Cite this as: Wood, J.R., Ponting, M. and Butcher, K. 2023 Mints not Mines: a macroscale investigation of Roman silver coinage, Internet Archaeology 61. https://doi.org/10.11141/ia.61.10
Although silver coins have been investigated through the lens of geological provenance to locate argentiferous ore deposits exploited in their production, we consider that this avenue of research may be a cul-de-sac, especially for studies that rely heavily on deciphering lead and silver isotope signatures that may have been altered by the addition of lead and copper (and their associated impurities) during silver refining and debasement, and by ancient recycling of coinage. Instead, we focus our attention on mints, by analysing the compositions of over 1000 silver coins from the early 1st century BC to AD 100. We propose that lead from the west Mediterranean was used exclusively to refine silver at mints in the West, and that an unknown lead supply (possibly from Macedonia), used in the East by the Late Seleucid ruler Philip I Philadelphus and later Mark Antony, was mixed with western lead. Extensive mixing of lead and/or silver coins is particularly evident under Nero and Vespasian, aligning with historically attested periods of recycling following currency reform. We further propose that coins minted in the kingdom of Mauretania used different lead and silver sources from the majority of coins minted in the western Mediterranean, and that silver coins minted at Tyre are derived from silver refined in the west Mediterranean. Coinage minted at Alexandria is consistent with debasement of recycled Roman denarii, thereby suggesting that denarii were deliberately removed from circulation to mint tetradrachms during the early Imperial Roman period.
Corresponding author: Jonathan R. Wood
University of Liverpool
University of Warwick
Figure 1: Distributions of a continuous trait: a) the variance within groups is greater than the variance between groups; b) the variance between groups is greater than the variance within groups. Mixing batches (e.g. silver coins): c) a stable mean, and fluctuating variance (i.e. the mean of the mixture is the same as those of the individual batches); d) a fluctuating mean, and stable variance (i.e. the means of the individual batches converge in the mixture). Adapted from Perreault 2019, fig. 3.12.
Figure 2: Lead isotope plot for 208Pb/204Pb vs. 206Pb/204Pb for the coins from the Denarii and Provincial datasets, delineated by the geographical regions of the mints: East, Rome and West.
Figure 3: Histograms of the ages of the lead in millions of year (Ma) associated with the coins, calculated from the LIA values for the coins from the Denarii and Provincial datasets using the model and parameters of Albarède and colleagues. The data have been delineated by the geographical regions of the mints: Rome (upper left), East (upper right), West (lower left) and East and West combined (lower right).
Figure 4: Histograms of the silver concentrations (%) in the coins from the Denarii and Provincial datasets for emperors (i.e. leaders) delineated by the geographical regions of the mints: East (purple); Rome (brown) and West (green). Emperors with few coins associated with their names were not plotted as there were insufficient coins to build a histogram. Coins from the Civil War (AD 69) are anonymous. The coins from Antony include 11 legionary denarii and one cistophorus. All the Hellenistic coins were minted at Tyre. Note the different scales on the y-axis, reflecting the number of coins available for testing.
Figure 5: Boxplots of log (Au/Ag) for the coins from the Denarii and Provincial datasets, delineated by the geographical regions of the mints. The boxes indicate the medians and interquartile ranges (IQR). The whiskers indicate points that fall within 1.5 × IQR. Jitter has been applied to the points to prevent obscuring values due to overlaps.
Figure 6: Boxplots of log (Bi/Pb) for the coins from the Denarii and Provincial datasets, delineated by the geographical regions of the mints. The boxes indicate the medians and interquartile ranges (IQR). The whiskers indicate points that fall within 1.5 × IQR. Jitter has been applied to the points to prevent obscuring values due to overlaps.
