settlement the tin ingot was unearthed in a storeroom belonging to the western wing of a large ceremonial building [ 7 , 12 – 13 ]. This building–designated B.2 –had many rooms, and next to the storeroom (1.7) with the tin ingot was a large room (1.3), presumably used for a drinking ceremony ( Fig 2A ). On the opposite side, there was another space (1.4) in which six bronze basins were found [ 13 ]. Inside the storeroom 1.7 itself three pithoi were buried in the ground, so that their mouths were just above floor level, a common practice in Minoan houses to store food or beverages. Beneath the largest and innermost pithos, ca. 0.4 metres below ground level, the now completely disintegrated tin ingot was located next to a bronze trident ( Fig 3 ). It had been placed together with the trident before the pithoi were positioned and the earth filled up to the original floor level ( Fig 2B and 2C ). The tin ingot belonged to a precious foundation deposit that was offered to the goddess to whom the building was dedicated and was protected by the trident. As part of a foundation deposit it was laid in place when the building was constructed at the beginning of the Late Minoan IB period, ca. 1530 BCE (terminus ante quem), and lay hidden when the building was destroyed a hundred years later. It is approximately 200 years older than the other ingots discussed in this paper ( Table 1 ).

Tin ingots, the subject of this paper, are a special group of artefacts. They represent a specific type of trade goods, and a small number of them, dating from the Late Bronze Age (LBA), were discovered in the eastern Mediterranean area ( Table 1 and Fig 1 ). One rare example, and to date the only one from a terrestrial context in the whole Mediterranean region, is the tin ingot from Mochlos ( Fig 1 ). The Minoan settlement is located on a small island very close to the north-eastern coast of Crete. The island was connected to the Cretan mainland through a land bridge that was exposed until Hellenistic times. The site was an important commercial centre throughout the Bronze Age (BA), but in particular during the Neopalatial period (1700–1425 BCE). It had rich metal and pottery traditions, was an important trading port along the routes to and from Cyprus and the Levant, and was also a religious centre [ 7 ; 9 ]. It was destroyed by earthquakes in the Neopalatial period, especially at the time of the Santorini eruption (around 1530 BCE) when a large number of buildings had to be rebuilt and the metal and pottery workshops were moved to the coast of the Cretan mainland [ 10 – 11 ].

1: Mochlos (Crete), Greece, 2: Uluburun, Turkey, 3: Gelidonya, Turkey, 4: Hishuley Carmel, Israel, 5: Kfar Samir south, Israel, 6: Haifa, Israel, 7: Thermi (Lesbos), Greece, 8: Athens, Greece, 9: Phylakopi (Milos), Greece, 10: Rethymno (Crete), Greece, 11: Knossos (Crete), Greece, 12: Kalydon (Crete), Greece, 13: Ialysos (Rhodos), Greece, 14: Salamis (Cyprus), Turkey, 15: Alaca Höyük, Turkey, 16: Tülintepe, Turkey, 17: Mycenae, Greece, 18: Dendra, Greece, 19: Abydos, Egypt, 20: Gurob, Egypt, 21: Tell Abraq, United Arab Emirates, 22: Tepe Yahya, Iran, 23: Salcombe, United Kingdom, 24: Erme Estuary, United Kingdom, 25: S’Arcu e is Forros, Sardinia, Italy, 26: Cornwall/Devon, United Kingdom, 27: Mourne Mountains, Down County, North Ireland (United Kingdom), 28: Brittany, France, 29: Massif Central, France, 30: North Portugal/Spain, 31: Erzgebirge province with the Bohemian-Saxon Erzgebirge, Vogtland, Fichtelgebirge, Kaiserwald (Slavkovský les), 32: Slovak Ore Mountains, Slovak Republic, 33: Mt. Cer, Serbia, 34: Mt. Bukulja, Serbia, 35: Monte Valerio, Italy, 36: Sardinia, Italy, 37: Kestel, Turkey, 38: Hisarcık, Turkey, 39: Eastern Desert, Egypt, 40: Deh Hosein, Iran, 41: Western Afghanistan (Herat and Farah provinces), 42: Central/north-eastern Afghanistan (Hindu Kush), 43: Karnab/Lapas/Čangali (Zeravšan valley), Uzbekistan, 44: Mušiston/Takfon (Hissar Mountains), Tadzhikistan, 45: Pamir, Tadzhikistan, 46: Kyrgyzstan, 47: Tosham, Bhiwani district, India, 48: Bastar district/Koraput district, India, 49 (not on the map): Kazakhstan. Size of green and yellow symbols on the inset map do not correlate with number of objects as on the main map (map: D. Berger, C. Frank using Natural Earth geo data and QGIS Geographic Information System. QGIS Development Team, 2019. Open Source Geospatial Foundation. http://qgis.org ).

