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Appendix: Supplementary Information

I. Methods and materials

A. Sampling and the generation of raw data

The samples were collected from the artefacts using either a drill bit or a jeweller's saw, according to the dictates of each object's shape. Drilled samples were preferred, constitute the majority of samples collected, and typically weighed 1g or less. Small objects were targeted for sampling, with the assumption that larger objects were more likely to have been made of metal derived from more than one source. Both the drilled and sectioned samples were submitted to Z.A. Stos-Gale of the Isotrace Laboratory of Oxford University for analyses of bulk elemental composition by ED XRF, and lead isotope analysis using Thermal Ionization Mass Spectrometry (TIMS), with overall accuracy of better than ±0.1%.

B. Interpretations of lead isotope data

Provenance studies based on lead isotope analyses rely on the measurements of each artefact's independent and stable isotope ratios ²⁰⁸Pb/²⁰⁶Pb, ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁶Pb/²⁰⁴Pb, and their comparison to ores characterised by the same measurements. Using artefact data generated by thermal ionization mass spectrometry (TIMS) with a reported overall accuracy of better than ±0.1% per atomic mass unit, and based on absolute values for all recorded ratios, we detail consistencies between artefact and ore ratios (Table 2) where all three are identified within a percentage difference of 0.2% or less. This percentage difference is used to identify the ore data that will cluster with or near our artefact data on the bi-plots. Consistencies established with a percentage difference of 0.1% or less represent effectively identical data (and appear in green). The same formula, dx = 100 * (x2 - x1)/((x2 + x1)/2)), is applied to each of the three lead isotope ratios. Note that Boni and Koeppel (1985) reported ore data with error margins of 1% and 2%. Because the intention of identifying a singular, 'real' origin from among these matches for each artefact is too often unrealistic, we document ranges of arguable possibilities to make them available to non-specialists who may wish to build cases in view of them. Biplots here emphasize overlaps in characterized lead ores to provide insight into the complexities of using lead isotope data to address the Phoenician Question.

C. Materials considered

In this article we focus on the Phoenician Question from the perspective of silver. Other archaeological materials, that are often difficult to date and interpret with desired precision, have long suggested links to trans-Mediterranean, pre-colonial trade. These are updated in Demand (2011, 220-55). We have defined frequency specific metallic sequencing here as it applies to the study of hoards, but note that the method might as well apply to other sealed contexts like graves and shipwrecks, with adaptations to the research questions.

II. On-line updates

Readers interested in the on-going reporting of consistencies established between our artefact samples and an expanding body of comparative data are referred to the research of the Hacksilber Project presented on Open Context. There, the consistencies will be documented in a stable, citable format archived with the California Digital Library.

III. On the origin and structure of the sample set

The collection of the sample set was among Thompson's work as part of the Hacksilber Project, which was organised by the late Miriam S. Balmuth during the 1990s, and conceived and initiated with Thompson (Balmuth and Thompson 2000; Thompson 2004). The Project had an earlier foundation in Balmuth's unpublished doctoral dissertation at Harvard University in the 1960s, which involved the cataloguing of metal hoards and early coinage found throughout the ancient Near East and eastern Mediterranean. Thompson's research on silver, in particular, began with the study of the Shechem Hoard at CMRAE at the Massachusetts Institute of Technology for a Master's thesis, and would build from there. The Hacksilber Project's initial phase of research also resulted in the publication of papers by scholars who were invited to contribute from their expertise in a variety of materials and methods to the subject of the transition from hacksilber to coinage (Balmuth 2001). At the same time, project funding raised by Balmuth and Thompson supported some of the research leading to the identification of the Cisjordan Corpus of Iron Age hacksilber hoards (Thompson 2003), upon which the present study is directly founded.