Figure 7: Histograms of the ages of the lead in millions of year (Ma) associated with Roman lead ingots from Cartagena in south-east Iberia (Trincherini et al. 2009) and the ages of galena in metalliferous regions in Iberia (Milot et al. 2021). Ages calculated from the LIA values using the model and parameters of Albarède and colleagues
Figure 8: Lead isotope plot for (a) 208Pb/204Pb vs. 206Pb/204Pb and (b) 208Pb/206Pb vs. 207Pb/206Pb for the coins from the Denarii and Provincial datasets from the East geographical region. The coins plotted are those with low crustal ages (<200Ma) (see Figure 3 - upper right). The grey triangles denote the LIA values of lead ingots from Cartagena in south-east Iberia (Trincherini et al. 2009).
Figure 9: Logratio analysis (LRA) of the compositional data for the coins from the Denarii and Provincial datasets with 95% confidence ellipses around the group means of the twelve groups (large symbols: Alexandria (Al: 103), Antioch (An: 144), Antony (Ao: 11), Caesarea (Ca: 38), Cyprus (Cy:10), Ephesus (E: 20), Gaul (G: 19), Lyon (L: 60), Spanish (S: 20), Tyre (T: 9), Mauretania (M: 12), Rome (R: 577)). 61.6% of the variance is explained by the two principal dimensions.
Figure 10: a) PCA of the six logratios selected, which account for 94.1% of the total logratio variance. Since 26.0 + 51.3 = 77.3% of the variance is explained by these two dimensions, this means that 0.773 x 94.1 = 72.7% of the total logratio variance is explained by this two-dimensional solution. The main separation of groups is along dimension 1. However, the overlapping logratios of Sb/Zn, Au/Sn and Sb/Sn suggest that groups can be differentiated along dimension 2 (e.g. Lyon, Spanish and Gaul). b) Boxplots of log(Sb/Zn) for silver coins from Gaul, Lyon and Spanish mints. The boxes indicate the medians and interquartile ranges (IQR). The whiskers indicate points that fall within 1.5 × IQR. Jitter has been applied to the points to prevent obscuring values due to overlaps.
Figure 11: Scatterplot of the two logratios, log(Cu/Bi) and log(Au/Cu), for the coins from the Denarii and Provincial datasets delineated by the mints.
Figure 12: Density plots showing regions of varying densities of coins on the bivariate plot of the logratios of (Cu/Bi) and (Au/Cu) delineated by geographical region (a). There appear to be three groups (b) of high density for the East (East Groups 1, 2 and 3) and (c) Rome (Rome Groups 1, 2 and 3) and (d) one for the West (West Group 1) (although a second appears to be emerging). Coins were extracted from inside contours that enclosed a region of high density (lowest density = 0.7; highest density = 0.1): East (0.5), Rome (0.25) and West (0.25).
Figure 13: (a) Plots of Au/Ag × 100, (b) Plots of log(Bi/Pb) and (c) Plots of the Pb crustal age (Ma) for the clusters identified from the LRA and PCA delineated by regions: East, Rome and West. Note that there appears to be a bimodal signature for log(Bi/Pb) in the East and Rome data and that an approximate value of log(Bi/Pb) ≈ -5 is used to delineate the two peaks; that is low-bismuth lead <-5, and high-bismuth lead >-5. This empirical limit is applied to investigate silver coinage in Figures 14, 15 and 16.
Figure 14: Histograms of log(Bi/Pb) for the coins from the West mints for the rulers under whom the coins in the dataset were minted. Civil War coins are anonymous. The red dashed line is an empirically determined limit between lead with high and low levels of bismuth determined from Figure 13.
Figure 15: Histograms of log(Bi/Pb) for the coins from the East mints for the emperors/rulers under whom the coins in the dataset were minted. Emperors/Rulers with few coins under their name have not been plotted, unless specifically referred to in the text. Hellenistic coins are all attributed to the mint at Tyre. The coins of Philip (Philip I Philadelphus, of the Seleucid kingdom) are those minted in his lifetime (c. 94-83 BC). Posthumous Philip are coins struck with his likeness in the late Republican period. Coins of Antony are denarii from the Denarii dataset, apart from the single cistophorus (log(Bi/Pb) ≈ -3) which is from the Provincial dataset. The red dashed line is an empirically determined limit between lead with high and low levels of bismuth determined from Figure 13.
