Genesis of an anorthosite is evaluated by field, petrographic, emission spectrographic, and x-ray diffraction methods which confirm a volcanic origin. Zoning of plagioclase crystals suggests a complex intratelluric history oTrace element and modal analysis studies imply a positive correlation with high alumina-basalts. Cr/v ratios of .04 and Ba/Sr ratios of l o 70 indicate middle-stage fractionation. Origin from a primary anorthositic magma is precluded.