Tin objects are extremely rare in the archaeological record, and only very few are known from prehistoric contexts (for artefacts in the eastern Mediterranean and the Near East dating from before 1000 BCE see Fig 1 ; summary of Eurasian finds in [ 1 ]). This is probably due to a number of reasons. Unalloyed tin corrodes easily in a damp environment in which corrosion stimulators such as chlorides or sulphates are present (for example at the seaside) [ 2 – 4 ]. Deterioration may be enhanced at low temperatures, less than 13°C, when the crystal structure of tin changes, turning the white metal to a grey powder. This so-called tin pest is often stated in archaeological literature [ 5 – 8 ], but since its occurrence has not yet been confirmed on prehistoric artefacts its contribution to the problem is certainly small. Because of this and because corrosion does not make objects simply disappear, socio-economic factors and the predominant usage of tin for the production of bronze are the more likely explanations for the general rarity of ancient tin objects.

In this paper we intend to follow up the approach of the early studies by presenting new tin and lead isotope data of tin ingots and by comparing them with an enlarged data base of tin ores. Almost all ingots from the eastern Mediterranean that have been previously studied are reconsidered here ( Table 2 ), and the older data is critically reviewed. At the same time, we investigate the Mochlos tin ingot in more detail since this has not been done before. This involves metallographic examination and analyses with scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX) as well as X-ray diffractometry (XRD). The study is completed by the determination of the chemical composition of many tin ingots. The ultimate goal of this combined approach is once again to unravel the history and provenance of the tin in the ingots.

It is therefore more advantageous to use the isotope composition of the main constituent of the ingots, i.e. the tin itself. Recent studies have confirmed that the tin isotope composition of ores and metals is of great value for the sourcing of tin and the establishment of relationships between artefacts [ 1 ; 66 – 71 ]. The pioneering studies on tin isotopes carried out on some tin ingots from Hishuley Carmel, Kfar Samir south, Haifa and Uluburun have already revealed similarities and differences in the isotope composition [ 31 – 33 ; 72 – 73 ], but no conclusions could be drawn on the origin of the tin in those studies because of the lack of ore data. Only a dozen ores from very different locations were characterised in those days.

So far, chemical analyses of the ingots from Uluburun, Hishuley Carmel, Kfar Samir south and Haifa have not provided suitable fingerprints unveiling the provenance of the tin (for references cf. Table 2 ). This is mainly because unalloyed tin is commonly quite pure with only a few trace elements partitioning to the metal phase during the smelting of tin ores [ 62 – 64 ]. Several studies determined lead isotope ratios of the tin ingots from the Mediterranean area (for references cf. Table 2 ), but since the tin ore–and also the tin–usually contains very low lead concentrations of less than ca. 100 μg g -1 contaminations with lead from the smelting structures, fuel or aggregates could easily modify the isotope signature [ 65 ]. Accordingly, conclusions about the provenance which are based only on the lead isotope ratios are ambiguous if lead contamination cannot be excluded.

Geographically not too distant tin deposits of significant scale are located in the eastern Desert of Egypt ( Fig 1 ), but they do not seem to have been exploited in prehistoric times [ 48 , 51 – 52 ]. Large mineralisations in western and central Europe, such as those in Cornwall/Devon, United Kingdom, in Brittany and the Massif Central, France, the Iberian peninsula and the Saxon-Bohemian tin province with the Erzgebirge (Krušné hory), the Fichtelgebirge, the Vogtland and the Kaiserwald (Slavkovský les) have been suggested as possible sources for cassiterite used for Mediterranean and Near Eastern tin-bearing objects. However, the large deposits in central Asia, especially in Afghanistan, are currently considered the most likely sources of tin. This view is mainly based on text documents, rare trade goods such as lapis lazuli and lead isotope data of bronzes [ 47 – 48 ; 53 – 55 ]. Apart from some weak indications [ 56 ], compelling archaeological evidence for the exploitation of tin ores in Afghanistan, however, is still lacking [ 57 ]. On the other hand, 14 C dates from prehistoric workings indicate active tin mining in Uzbekistan, Tadzhikistan or Kazakhstan during the late 3 rd and the 2 nd millennia BCE [ 58 – 61 ]. However, direct relationships of tin and bronze artefacts from the Eastern Mediterranean region and the Near East could not yet be established with these tin ores.