Figure 16: Histograms of log(Bi/Pb) for the coins from the Rome mint for the Emperors under whom the coins in the dataset were minted. The red dashed line is an empirically determined limit between lead with high and low levels of bismuth determined from Figure 13.
Figure 17: Lead isotope plots for (a) 208Pb/204Pb vs 206Pb/204Pb and (b) 207Pb/204Pb vs 206Pb/204Pb for the coins from the Denarii and Provincial datasets, delineated by the geographical regions of the mints: East, Rome and West. The black squares denote the LIA values of lead ingots recovered in Germania (Bode 2008; Bode et al. 2009). The red diamonds are from the LIA analyses conducted on lead pipes at Pompeii (Boni et al. 2000).
Figure 18: Lead isotope plot for (a) 208Pb/204Pb vs 206Pb/204Pb and (b) 207Pb/204Pb vs 206Pb/204Pb for the coins from the Denarii and Provincial datasets with values of log(Bi/Pb) <-5, delineated by the geographical regions of the mints: East and Rome. The black squares denote the LIA values of lead ingots recovered in Germania (Bode 2008; Bode et al. 2009). The red diamonds are from the LIA analyses conducted on lead pipes at Pompeii (Boni et al. 2000). The LIA values for British lead and silver is from Ponting (2018). The grey inverted triangles are from the Augustan shipwreck of Comacchio (Ferrara, Italy), provenanced by Bode et al. (2021) to Macedonia. The coins of Philip (minted at Antioch) and Antony highlight that coins minted in the East during the late Republican period appear to separate from those minted in the Imperial period.
Table 1: Groups of coins identified from the density plots in Figure 12. The number of coins and the mints and emperors/rulers associated with the coins in each group are presented.
Table 2: Mean, standard deviation and median of the compositions of the coins in each group identified from the density plot in Figure 12. The log(Au/Ag) and log(Bi/Pb) ratios and the Pb crustal age values determined form the LIA are also presented. n denotes the number of coins in each group. NLIA denotes the number of coins in each group with LIA measurements.
Table 3: Comparison of the compositional data of overlapping clusters (see Tables 1 and 2 for details).
Table 4: Comparison of the compositional data of East Group 1 and Rome Group 1 (see Tables 1 and 2 for details) with the calculated dilution of Rome Group 1 in a 1:3 silver to copper debasement ratio.
Table 5: Elemental and lead isotope data for seven denarii that lie below the main LIA data in Figure 2. Elemental values are in parts per million (ppm), apart from silver and copper which are in wt%.
Aitchison, J. 1986 The Statistical Analysis of Compositional Data, London: Chapman and Hall.
Aitchison, J. 2005 'A concise guide to compositional data analysis. 2nd Compositional Data Analysis Workshop - CoDaWork'05', Girona: Universitat de Girona. http://www.leg.ufpr.br/lib/exe/fetch.php/pessoais:abtmartins:a_concise_guide_to_compositional_data_analysis.pdf. [Last accessed: 10 January 2023].
Aitchison, J. and Greenacre, M. 2002 'Biplots for compositional data', Journal of the Royal Statistical Society, Series C (Applied Statistics) 51, 375-92. https://doi.org/10.1111/1467-9876.00275
Albarède, F., Desaulty, A.-M. and Blichert-Toft, J. 2012 'A geological perspective on the use of Pb isotopes in archaeometry', Archaeometry 54, 853-67. https://doi.org/10.1111/j.1475-4754.2011.00653.x
Albarède, F., Blichert-Toft, J., Rivoal, M. and Telouk, P. 2016 'A glimpse into the Roman finances of the Second Punic War through silver isotopes', Geochemical Perspective Letters 2, 127-37. https://doi.org/10.7185/geochemlet.1613
Albarède, F., Blichert-Toft, J., de Callataÿ, F., Davis, G., Debernardi, P., Gentelli, L., Gitler, H., Kemmers, F., Klein, S., Malod-Dognin, C., Milot, J., Telouk, P., Vaxevanopoulos, M. and Westner, K. 2021 'From commodity to money: the rise of silver coinage around the Ancient Mediterranean (sixth-first centuries BCE)', Archaeometry 63, 142-55. https://doi.org/10.1111/arcm.12615
Anguilano, L. 2012 Roman lead and silver smelting at Rio Tinto: the case study of Corta Lago, Unpublished PhD thesis, University College London.
