Identification of mineral phases on basalt surfaces by imaging SIMS

A method for the identification of mineral phases on basalt surfaces utiliz ing secondary ion mass spectrometry (SIMS) with imaging capability is descr ibed. The goal of this work is to establish the use of imaging SIMS for cha racterization of the surface of basalt. The basalt surfaces were examined b y interrogating the intact basalt (heterogeneous mix of mineral phases) as well as mineral phases that have been separated from the basalt samples. Mi neral separates from the basalt were used to establish reference spectra fo r the specific mineral phases. Electron microprobe and X-ray photoelectron spectroscopy were used as supplemental techniques for providing additional characterization of the basalt. Mineral phases that make up the composition of the basalt were identified from single-ion images which were statistica lly grouped. The statistical grouping is performed by utilizing a program t hat employs a generalized learning vector quantization technique. Identific ation of the mineral phases on the basalt surface is achieved by comparing the mass spectra from the statistically grouped regions of the basalt to th e mass spectral results from the mineral separates. The results of this wor k illustrate the potential for using imaging SIMS to study adsorption chemi stry at the top surface of heterogeneous mineral samples.