Analyses were carried out on samples from 20 archaeological bipyramidal iron ingots from the Speyer depot in the Upper Rhine region, Germany, dated to the Hallstatt D and La Tène A periods (800–450 BCE). Typologically, the ingots belong to type BLS4 of bi-pointed ingots, consistent with their distribution in the Rhine and Moselle valleys. In addition, 40 iron ore samples were analysed; these were collected from iron ore deposits, former iron ore mines, and smelting sites in southern Germany. The aim of the analyses was to determine the geographic location and the isotopic and geochemical characteristics of the iron ore resources exploited during the Iron Age for the production of bipyramidal ingots. We aimed to obtain the most comprehensive possible provenance signature for each ingot sample by combining Re–Os isotope and concentration measurements with trace-element analyses. The signature preserved in an archaeological iron object largely reflects the isotopic and chemical characteristics of the ore smelted to produce the iron that was subsequently forged into the ingot. For the iron ingots, analyses were performed on bulk metal (Re–Os isotope analyses and ICP-MS trace-element analyses of the metallic matrix) and on polished sections (slag-inclusion analyses by LA-ICP-MS). Iron ores were analysed in bulk for Re–Os isotopes and as pressed pellets by LA-ICP-MS to determine whole-rock geochemical compositions. A further aim of the study was to evaluate the effectiveness of the Re–Os system for determining the provenance of archaeological iron. In addition, two AMS radiocarbon measurements were performed on metal from the ingots to determine their chronological timeframe of use. The iron ore dataset includes samples from southern Germany, specifically the Swabian Alb, the Danube valley in Bavarian Swabia, and the Black Forest massif. Many of these ore samples had previously been analysed only for Os isotopes within the CIPIA project (Dillmann et al., 2017, ESM 1). All analytical data were acquired at the laboratory of the Curt Engelhorn Centre for Archaeometry (Mannheim, Germany). The full description of the data and methods is provided in the data description file. The datasets are provided as six Microsoft Excel files.
This research was funded by the German Research Foundation (DFG project BR 4312/5-1, “Zum Verhalten der siderophilen Spurenelemente bei der Eisenherstellung”).