Anguilano, L., Rehren, T., Muller, W. and Rothenberg, B. 2009 'Roman jarosite exploitation at Rio Tinto (Spain)' in A. Giumlia-Mair and A. Hauptmann (eds) Archaeometry in Europe II 2007, Milano: Associazione Italiana di Metallurgia. 21-29.
Arribas, A., Mathur, R., Megaw, P. and Arribas, I. 2020 'The isotopic composition of silver in ore minerals', Geochemistry, Geophysics, Geosystems 21, e2020GC009097. https://doi.org/10.1029/2020GC009097
Baxter, M.J. 1989 'Multivariate analysis of data on glass compositions: a methodological note', Archaeometry 31, 45-53. https://doi.org/10.1111/j.1475-4754.1989.tb01055.x
Birch, T., Westner, K.J., Kemmers, F., Klein, S., Höfer, H.E. and Seitz, H.-M. 2020 'Retracing Magna Graecia's silver: coupling lead isotopes with a multi-standard trace element procedure', Archaeometry 62, 81-108. https://doi.org/10.1111/arcm.12499
Bode, M. 2008 Archäometallurgische Untersuchungen zur Blei-/Silbergewinnung im Germanien der frühen Römischen Kaiserzeit, Unpublished PhD thesis, Westfälischen Wilhelms-Universität Münster.
Bode, M., Hauptmann, A. and Mezger, K. 2009 'Tracing Roman lead sources using lead isotope analyses in conjunction with archaeological and epigraphic evidence - a case study from Augustan/Tiberian Germania', Archaeological and Anthropological Sciences 1, 177. https://doi.org/10.1007/s12520-009-0017-0
Bode, M., Hanel, N. and Rothenhöfer, P. 2021 'Roman lead ingots from Macedonia - the Augustan shipwreck of Comacchio (prov. Ferrara, Italy) and the reinterpretation of its lead ingots' provenance deduced from lead isotope analysis', Archaeological and Anthropological Sciences 13, 163. https://doi.org/10.1007/s12520-021-01430-0
Boni, M., Maio, G.D., Frei, R. and Villa, I.M. 2000 'Lead isotopic evidence for a mixed provenance for Roman water pipes from Pompeii', Archaeometry 42, 201-8. https://doi.org/10.1111/j.1475-4754.2000.tb00876.x
Butcher, K. and Ponting, M. 2015 The Metallurgy of Roman Silver Coinage: From the reform of Nero to the reform of Trajan, Cambridge University Press. https://doi.org/10.1017/CBO9781139225274
Buxeda i Garrigos, J. 1999 'Alteration and contamination of archaeological ceramics: the perturbation problem', Journal of Archaeological Science 26, 295-313. https://doi.org/10.1006/jasc.1998.0390
Buxeda i Garrigos, J. 2008 'Revisiting the compositional data: some fundamental questions and new prospects in archaeometry and archaeology', Proceedings of CODAWORK 8, 27-30.
Cartwright, M. 2018 'Roman Coinage', World History Encyclopedia. https://www.worldhistory.org/Roman_Coinage/ [Last accessed: 10 January 2023].
Challis, C.E. 1978 The Tudor Coinage, Manchester: Manchester University Press.
Chayes, F. 1949 'On correlation in petrography', The Journal of Geology 57, 239-54. https://doi.org/10.1086/625606
Craddock, P.T., Freestone, I.C. and Hunt Ortiz, M. 1987 'Recovery of silver from speiss at Rio Tinto (SW Spain)', IAMS Newsletter. https://www.ucl.ac.uk/archaeo-metallurgical-studies/sites/archaeo-metallurgical-studies/files/iams_10-11_1987_craddock_freestone_ortiz.pdf. [Last accessed: 10 January 2023].
