Absorption of iron by platinum capsules in high pressure rock melting experiments

Samples of hornblende eclogite (olivine basanite composition), containing 0.38 wt percent H_2O bound in amphibole, were sealed in Pt capsules, held above the liquidus at 1250°C, 10 kbar, in 1/2-inch piston-cylinder apparatus for various time periods, and then sectioned for microprobe analyses. The resultant liquids lost about half of their initial 14 wt percent FeO (total Fe as FeO) to the Pt capsule during an experiment of only thirty minutes duration, and lost 97 percent during a run lasting four hours. This rate is significantly greater than rates of iron loss reported previously, and can affect significantly the interpretation of experimental results in high temperature studies of basaltic and periodotitic compositions.