Because of their rarity, it is hardly surprising that many of the ingots listed above have been analysed in the past, some even a couple of times, by various research groups ( Table 2 ). The primary aim was always to unveil the origin of the tin, but questions regarding trade routes also arose since tin had to be transported and traded over long distances because of insignificant cassiterite resources in the Mediterranean World. Despite a number of tin-containing minerals (such as stannite, mushistonite and kësterite), cassiterite was the only economically usable tin ore mineral in prehistoric times. With the exception of the disputed tin occurrences at Kestel and Hisarcık, Turkey [ 36 – 41 ] and small mineralisations on Sardinia and at Monte Valerio, Italy [ 42 – 46 ], there are no large-scale exploitable tin deposits in the vicinity of the places where the tin ingots were found ( Fig 1 ). The problem of the cassiterite sources also applies to the great many BA bronzes from the eastern Mediterranean region and the Near East [ 47 – 51 ].

In addition to the chemical and isotopic investigations, X-ray diffraction analysis served for the determination of the mineralogical composition of the corroded ingot samples. Powder samples of the Mochlos and Uluburun ingots, which were prepared for TIA, were analysed in the Institute for Geosciences, Heidelberg University (H.-P. Meyer), Germany, with a D8 ADVANCE eco powder diffractometer (Bruker AXS GmbH, Karlsruhe, Germany). Analytical parameters are documented in S1 Table along with the other analytical instruments used in this study.

The lead isotope ratios of most of the tin ingots were also determined using solution aliquots and an established and improved analytical protocol [ 86 ] with substantially improved precision of better than 0.003% in all ratios. The measurements were also performed in the Mannheim laboratory with the Neptune Plus mass spectrometer.

In contrast to the metallic samples, the corroded specimens of the Mochlos and Uluburun ingots had to be converted to tin metal prior to TIA because common corrosion products of tin, such as stannic oxide (SnO 2 ) and hydrated stannic oxide (SnO 2 ·nH 2 O) [ 82 – 83 ], are almost insoluble in acids (although stannic oxide is identical with cassiterite we use the term for the corrosion product in order to distinguish it from the natural ore mineral). Conversion to tin metal was achieved by reduction of a small amount of pulverised material (~10 mg) in a muffle furnace at 950°C, according to the protocol established by Berger et al. [ 70 ]. In order to prevent tin loss during heating due to the formation of volatile SnO [ 84 ], reduction was performed in presence of potassium cyanide (KCN) using graphite crucibles ( Fig 5 ). This is the most reliable procedure for cassiterite/stannic oxide reduction, as no tin loss and isotopic fractionation due to evaporation has been observed so far [ 64 ; 70 ; 85 ]. After reduction, the tin metal was processed for TIA like the Israeli specimens. The approach was the same for the preparation and characterisation of Eurasian cassiterite ores that are employed for comparison in this study. Ore samples are summarised in S3 Table , but without specification of numerical values of their tin isotope composition. Values and geological interpretation will be supplied in a forthcoming PhD thesis (J. Marahrens). The combined analytical uncertainty (2SD) for multiple measurements of certified bronze reference materials (BAM 211, IARM-91D) arising from the sample processing and the measurements was ± 0.02 ‰ for δ 124 Sn [ 74 ]. All analytical errors specified for the tin isotope ratios of the individual tin samples are given as 2SD.

A Neptune Plus (Thermo Scientific, Bremen, Germany) multi-collector mass spectrometer with inductively-coupled plasma ionisation (MC-ICP-MS) was employed for the isotopic analyses. It was equipped with nine Faraday cups measuring simultaneously seven stable tin isotopes ( 116 Sn, 117 Sn, 118 Sn, 119 Sn, 120 Sn, 122 Sn, 124 Sn) and two antimony isotopes ( 121 Sb, 123 Sb) for mass bias correction. Since there is still no internationally certified tin reference material, an in-house standard was prepared from ultraclean tin metal (Puratronic, Batch W14222, Johnson Matthey, Royston, GB) by dissolving it in HCl. This metal had already been used in previous studies [ 31 – 33 ; 64 ; 70 ; 72 ; 75 – 81 ]. The isotopic ratios reported here are related to the in-house standard and are given in the delta notation in units of permil (‰) with 120 Sn as the common denominator. δ 124 Sn, which is used for discussion hereafter, would thus represent δ 124 Sn/ 120 Sn [ 74 ]. For better comparisons with other studies the isotope compositions are also given as δSn in in ‰ per atomic mass unit (‰ u -1 ) in the supplementary material ( S2 Table ).

