Generation of polygenetic olivine phenocrysts is discussed for a basanite from Okete Quarry, New Zealand, based on descriptions of its olivine and spinel and the reaction product between the basanite and its peridotite xenoliths. The olivine phenocrysts can be divided into two types, I and II. The phenocrysts (I) are relatively small, subhedral to euhedral and has minute spinel inclusions sparsely throughout the grain. They are free of the textures indicating deformation and fracture. The phenocrysts (II) are relatively large and have spinel inclusions only in the rim. Their core has deformation textures and/or fluid inclusion trails. The olivine phenocrysts (I) are normally zoned: the core ranges from Fo₈₅ to Fo₇₆ and the rim has Fo₇₆. The spinel inclusions are highly variable in Cr/(Cr+Al+Fe³⁺) atomic ratio (0.02-0.5), Cr# (=Cr/[Cr+Al] atomic ratio) (0.1-0.6), TiO₂ content (17-1 wt%) and Fe³⁺/(Cr+Al+Fe³⁺) atomic ratio (=Fe³⁺ ratio) (0.7-0.2), and can be grouped into two, low-Fe³⁺ (Fe³⁺ ratio <0.5) and high-Fe³⁺ (Fe³⁺ ratio >0.5) spinels. The Cr ratio is correlated positively with the Cr# and negatively with the TiO₂ content and Fe³⁺ ratio. The phenocrysts (II) frequently have compositionally flat cores, which are relatively Mg-rich (up to Fo₉₀), and zoned rims (Fo₈₅₋₇₆). Their spinel inclusions mostly belong to the high-Fe³⁺ group. The generation of olivine crystals and their spinel inclusions of various origins can be observed at the boundaries between the basanite and its peridotite xenoliths. Orthopyroxene in the peridotite xenoliths was decomposed into olivine, clinopyroxene, spinel and melt (glass) by the reaction with the basanite melt. The spinel from the reaction product is relatively high-Cr#. Subhedral olivine which includes chromian spinels with a wide compositional range has overgrown on the mantle olivine, which has been gradually disintegrated into the basanite matrix.
     The olivine phenocrysts (I) with low-Fe³⁺ spinel inclusions were derived from the orthopyroxene/melt reraction product, and those with high-Fe³⁺ spinels were precipitated from the basanite melt. The olivine phenocrysts (II) are of xenocrystal origin and have been modified by the melt to various degrees. The olivine phenocrysts in olivine-rich magmas such as picrite basalts and alkali olivine basalts can be polygenetic due to the reaction between the mantle peridotite and more primitive magmas.

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The mode of occurrences of gageite from manganese ore deposits in outer zone of the Southwest Japan were investigated. Twenty six occurrences of gageite, beside locations reported by Fukuoka and Hirowatari (1988) and Matsubara and Kato (1979), were newly found from high P/T type (pumpellyite-actinolite facies to zeolites facies) manganese ore deposits distributed in the southern and northern zone of Chichibu belt in the Kii Peninsular, Shikoku and Kyusyu district. Gageite occurs as a principal constituent mineral of altered braunite designated as chocolate ore, which is chocolate-colored massive ore composed of various minerals with high Mn content, locally as veinlets, and form tabular and fibrous crystals of 2-3 mm order in length. Two occurrences of gageite are distinguished. Gageite is commonly accompanied by rhodo-chrosite, alleghanyite and hausmannite with minor ribbeite, pyrochroite, kellyite, barite, cymrite, and sussexite. Gageite, also, occurs rarely as thin laminated layers with caryopilite in the banded rhodochrosite ore. EPMA analyses indicated that gageite is chemically characterized by low Mg content, however their Mg contents are generally larger than those in closely coexisting alleghanyite. The occurrence of gageite suggests that gageite in chocolate ore have been formed later than alleghanyite as an alteration products from braunite ore under the high f  H₂O condition. On the other hand, it is assumed that laminated gageite in rhodochrosite ore is primary mineral formed under the low grade regional metamorphism.

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