In contrast, the 1959 scoria sample has b1% of olivine phenocrysts (Table 1), the lowest among the analyzed tephra, consistent with having the lowest bulkrock MgO content (Table 2). The observed olivine microphenocrysts are fragmented and typically have convoluted and resorbed margins, with compositions similar to those for the 1954 scoriae. Clinopyroxene crystals are compositionally zoned, subhedral to euhedral in form, and rich in opaque inclusions. Analyzed clinopyroxenes immediately adjacent olivines