The calibration curves for P2O5, MnO, and Fe2O3 are poorer, but we believe a major cause is the restricted range of MnO and Fe2O3 in the standard suite. The greater dispersion of data in the P2O5 calibration exercise is likely due to the low concentrations of this oxide in all five sample standards, resulting in poor counting statistics. Future work will include expanding the range of samples used to calibrate for these less concentrated elements.