Characterization and identification of minerals in rocks by ToF-SIMS and principal component analysis

Abstract

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to characterize and identify minerals in rock samples. ToF-SIMS provides a vast amount of information due to the recording of complete mass spectra with elemental and molecular ion signals. For an efficient handling of this amount of data multivariate analysis (MVA) techniques are useful tools. Initially principal component analysis (PCA) was implemented to classify 20 well-defined reference minerals. In a second step the spectra data of undetermined minerals in rock samples were projected on the PCA models to identify these mineral species. Hereby the data sets of positive and negative ion signals were used separately. It was possible to classify the reference minerals and identify mineral species in rock samples. Furthermore it was found that minerals not contained in the reference set were not misidentified.