抄録
Henmilite was found in a calcite vein cutting gehlenite-spurrite skarns at Fuka, Okayama Prefecture. The mineral occurs as prismatic crystals up to 3 mm long. The occurrence is distinct from the type specimen originally described by Nakai et al. (1986); The associated minerals such as tenorite, sillenite, bultfonteinite, cuspidine and thaumasite are different from those by Nakai et al. (1986). The present paper reports on some new data on the mineralogical properties of henmilite, in addition to those reported by Nakai et al. (1986). New data on henmilite are as follows; (1) Henmilite has the forms {100}, {010}, {101}, {102}, {110} major and {011}, {142} minor. (2) The wet chemical analyses give B202 19.49, CaO 29.24, CuO 21.56, H2O(+) 29.57 and total 99.86 %, yielding the empirical formula on the basis of (O) =12 Ca1.991 Cu0.994 B2.052 O12H12.033. (3) The vickers microhardness is 193-206 kg/mm2 on ten identations (25 g load). (4) The density measured is 2.51 g/cm3. (5) The DTA curve has a strong endothermic peak at 237°C and a sharp exothermic peak at 589°C. (6) On heating the mineral at 900°C, tenorite (CuO) and calcium borate (Ca2B2O5) appear as crystalline phases.
