ANALYSIS OF OXYGEN WITH THE ELECTRON-MICROPROBE - APPLICATIONS TO HYDRATED GLASS AND MINERALS

The development of layered synthetic dispersion elements makes it possible to analyze routinely for O with the electron microprobe. The precision for O in silicate glass is 0.6% of the amount present, comparable to that for Si. Optimum results occur when standards similar in composition to unknowns are used and care is taken in standard and sample preparation. The procedure is particularly advantageous in the analysis of hydrous glass and minerals in which conventional microprobe analyses yield totals of less than 100% because O attached to H remains unmeasured. The direct determination of O provides a measure of the quality of the analysis and yields an indirect estimate of the H2O content of the sample by comparison of measured with stoichiometric O concentrations.