GEOPAC: a set of programs for on-line quantitative microprobe analysis of oxide-based specimens

A set of programs for on-line collection and quantitative reduction of microprobe data for oxide-based specimens which may contain up to 25 oxides was developed. The programs, written in the SANDIA-FOCAL language, control both spectrometer and stage motions in order to collect peak and background data in triads for a time sufficient to provide preset counting statistics. Values from intermediate triads are stored on disk until a complete data set has been collected; the data set is then reduced via a three-iteration Bence--Albee technique to stoichiometric oxides; and a summary of the composition and, where appropriate, a normative or endmember analysis are printed. Ninety-five percent confidence level limits are calculated and printed if more than one point has been analyzed