%0 Journal Article %T A general equation for estimating Fe3+ concentrations in ferromagnesian silicates and oxides from microprobe analyses, using stoichiometric criteria %A Droop, G. T. R. %A , %J Mineralogical Magazine %V 51 %N 361 %P 431-435 %@ 0026-461X %D 1987-09-01 %I Mineralogical Society %~ DeepDyve