Crawford, M. 1974 Roman Republican Coinage, 2 vols, Cambridge: Cambridge University Press.
Crawford, M. 1987 'Sicily' in A. Burnett and M. Crawford (eds) The Coinage of the Roman World in the Late Republic, British Archaeological Reports International Series 326, Oxford: BAR Publishing. 43-51.
Desaulty, A.-M. and Albarède, F. 2013 'Copper, lead, and silver isotopes solve a major economic conundrum of Tudor and early Stuart Europe', Geology 41, 135-38. https://doi.org/10.1130/G33555.1
Desaulty, A.-M., Telouk, P., Albalat, E. and Albarède, F. 2011 'Isotopic Ag-Cu-Pb record of silver circulation through 16th-18th century Spain', PNAS 108, 9002-9007. https://doi.org/10.1073/pnas.1018210108
Domergue, C. 1983 'La mine antique d'Aljustrel (Portugal) et les tables de bronze de Vipasca', Conimbriga 22, 5-193. https://doi.org/10.14195/1647-8657_22_1
Domergue, C. 1990 'Les mines de la péninsule ibérique dans l'antiquité romaine', Collection de l'École française de Rome 127. https://www.persee.fr/doc/efr_0000-0000_1990_ths_127_1
Domergue, C., Quarati, P., Nesta, A. and Trincherini, P.R. 2012 'Retour sur les lingots de plomb de Comacchio (Ferrara, Italie) en passant par l'archeometrie et l'epigraphie' in A. Orejas and Ch. Rico (eds) Mineria y metalurgia antiguas. Visiones y revisiones. Homenaje a Claude Domergue, Collection de la Casa de Velazquez 128, Madrid: Casa de Velazquez. 81-103. https://doi.org/10.4000/books.cvz.17389
Elliot, C.P. 2020 'The role of money in the economies of Ancient Greece and Rome' in S. Battilossi, Y. Cassis and K. Yago (eds) Handbook of the History of Money and Currency, Singapore: Springer. 67-86. https://doi.org/10.1007/978-981-13-0596-2_46
Eshel T., Tirosh O., Yahalom-Mack N., Gilboa A. and Erel Y. 2022 'Silver Isotopes in silver suggest Phoenician innovation in metal production', Applied Sciences 12(2), 741. https://doi.org/10.3390/app12020741
Frei, R. 1992 Isotope (Pb, Rb-Sr, S, O, C, U-Pb) geochemical investigations on Tertiary intrusives and related mineralizations in the Serbomacedonian Pb-Zn, Sb+Cu-Mo metallogenetic province in Northern Greece, Unpublished PhD thesis, Swiss Federal Institute of Technology (ETH) Zürich, Switzerland.
Gale, N.H., Gentner, W. and Wagner, G.A. 1980 'Mineralogical and geographical silver sources of archaic Greek coinage' in D.M. Metcalf and W.A. Oddy (eds) Metallurgy in Numismatics I, London: The Royal Numismatic Society.
Gale, N.H., Stos-Gale, Z.A. and Davis, J.L. 1984 ' The provenance of lead used at Ayria Irini, Keos', Hesperia 53, 389-406. https://doi.org/10.2307/148020
Greenacre, M. 2016 'Data reporting and visualization in ecology', Polar Biology 39, 2189-2205. https://doi. org/ 10. 1007/ s00300- 016- 2047-2
Greenacre, M. 2018 Compositional Data Analysis in Practice, Boca Raton: Chapman and Hall/CRC Press. https://doi.org/10.1201/9780429455537
Greenacre, M. 2019 'Variable selection in compositional data analysis using pairwise logratios', Mathematical Geosciences 51, 649-682. https://doi.org/10.1007/s11004-018-9754-x
Greenacre, M. 2021 'Compositional data analysis', Annual Review of Statistics and its Application 8, 271-299. https://doi.org/10.1146/annurev-statistics-042720-124436
Hirt, A.M. 2010 Imperial Mines and Quarries in the Roman World: Organizational Aspects 27BC-AD235, Oxford: Oxford Classical Monographs. https://doi.org/10.1093/acprof:oso/9780199572878.001.0001
Hirt, A. 2020 'Gold and silver mining in the Roman Empire' in K. Butcher (ed) Debasement. Manipulation of Coin Standards in Pre-Modern Monetary Systems, Oxford: Oxbow Books. 111-24. https://doi.org/10.2307/j.ctv138wssp.13
Hunt Ortiz, M.A. 2003 Prehistoric Mining and Metallurgy in south west Iberian Peninsula, British Archaeological Reports International Series 1188, Oxford: BAR Publishing. https://doi.org/10.30861/9781841715544
Jessop-Price, M. 1980 'The uses of metal analysis in the study of archaic Greek coinage: some comments' in D.M. Metcalf and W.A. Oddy (eds) Metallurgy in Numismatics I, London: The Royal Numismatic Society.
