Piemontite from the manganiferous hematite ore deposits in the Tokoro Belt, Hokkaido, Japan

Hydrothermal syntheses of epidote and piemontites on the join Ca2Al2Fe3+Si3O12(OH)-Ca2Al2Mn3+Si3O12(OH) at relatively low pressures of 200-400 MPa

“…Whereas the results of the present study and those of Akasaka et al (2003) Epidote tends to occur in metamorphic rocks and hydrothermally altered rocks as well formed crystals over a few millimeters in length, but piemontite crystals are generally less than 1 mm long (e.g., Akasaka et al, 1988Akasaka et al, , 1993. In the syntheses carried out here, large Mn 3+ free epidote crystals formed (Fig.…”

“…3c) are also composed of fine crystals. Such features have been reported from piemontite in manganiferous iron ore deposits which underwent low grade metamorphism (Akasaka et al, 1988).…”

Manganese formations in the accretionary belts of Japan: Implications for subduction–accretion process in an active convergent margin

“…The manganiferous iron ores of the Kokuriki mine (No. 1) consist mainly of hematite and quartz with accessories of bixbyite, piemontite, Mn 2+ -pumpellyite, okhotskite, neotocite, bementite, fluorapatite, inesite, barite and rhodochrosite (Togari and Akasaka, 1987;Akasaka et al, 1988). By the geochemical studies of Choi and Hariya (1992), the iron -manganese deposits were considered to have formed by precipitation from submarine hydrothermal solutions.…”

X-ray Rietveld and 57Fe M^|^ouml;ssbauer study of babingtonite from Kouragahana, Shimane Peninsula, Japan

“…Babingtonite in association with prehnite does not coexist with Fe -rich pumpellyite, and, as well as prehnite, is regarded to have crystallized at temperatures lower than that of Ferich pumpellyite. Pumpellyite crystallizes at temperatures below about 400 °C (Akasaka et al, 2003b) or 300 °C (Liou, 1973;Schiffman and Liou, 1983;Akasaka et al, 1988). Thus, the crystallization temperatures for babingtonite occurring in cavities (below 200 °C) proposed by Birch (1983) and Wise and Moller (1990) babingtonite Fe 2+ and Fe 3+ are ordered at the Fe1 and Fe2 sites, respectively.…”