The magnetic sourcing of obsidian samples from Mediterranean and near Eastern sources

The magnetic properties of obsidians are examined for their potential in sourcing obsidian artifacts. The three simplest to determine magnetic parameters—initial intensity of magnetization, saturation magnetization and low field susceptibility—are found to be effective discriminants of many Mediterranean, Central European and near Eastern sources. Although the between-source precision is not as good as geochemical analyses of minor and rare-earth elements, the technique demonstrated the existence of new sources that were subsequently confirmed by minor element analyses. Unfortunately some key sources do not appear to be readily distinguishable on these three simple magnetic parameters alone, although more sophisticated magnetic analyses may prove diagnostic. Despite this, it would appear that effective discrimination can be made in many cases, occasionally with more precision than minor element analyses. This technique therefore offers, as a minimum, a preliminary sourcing tool for use in many areas of the world, thus reducing the number of expensive geochemical analyses. Furthermore, its very low cost, non-destructive nature and speed open the possibility of quantitative evaluation of trade routes based on obsidian distributions, particularly as versions of the equipment are now suitable for use in the field.