Johnson, C. (ed) 1956 The De Moneta of Nicholas Oresme and English Mint Documents, Alabama: Ludwig von Mises Institute.
Jones, J.R.M. 2015 'The location of the Trajanic Mint at Rome', The Numismatic Chronicle (1966-) 175, 137-45. http://www.jstor.org/stable/43859785
Krzywinski, M. and Altman, N. 2013 'Error bars', Nature Methods 10, 921-22. https://doi.org/10.1038/nmeth.2659
L'Heritier, M., Baron, S., Cassayre, L. and Tereygeol, F. 2015 'Bismuth behaviour during ancient processes of silver-lead production', Journal of Archaeological Science 57, 56-68. https://doi.org/10.1016/j.jas.2015.02.002
Mathur, R., Arribas, A., Megaw, P., Wilson, M., Stroup, S., Meyer-Arrivillaga, D. and Arribas, I. 2018 'Fractionation of silver isotopes in native silver explained by redox reactions', Geochimica et Cosmochima Acta 224, 313-26. https://doi.org/10.1016/j.gca.2018.01.011
Meadows, A. 2020 Between Greece and Rome: coinage in the Imperium of Mark Antony, Memoranda Numismatica Atheniensia 4, Athens: Benaki Museum & KIKPE. https://kikpe.gr/memoranda-numismatica-atheniensia-4/
Merkel, J.F. 2007 'Imperial Roman production of lead and silver in the northern part of upper Moesia (Mt Kosmaj area)', Journal of the Serbian Archaeological Society 23, 39-78.
Meyers, P. 2003 'Production, distribution, and control of silver: information provided by elemental composition of ancient silver objects' in L. van Zelst (ed) Patterns and Process: A Festschrift in Honor of Dr Edward V. Sayre, Washington, DC: Smithsonian Center for Materials Research and Education. 271-88
Milot, J., Malod-Dognin, C., Blichert-Toft, J., Telouk, P. and Albarède, F. 2021 'Sampling and combined Pb and Ag isotopic analysis of ancient silver coins and ores', Chemical Geology 564, 120028. https://doi.org/10.1016/j.chemgeo.2020.120028.
Milot, J., Blichert-Toft, J., Ayarzagüena Sanz, M., Malod-Dognin, C., Telouk, P. and Albarède, F. 2022 'Silver isotope and volatile trace element systematics in galena samples from the Iberian Peninsula and the quest for silver sources of Roman coinage', Geology 50, 422-26. https://doi.org/10.1130/G49690.1
Mladenovic, D. 2009 Roman Moesia Superior: the creation of a new provincial entity and processes of multicultural adjustment, Unpublished DPhil thesis, University of Oxford.
Montero-Ruiz, I., Gener, M., Hunt, M., Renzi, M. and Rovira, S. 2008 'Caracterización analítica de la producción metalúrgica protohistórica de plata en Cataluña', Revista d'arqueologia de Ponent 18, 292-316. https://raco.cat/index.php/RAP/article/view/251824.
Murillo-Barroso, M. 2013 Producción y Consumo de Plata en la Península Ibérica. Un Análisis Comparativo entre la Sociedad Argárica y los Primeros Asentamientos Orientalizantes, Unpublished PhD thesis, Universidad de Granada, Granada.