Aliquots of the sample solutions were used for tin isotope analysis (TIA) after dilution with deionised water and 0.4 N HNO 3 + concentrated HF and processed further as described in detail by Brügmann et al. [ 74 ]. No chemical separation was necessary before the isotopic measurements because the metal consisted of almost pure tin, and potential isobaric interferences of cadmium, antimony, arsenic or tellurium were not observed. An antimony solution with known isotope composition (Specpure ICP–AES, Lot#. PSBH24/13, supplied by Fisher Chemicals) was added to the sample solutions as an internal standard in order to correct the mass discrimination occurring during the measurements in the mass spectrometer.

The chemical composition of the Israeli ingots was determined with the same quadrupole device, but using sample solutions. For this purpose, metal drillings were mechanically cleaned to remove surface contaminations. All samples (2–10 mg) were dissolved in a mixture of 6N HCl with small amounts of H 2 O 2 in Teflon beakers on a hotplate (80°C). Thereafter, aliquots of the samples were diluted to 0.5N HCl and scandium, tamarium and rhenium (all Merck KGaA, Darmstadt, Germany) were added as internal standards. In case of solution measurements, tin concentrations are based upon 100% normalisation. A tin-lead metal standard (NF-2, Alpha Analytical Laboratories, Jersey City, USA) used for quality control mostly obtained results in good agreement with the reported values (Au, Bi, Sn calc <5%; As, Cu, Sb, In within 5–10%; Cd, Ag 10–20%). Iron (20%), zinc (400%) and nickel (90%) values are reported as strongly influenced by segregation effects and were therefore not reliable for quality control.

The Mochlos sample was embedded in epoxy resin for metallographic examination on polished section. It was ground with SiC papers up to 1200 grit and polished with diamond and alumina suspensions down to 0.25 μm. The microstructure was studied using optical (OM; Axioskop 40, Zeiss) and scanning electron microscopy (SEM; Evo MA 25, Zeiss). Analyses with an energy dispersive X-ray micro-analyser (EDX; Quantax 400, Bruker AXS) integrated in the SEM were carried out standardless to identify metallic and non-metallic phases and to estimate the bulk chemical composition of the ingot. In addition, the bulk composition ( 55 Mn, 57 Fe, 59 Co, 60 Ni, 63 Cu, 66 Zn, 75 As, 93 Nb, 107 Ag, 111 Cd, 113 In, 121 Sb, 126 Te, 181 Ta, 182 W, 197 Au, 206 Pb, 209 Bi) was determined directly on the polished cross-section using a laser ablation quadrupole inductively coupled plasma mass spectrometry approach (LA-Q-ICP-MS; ATL ArF 193nm, Resonetics and XSeries II Thermo Scientific). The badly corroded Uluburun objects were treated the same way, but only one of them was prepared metallographically (FG-883208). The other strongly corroded powder samples from the Uluburun tin ingots were analysed using pressed binderless pellets. Transient signals were recorded using Thermo PlasmaLab software. Signals were gas-blank-subtracted and spikes were excluded. The NIST 610 glass was used as external standard for quantification with 122 Sn from the above-mentioned approach (EDX) as internal standard. An in-house excel-spread sheet was used for data-processing.

Tin ingots from the above-mentioned sites, with the exception of the Gelidonya shipwreck, were chosen for the present study and analysed in the laboratory of the Curt-Engelhorn-Zentrum Archäometrie Mannheim, Germany (CEZA). This includes 14 out of 15 ingots of the Hishuley Carmel wreck, seven of a total of ten of the Kfar Samir south wreck and two of the supposed shipwreck off the coast of Haifa, all of which consisted of well-preserved tin metal. Three ingots of the Uluburun wreck (with two samples from the same ingot KW 203) were also examined, but they were entirely corroded. As compiled in Table 3 , almost all samples were analysed previously regarding their chemical and lead and tin isotope compositions (cf. acknowledgements). The Mochlos ingot is the only object from which a new sample was taken.

4. Results and discussion