Data from : Efficiency of Portable X-ray Fluorescence for Distinguishing Lead Slag

In the Minier Valley (France, Aveyron), an archaeological site excavation has led to the discovery of 25 kg of lead (Pb) slag, found in a secondary position. On a macroscopic level, these slags can be classified into two distinct categories, vitreous black and porous gray. This clear visual differentiation has been previously documented at other Pb–silver (Ag) metallurgy sites dating from the 12th century to the 14th century in Europe, and more particularly in the workshops of Mont Lozère, located approximately 80 km away from Le Minier. However, to date, scant evidence exists regarding the specific metallurgical process that produced this slag. This study presents the results of the analysis of 218 Pb slags (Supplemental Material) using portable X-ray fluorescence (pXRF). This method does not appear to be ideally suited for investigating this type of artifact, as it does not provide quantification of oxygen content. Nevertheless, it can be used to quickly identify trends and determine whether the two identified facies exhibit dissimilar chemical compositions. The results indicate that, based on the elemental compositions of the slags, no discernible distinction can be made to categorize them into two separate groups, both in bivariate and multivariate analyses. Consequently, it can be inferred that the gray and black slags originate from a single process executed within the same type of furnace. Scanning electron microscopy energy dispersive spectrometry analyses on selected samples demonstrate that variations in metal content are considerably exaggerated by pXRF, but that the trends observed are confirmed. The use of pXRF is therefore a relevant tool for determining whether or not Pb–Ag slag is the result of the same process. However, this initial approach needs to be refined by other analyses to confirm whether the smelted ores are of local origin and to be able to better define the details of the metallurgical process used.在法国阿韦龙省米尼耶山谷（Minier Valley）的一处考古遗址发掘中，出土了25千克铅（Pb）炉渣，该炉渣处于次生堆积位置。从宏观层面来看，这些炉渣可分为两类截然不同的品类：玻璃质黑色炉渣与多孔灰色炉渣。这种清晰的视觉区分特征，此前在欧洲12至14世纪的其他铅银（Pb-Ag）冶金遗址中已有记载，尤其是在距离米尼耶约80公里的洛泽尔山（Mont Lozère）冶炼作坊遗址中。然而截至目前，关于产出该炉渣的具体冶金工艺，相关证据仍十分匮乏。本研究展示了采用便携式X射线荧光光谱仪（portable X-ray fluorescence, pXRF）对218件铅炉渣（详见补充材料）开展分析的结果。该方法似乎并非研究这类考古遗存的最优选择，因为其无法对氧含量进行定量分析。但该方法可用于快速识别元素分布趋势，并判断已识别的两类岩相是否存在化学成分差异。分析结果显示，基于炉渣的元素组成，无论是二元变量分析还是多元变量分析，均无法将其明确区分为两个独立类别。因此可以推断，灰色与黑色炉渣均源自同一类熔炉内的同一冶炼工艺。对选定样品开展的扫描电子显微镜-能量色散X射线光谱（scanning electron microscopy energy dispersive spectrometry, SEM-EDS）分析结果表明，pXRF对金属含量变化的检测存在明显夸大，但所观测到的趋势仍得到了验证。因此，pXRF可作为判断铅银炉渣是否源自同一冶炼工艺的有效工具。但该初步分析方法仍需结合其他分析手段加以完善，以验证冶炼矿石是否产自当地，并更精准地明确所采用冶金工艺的具体细节。