Vimsite from the Fuka mine, Takahashi, Okayama, Japan

Abstract

Vimsite, CaB₂O₂(OH)₄, was found in near the boundary between crystalline limestone and aggregate of borate minerals, which consist mainly shimazakiite, priceite, uralborite, calciborite, kurchatovite, at the Fuka mine, Okayama, Japan. Vimsite was first described as a new mineral by Shashkin et al. (1968) from Ural, Rusia. This is the first report of vimsite in Japan. EPMA gave the empirical formula (Ca_0.992Mg_0.009Fe_0.003Mn_0.001)_Σ1.005 B_1.995 O_1.993 (OH)_4.007 on the basis of O=6. The unit cell parameters area=10.021(10), b=4.434(7), c=9.618(15)A,β=91.205(2)°.