Murillo-Barroso, M., Montero-Ruiz, I. and Aranda Jiménez, G. 2015 'An insight into the organisation of metal production in the Argaric society', Journal of Archaeological Science: Reports 2, 141-55. https://doi.org/10.1016/j.jasrep.2015.01.010
Murillo-Barroso, M., Montero-Ruiz, I., Rafel, N., Hunt Ortiz, M.A. and Armada, X-L. 2016 'The macro-regional scale of silver production in Iberia during the first millennium BCE in the context of Mediterranean contacts', Oxford Journal of Archaeology 35, 75-100. https://doi.org/10.1111/ojoa.12079
Pawlowsky-Glahn, V. and Buccianti, A. (eds) 2011 Compositional Data Analysis: Theory and Applications, London: Wiley. https://doi.org/10.1002/9781119976462
Percy, J. 1870 The Metallurgy of Lead, Including Desilverization and Cupellation, London: John Murray.
Pernicka, E. and Bachmann, H.G. 1983 'Archäometallurgische Untersuchungen zur antiken Silbergewinnung in Laurion: III. Das Verhalten einiger Spurenelemente beim Abtreiben des Bleis', Erzmetall 36, 592-97.
Pernicka, E., Lutz, J. and Stollner, T. 2016 'Bronze Age copper produced at Mitterberg, Austria, and its distribution', Archaeologia Austriaca 100, 19-55. https://doi.org/10.1553/archaeologia100s19
Perreault, C. 2019 The Quality of the Archaeological Record, Chicago: University of Chicago Press. https://doi.org/10.7208/chicago/9780226631011.001.0001
Ponting, M. 2018 'Pretia Victoriae or just an occasional bonus? Analysis of Iron Age lead artefacts from the Somerset Lake Villages', Oxford Journal of Archaeology 37, 185-99. https://doi.org/10.1111/ojoa.12137
Ponting, M. and Butcher, K. 2015 Analysis of Roman Silver Coins, Augustus to the Reform of Trajan (27 BC-AD 100) [data-set], York: Archaeology Data Service [distributor]. https://doi.org/10.5284/1035238
R Core Team 2020 'R: a language and environment for statistical computing', R Foundation for Statistical Computing. Vienna, Austria. https://www.R-project.org/
Renzi, M., Hauptmann, A. and Rovira, S. 2007 'Phoenician metallurgical production at SE-Spain', Proceedings of the 2nd International Conference 'Archaeometallurgy in Europe 2007', Grado-Aquileia. https://doi.org/10.1007/978-3-540-72238-0
Rothenberg, B. and Blanco-Freijeiro, A. 1981 Studies in Ancient Mining and Metallurgy in South-West Spain: Explorations and Excavations in the Province of Huelva, London: The Institute of Archaeo-Metallurgical Studies.
Salkield, L.U. 1982 'The Roman and pre-Roman slags at Rio Tinto Spain' in T.A. Wertime and S.F. Wertime (eds) Early Pyrotechnology: The evolution of the first fire-using industries, Washington DC: Smithsonian Institution Press. 137-147.
Salkield, L.U. 1987 A Technical History of the Rio Tinto Mines: some notes on exploitation from pre-Phoenician times to the 1950s, London: The Institute of Mining and Metallurgy. https://doi.org/10.1007/978-94-009-3377-4
Sisco, A.G. and Smith, C.S. 1951 Erker's Treatise on Ores and Assaying, Chicago, Illinois: University of Chicago Press.
Stahl, A. 2000 Zecca. The Mint of Venice in the Middle Ages, Baltimore and London: Johns Hopkins University Press.
