MEDIEVAL LEAD MAKING ON MONT-LOZèRE MASSIF (CÉVENNES-FRANCE): TRACING ORE SOURCES USING PB ISOTOPES

Abstract

This study aims to document the origin of metallurgical activities on the Mont-Lozère Massif (Cévennes Mountains, South of Massif Central, France), which is the largest medieval site of Pb-Ag metallurgical activities in France. These activities are characterised by more than 70 sites comprising numerous dispersed slags. Related charcoal samples dated by 14C have yielded a medieval, ca. XI-XII th. C. age. Numerous ore deposits, now mostly old mine tailings, surround the granitic massif and are possible candidates for suppliers of the old smelting activities. In Western Europe, Pb-Ag mines were of primordial importance for the medieval monetary system. Mines were intensively coveted by Lords, Bishops and Kings, and their exploitation was strictly regulated by each owner. The scarcity of ancient manuscripts makes it impossible to use a historical approach to determine the ore source regions related to a given metallurgical activity. The ore sources for this metallurgical activity were traced by comparing the Pb isotopic composition of slags and that of galena deposits surrounding the Mont-Lozère. The range of Pb isotopic compositions measured in slag samples is restricted and included in the field defined by galena from surrounding ores in Pb-Pb isotope diagrams. It is shown that, although direct tracing of the ore supplies is not straightforward, many ancient mine areas must be excluded, whereas some others seem highly likely. These old mines are not necessarily the closest to the smelting sites, suggesting that the choice of metal making location was constrained by several factors, including type of wood (here beech) and water proximity, but more importantly land ownership. © 2005 Elsevier Ltd. All rights reserved.