Just a crush? Contamination of archaeological samples by different grinding media

A chert cobble from an archaeological quarry on southern Baffin Island, Canada, was divided and crushed using five different methods: i) agate mortar and pestle, ii) stainless steel shatterbox, iii) tungsten carbide shatterbox, iv) alumina ceramic shatterbox, and v) zirconia ceramic shatterbox. Powders produced by each method were submitted for acid digestion and analysis by inductively coupled plasma mass spectrometry. The trace element results indicate that different crushing media can contribute significant trace element contamination to chert during the grinding process. These results demonstrate the need for an informed approach to the selection of sample preparation methods when submitting archaeological samples for solution or pellet based geochemical analysis.