Termeer, M.K. 2015 '3 Minting Apart Together: Bronze Coinage Production in Campania and Beyond in the Third Century bc' in S. Roselaar (ed) Processes of Cultural Change and Integration in the Roman World, Leiden, The Netherlands: Brill. 58-77. https://doi.org/10.1163/9789004294554_005 [Last accessed: 7 March 2023]
Trincherini, P., Domergue, C., Manteca, I., Nesta, A. and Quarati, P. 2009 'The identification of lead ingots from the Roman mines of Cartagena: the role of lead isotope analysis', Journal of Roman Archaeology 22, 123-45. https://doi.org/10.1017/S1047759400020626
Vaxevanopoulos, M., Davis, G., Milot, J., Blichert-Toft, J., Malod-Dognin, C. and Albarède, F. 2022 'Narrowing provenance for ancient Greek silver coins using Ag isotopes and Sb contents of potential ores', Journal of Archaeological Science 145, 105645. https://doi.org/10.1016/j.jas.2022.105645
Walton, M. and Trentelman, K. 2009 'Romano-Egyptian red lead pigment, a subsidiary commodity of Spanish silver mining and refinement', Archaeometry 51, 845-60. https://doi.org/10.1111/j.1475-4754.2008.00440.x
Wells, P.S. 2003 The Battle That Stopped Rome, New York: W.W. Norton & Company.
Willies L. 1997 'Roman mining at Rio Tinto, Huelva, Spain', The Bulletin of the Peak District Mines Historical Society 13, 1-29.
Wilson, A. 2012 'Raw materials and energy' in W. Scheidel (ed) The Cambridge Companion to the Roman Economy, Cambridge: Cambridge University Press. 133-55. https://doi.org/10.1017/CCO9781139030199.010
Wood, J.R. 2019 The Transmission of Silver and Silver Extraction Technology across the Mediterranean in Late Prehistory: An Archaeological Science Approach to Investigating the Westward Expansion of the Phoenicians, Unpublished PhD thesis, University College London (UCL). https://discovery.ucl.ac.uk/id/eprint/10070018/
Wood, J.R. 2022 'Approaches to interrogate the erased histories of recycled archaeological objects', Archaeometry 64(S1), 187-205. https://doi.org/10.1111/arcm.12756
Wood, J.R. 2023 'Identifying episodes of recycling in the archaeological record' in I. Bavuso, G. Furlan, E.E. Intagliata and J. Steding (eds) Economic Circularity in the Roman and Early Medieval Worlds: New perspectives on invisible agents and dynamics, Oxbow Books.
Wood, J.R. and Greenacre, M. 2021 'Making the most of expert knowledge to analyse archaeological data: a case study on Parthian and Sasanian glazed pottery', Archaeological and Anthropological Sciences 13, 110. https://doi.org/10.1007/s12520-021-01341-0
Wood, J.R. and Liu, Y. 2023 'A multivariate approach to investigate metallurgical technology: the case of the Chinese ritual bronzes', Journal of Archaeological Method and Theory 30, 707-756. https://doi.org/10.1007/s10816-022-09572-8
Wood, J.R. and Montero-Ruiz, I. 2019 'Semi-refined silver for the silversmiths of the Iron Age Mediterranean: a mechanism for the elusiveness of Iberian silver', Trabajos de Prehistoria 76, 272-85. https://doi.org/10.3989/tp.2019.12237
Wood, J.R., Charlton, M.J., Murillo-Barroso, M. and Martinón-Torres, M. 2017 'Iridium to provenance ancient silver', Journal of Archaeological Science 81, 1-12. https://doi.org/10.1016/j.jas.2017.03.002
Wood, J.R., Montero-Ruiz, I. and Martinón-Torres, M. 2019 'From Iberia to the Southern Levant: the movement of silver across the Mediterranean in the Early Iron Age', Journal of World Prehistory 32, 1-31. https://doi.org/10.1007/s10963-018-09128-3
Wood, J.R., Hsu, Y.-T. and Bell, C. 2021 'Sending Laurion back to the future: Bronze Age silver and source of confusion', Internet Archaeology 56. https://doi.org/10.11141/ia.56.9
Woytek, B.E. 2020 'Metal and system in Roman Imperial mints. Flan production, quality control and internal organisation of minting establishments during the Principate' in K. Butcher (ed) Debasement. Manipulation of Coin Standards in Pre-Modern Monetary Systems, Oxford: Oxbow Books. 125-42. https://doi.org/10.2307/j.ctv138wssp.14
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