Microprobe analyses of olivine crystals (percent forsterite) in lava from the ongoing Puu Oo eruption of Kilauea Volcano, Hawaii (1983 to present) plotted against whole rock Mg#. Solid circles are phenocrysts; horizontal lines are microphenocrysts. Most olivines plot in the field of equilibrium defined by Mg KD=0.30 (Roedder & Emslie, 1989). Many lavas have olivine with forsterite contents of 85%, which probably grew in liquid of about 10 wt% MgO. The arrow indicates the probable effect of olivine accumulation, which may have occurred in some of the 1990 lavas. (From: Garcia et. al., Bull. Volc., in review)

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