Inyoite was found as fissure fillings in calcium borate minerals, which occur as an irregularly shaped body in the crystalline limestone near the gehlenite-spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. Inyoite occurs as aggregates of tabular crystals up to 1 mm wide, and rarely as euhedral crystals up to 0.5 mm wide in fissures of calcium borate minerals such as nifontovite, pentahydroborite, sibirskite and parasibirskite. The fissure fillings are composed only of inyoite. This is the first finding of inyoite in Japan. The type of occurrence is also different from those in many other localities in the world. Electron microprobe and CHNS / O analyses gave the empirical formula Ca1.99B5.96O5.92(OH)10·8.08H2O on the basis of O = 24. The unit cell parameters are a = 10.616(2), b = 12.068(1), c = 8.404(1) Å and β = 114.01(1)°. The mineral is optically biaxial negative with refractive indices α = 1.492, β = 1.506 and γ = 1.517, giving a calculated 2V = 82°. The Vickers microhardness is 91 kg mm−2 (10 g load) and the Mohs hardness number is 2.5. The measured density is 1.875 g cm−3. It is likely that the inyoite at the Fuka mine was formed by a reaction of ground water with calcium borate minerals at a temperature of around 20°C.
Numanoite, the Cu analogue of borcarite, is found in an irregular patch in crystalline limestone near gehlenite–spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. Numanoite (up to 1 mm across) is observed as a core or zones in borcarite crystals up to 5 mm long. The mineral is also found as veinlets up to 0.4 mm wide in aggregates of borcarite crystals. The associated minerals are nifontovite, bultfonteinite, calcite and an unidentified magnesium silicate mineral. In hand specimen, the mineral is blue-green to colorless and transparent with a vitreous luster. The streak is white to pale blue-green. Numanoite is monoclinic, space group C 2/ m , a 17.794(2), b 8.381(1), c 4.4494(7) A, β 102.42(2)° and Z = 2. The strongest seven lines in the X-ray powder-diffraction pattern [ d in A( I )( hkl )] are 7.57(100)(110), 2.671(84)(421), 2.727(68)(221), 1.887(52)(041,440), 2.272(48)(331), 2.899(44)(600) and 1.698(34)(640). Electron-microprobe and thermogravimetric analyses gave B 2 O 3 24.09, CaO 38.11, CuO 10.32, MgO 1.02, ZnO 0.51, CO 2 15.80, H 2 O 9.75, sum 99.60 wt.%. The empirical formula, calculated on the basis of O = 18, is Ca 3.898 (Cu 0.744 Mg 0.145 Zn 0.036 ) ∑0.925 B 3.969 O 5.615 (OH) 6.208 (CO 3 ) 2.059 , ideally Ca 4 CuB 4 O 6 (OH) 6 (CO 3 ) 2 . The mineral is optically biaxial negative, α 1.618(2), β 1.658(2), γ 1.672(2), and 2 V calc = 60°. The mineral has perfect cleavages in two directions. The density is 2.96(2) g/cm 3 (meas.) and 2.93 g/cm 3 (calc.). The Vickers microhardness is 376 (290–464) kg/mm 2 (25 g load), and the Mohs hardness number is 4½. The differential thermal analysis curve shows two endothermic peaks at 489° and 692°C. It is likely that numanoite from the Fuka mine formed by precipitation from late Cu- and Mg-bearing hydrothermal solutions.
Phase relation in the NaAlSiO 4 -SiO 2 -H 2 O system for the hydrothermal precipitation of jadeite, albite, natrolite, and analcime in jadeitite of the Itoigawa-Omi area, Japan ･････････････････････････････････････････Atsushi GOTO, Keitaro KUNUGIZA, Hiroshi MIYAJIMA ･･････ 271 Chemical composition of fluid inclusions in the Yorii jadeite-quartz rocks from the Kanto Mountains, Japan ･･････････････････････Mayuko FUKUYAMA, Tatsuhiko KAWAMOTO, Masatsugu OGASAWARA ･･････ 281 Cathodoluminescence petrography of P-type jadeitites from the New Idria serpentinite body, California
Fedorovskite was found as aggregates in crystalline limestone associated with gehlenite–spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. Fedorovskite occurs as gray to dark gray aggregates of anhedral translucent crystals up to 0.8 mm across in association with shimazakiite, uralborite, vimsite, cuspidine, fluorite, and calcite. An electron microprobe analysis of fedorovskite gave an empirical formula Ca2.013(Mg1.901Fe0.072Mn0.023Zn0.002Co0.001Ni0.001)Σ2.000(B3.852Si0.104)Σ3.956O7.000(OH5.421F0.579)Σ6.000 based on O = 7 and OH + F = 6. The mineral is orthorhombic, and the unit cell parameters refined from X–ray diffraction are a = 8.915(7), b = 13.086(16), c = 8.295(9) Å, and V = 967.7(18) Å3. The calculated density is 2.692 g cm−3. The fedorovskite from the Fuka mine was probably formed as a secondary mineral from calcium borates such as shimazakiite in a reaction with magnesium–bearing late hydrothermal solution.
