Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for spatially resolved trace analysis of early-medieval archaeological iron finds

摘要

The suitability of laser ablation ICP-MS for minor and trace analysis of archaeological iron finds, pro- duced by a direct reduction process in a 'bloomery' fur- I nace, is reported, The analysis of elemental impurities in I the iron can provide useful archaeometallurgical information on the production process and the provenance. of the 1 iron. Since, even after refinement, the iron resulting from this process may contain many inclusions (slag, charcoal, I holes, etc..), a method should be used with sufficient spa- I tial resolution to preclude the inclusions from the analy- J sis. The ablation parameters are selected such that abla- I tion craters of approx. 100 I.1m in diameter are obtained. . The method is validated with low alloy steel and cast iron , standard reference materials and by a comparative analy- i sis with electron probe microanalysis (EPMA). The preci.. 1 sion is limited mainly by the homogeneity of the iron, ~ rather than by instrumental reproducibility. The advan- j tages and drawbacks of the method are briefly compared I with EPMA. Preliminary results from the analysis of ar- i chaeological iron samples from excavations at Develier- j Courtetelle (Canton Jura, CH), Neftenbach (Canton j Zurich, CH), Wartau (Canton St Gallen, CH) and Mont Chemin (Canton Valais, CH) are given.