Green, grey and black: A comparative study of Sierra de las Navajas (Mexico) and Lipari (Italy) obsidians

Sierra de las Navajas obsidians show a significant chemical variability in terms of trace elements, that can be explained by common evolutionary processes in the magma chamber. However, this variability is also internal to a single volcanic complex and this makes the trace element contents unsuitable to differentiating between the different sub-sources of the same area. On Lipari, our data do not allow us to distinguish between the two sub-sources of Vallone del Gabellotto and Canneto Dentro on the basis of major and trace elements. On the whole, our study suggests that caution should be used for both Lipari and Sierra de las Navajas when identifying obsidian sub-sources on the basis of trace element contents.