Kurchatovite occurs as colorless granular crystals up to 1 mm at the Fuka mine, Okayama Prefecture, Japan. The mineral is associated with shimazakiite, calcite and johnbaumite. The Vickers microhardness is 441 kg mm−2 (50 g load), corresponding to 4½ on the Mohs' scale. The calculated density is 3.23 g cm−3. Electron microprobe analyses of kurchatovite gave empirical formulae ranging from Ca0.987(Mg1.004Fe0.020Mn0.001)Σ1.025B1.992O5 to Ca0.992(Mg0.466Fe0.523)Σ0.989B2.013O5 based on O = 5, and kurchatovite forms a continuous solid solution in this range. The mineral is orthorhombic, Pbca, and the unit cell parameters refined from XRD data measured by a Gandolfi camera are a = 36.33(14), b = 11.204(3), c = 5.502(17) Å, V = 2239(12) Å3. It is formed by a layer of MgO6–octahedra, a layer of CaO7–polyhedral and B2O5 consisting of two BO3–triangles. The kurchatovite from the Fuka mine was probably formed by supplying Mg and Fe to shimazakiite from hydrothermal solution at a temperature between 250 to 400 °C.
Calciborite was found as a veinlet or a mass in crystalline limestone associated with gehlenite-spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. Calciborite occurs as milky white aggregates up to 1 mm in diameter with shimazakiite, fluorite, bornite and calcite. An electron microprobe analysis of calciborite gave an empirical formula (Ca0.999Mn0.001Co0.001)Σ1.001B1.999O4 based on O = 4. The unit cell parameters are a = 8.373(2), b = 13.811(8), c = 5.012(4) Å. The mineral is optically biaxial (-), α = 1.594(2), β = 1.654(2), γ = 1.672(2) and 2Vcalc. = 56°. The Vickers microhardness is 177 kg mm-2 (50 g load), and the Mohs hardness number is 3.5. The measured and calculated densities are 2.88(2) and 2.881 g cm-3, respectively. The calciborite from the Fuka mine was probably formed by a reaction of boron-bearing fluids with limestone at a temperature between 250 and 300 °C.
Zálesíite is found to exist as hexagonal prismatic crystals (length: up to 1 mm; width: 10 μm) and fibrous aggregates in the alteration zone in crystalline limestone near gehlenite-spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. The mineral is pale green to emerald green in color with a silky to vitreous luster. Andradite, aragonite, bornite, cahnite, chalcocite, chalcopyrite, conichalcite, johnbaumite, and an unidentified Ca-Cu arsenate mineral coexist in the abovementioned limestone. From SEM-EDS analysis, the empirical formula of zálesíite is found to be (Ca0.74Bi0.26)Σ1.00(Cu5.80Ca0.18Ni0.01Zn0.01)Σ6.00[(As2.86Si0.12P0.02)Σ3.00(O11.14OH0.86)Σ12.00](OH)6·3H2O on the basis of the following calculation: 10 (M1 + M2 + X) + 6 (OH) + 3 (H2O). Zálesíite collected from the Fuka mine contains Bi and is free of REE. The unit cell parameters of the zálesíite crystals are a = 13.656(9), c = 5.850(4) Å, V = 945(1) Å3, and Z = 2. It is inferred that zálesíite is formed by the reaction between crystalline limestone, cahnite, johnbaumite, Cu sulfide, and a Bi-rich hydrothermal solution.
Talmessite was found in veinlets (approximately 1 mm wide) cutting into massive limonite in the oxidized zone of the Uriya deposit, Kiura mining area, Oita Prefecture, Japan. It occurs as aggregates of granular crystals up to 10 μm in diameter and as botryoidal aggregates up to 0.5 mm in diameter, in association with arseniosiderite, and aragonite. The talmessite is white to colorless, transparent, and has a vitreous luster. The unit-cell parameters refined from powder X-ray diffraction patterns are a = 5.905(3), b = 6.989(3), c = 5.567(4) Å, α = 96.99(3), β = 108.97(4), γ = 108.15(4)°, and Z = 1. Electron microprobe analyses gave the empirical formula Ca2.15(Mg0.84Mn0.05Zn0.02Fe0.01Co0.01Ni0.01)∑0.94(AsO4)1.91·2H2O on the basis of total cations = 5 apfu (water content calculated as 2 H2O pfu). It is suggested that the talmessite formed as a secondary mineral derived from löllingite, calcite, and diopside.
