In situ spatial distribution mapping of radionuclides in minerals by nanoSIMS

The nanoSIMS (nanometre-resolution secondary ion mass spectrometry) microanalytical platform is used, for the first time, for direct in situ visualization of medium half-life radionuclide (RN) distributions (Ra-226 - 1602y; Pb-210 - 22.3y) in copper sulphide-bearing ore and copper sulphide flotation concentrate samples. More than 200 grains have been mapped, all with an Hyperion (H200) RF plasma oxygen ion source. Sufficient counts for masses of interest allowed the generation of maps that stand as a proof of concept for further detailed work to address the physical locations of radionuclides of main interest. The issue of potential isobaric interfering masses has been addressed and partially resolved. The distribution of the studied radionuclides, both in relation to host minerals and in relation to each other, is logical and clearly supported by well-established theories of deportment, diffusion, and redistribution. Isotope maps for (RN)-R-210 (Pb-210, Po-210 and Bi-210) and Ra-226 maps tended to show RN distribution either within minerals (evenly distributed or zoned), as 'hot spots' on grain surfaces/mineral boundaries, or between cleavage planes of micaceous minerals. NanoSIMS element mapping of radionuclides may have widespread application for the disposal and long-term storage of nuclear waste, radioisotope monitoring, forensic science, nuclear and materials science, nuclear medicine, minerals engineering, and isotope geochemistry.