The identification of growth lines in abalone shell using a nuclear microprobe

Ionoluminescence (IL) combined with particle induced X-ray emission (PIXE) imaging has been employed to identify intrinsic growth bands in the spire region, and extrinsic bands at the growth edge of Australian Black-lip abalone shell (Haliotis rubra). Previous studies using optical flood cathodoluminescence, scanning electron microscope cathodoluminescence (SEM-CL) and Raman spectroscopy on samples from the same population suggest that the visible luminescence is due to Mn2+ activated calcium carbonate. In this study we confirm Mn2+ as the activator in both the spire and growth edge regions of the shell. The sensitivity of ionoluminescence to the co-ordination environment of the Mn2+ activators in the shell allows for the spatial identification of the calcium carbonate polymorph responsible for the growth lines observed optically. Furthermore the detection and mapping of trace elements such as Mn and Sr with the PIXE technique enables comparisons to be made between calcite and aragonite biomineralized in the wild and under laboratory conditions. (C) 1999 Elsevier Science B.V. All rights reserved.