Priceite from the Fuka mine, Okayama Prefecture, Japan

摘要

Priceite was found as a mass or a veinlet in crystalline limestone associated with gehlenite-spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. Priceite occurs as grayish white or pale green aggregates of anhedral or prismatic crystals up to 0.5 mm in length in association with shimazakiite, sibirskite, uralborite and calcite. An electron microprobe analysis of priceite gave an empirical formula (Ca2.023Mno.002Feo.001Mgo.001Nio.002 Co_(0.001))_(Σ2.030)B_(5.033)O_(7.160)(OH)_(4.840)·H_2O based on O = 13. The unit cell parameters are a = 11.633(7), b = 6.977(3), c = 12.342(5) A,β = 110.648(7)°. The calculated density is 2.486 g cm~(-3). It is likely that priceite from the Fuka mine was formed as a secondary mineral by a late-hydrothermal alteration of shimazakiite at temperature between 100 and 190 ℃ or less.