Thompson examined hoards and sought samples (often unsuccessfully) from objects in museums and storage facilities around the eastern Mediterranean, Europe and the United States for five years, which led to the gradual identification of the Corpus of silver-dominant hoards in Iron Age Cisjordan (some of the hoards in the Corpus had been tentatively and mistakenly characterised elsewhere as 'mixed metal hoards' or containing mixed quantities of bronze, gold and electrum). Because of the generosity and professionalism of the Israel Antiquities Authority, the Israel Museum and excavators, it was possible to locate and sample most of the hoards that would eventually be organised into the Corpus. For reasons ranging from accessibility and accident to deliberate choice, and with Balmuth's support and advice to sample as much as possible from wherever samples could be obtained, the sample set was eventually constructed to focus chiefly on silver in Cisjordan datable to between 1200–586 BC, with additions of samples from earlier hacksilber and later coin hoards where possible.

All of the hoards included in the Cisjordan Corpus contain dominant quantities of silver to the near or complete exclusion of other metals, usually in the form of hacksilber (broken and minimally decorated jewellery, sheet metal, ingots and varia). The original catalogue listed 34 hoards found at 13 sites (Thompson 2003), and continues to grow as relevant material is recognised. Here, Wadi el-Makkuk (Sass 2002) is added, and three bundles are now counted for Beth Shean D (Thompson 2009). A couple of silver hoards occur in Bronze Age contexts in Cisjordan (Thompson 2003), but we do not include, for example, fragmented finds of silver from Middle Bronze Age Nahariya (Dothan 1956). While there is a clear emphasis on silver at Nahariya at that time, the scrap there has industry-specific forms related to figurine production, and characteristics of silver that may have been alloyed with far more than 3 or 4% copper.

IV. Additional notes concerning provenance studies

A. Hacksilber from Tel Miqne-Ekron

In general, the sub-region of Philistia within Cisjordan is relatively lacking in silver between c. 1100 and 800, which may reflect its lack of interest in the material, or its inability to obtain and accumulate this metal. When silver does appear in quantity at Tel Miqne-Ekron in the 7th century, the ore signatures of the great majority of sampled artefacts have ratios consistent with the Aegean ores at Laurion (Figure 4). This suggests direct connectivity, or limited mediation between the source of the material and its deposition, as well as recent accumulation prior to deposition. The high percentage of sampled objects in the hoards from Ein Hofez that have lead isotope ratios consistent with Sardinian and Iberian derivation seem also to suggest a relatively recent influx prior to deposition. The potential of this material to suggest connections to the Sea Peoples tribe known as the Sherden (Thompson 2011), and to reflect the kind of connectivity between Sardinia and Iberia remembered in the legend of Norace (Paus. 10.17.5), must be discussed in light of the more detailed elemental analyses of our samples.

B. Hacksilber from Arad and Eshtemoa

The site of Arad lies just west of the Dead Sea in the northern Negev. The 203g hacksilber hoard from there dates to the 10th century, but could not be located in storage for several years, when requests were made for examination and sampling. Five jars found at Eshtemoa in today's West Bank contain 26kg of hacksilber, making it by far the largest in the Corpus. It might well belong to the same period as the material from Arad (proposed and necessarily uncertain dates range between the 12th and 8th centuries). Figure 6 shows several of our samples plotting generally with the range of older western Mediterranean ores discussed in this article. The detailed interpretations belong to another context.

Figure 6: Selected western Mediterranean lead ores (24-34) versus samples from the Eshtemoa Hoard. See key for numbered citations.

V. Chronological points

A. The use of dates

Within the text, we use dates to refer to periods as if they were firmly established and definitively demarcated blocks of time. This is a matter of convention and convenience. Trends developed across temporal boundaries. In particular, the evidence for trade in silver (and lead) with the west in Iron Age Phoenicia appears to be an inflection of patterns in connectivity established before 1200 BC (Thompson 2011).

B. Hacksilber from Akko

The stratigraphy of Area A at Akko has never been fully developed; the initial dates assigned to the juglets associated with the hacksilber (9th-8th century, see Thompson 2003, with references), were based on preliminary and inconclusive field readings. The juglets date typologically anywhere between the 10th-7th centuries, and suggest a date range for the hacksilber hoard beginning from the 10th century (A.J. Brody, personal communication).

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