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Ohnishi M.,12 43 Takehana Ougi cho | Tsuruta K.,Kyoto City University of Arts
Journal of Mineralogical and Petrological Sciences | Year: 2012

Secondary minerals of tungsten that are the products of alteration of scheelite present in quartz veins in the Ishidera area, Wazuka, Kyoto Prefecture, have been examined using XRD, SEM-EDS, EPMA, and XRF. From the results, three tungsten minerals were identified: anthoinite, mpororoite, and hydrokenoelsmoreite. The two former minerals have not been reported to be found in Japan. This is, therefore, the first discovery of anthoinite and mpororoite in Japan. The two minerals form a white powdery mixture with pseudomorphing scheelite. Chemical analysis of the mixture shows that the Al/W ratio is approximate to 1 and that the Fe 2O 3 content is very low, suggesting that the ideal formulae of anthoinite and mpororoite are WAlO 3(OH) 3 and WAlO 3(OH) 3·2H 2O, respectively, even though the original mpororoite had a high content of Fe 2O 3 substituting for Al 2O 3. In addition to these two minerals, another tungsten mineral was also found within the scheelite-pseudomorphs. It occurs as aggregates of regular octahedral crystals up to 50 μm in length. The XRD data are in good agreement with those for hydrokenoelsmoreite, but chemical analysis shows that the major components are WO 3, Al 2O 3, and H 2O with no Fe 2O 3. Up to this time, only Fe-containing hydrokenoelsmoreite, once termed ferritungstite according to the old nomenclature, has been widely reported to be found in Japan. This paper is the first to report the occurrence of such an Fe-free hydrokenoelsmoreite in Japan. It is likely that these three secondary minerals of tungsten at Wazuka were formed in an environment where the supply of H 2O and Al 2O 3 and the leaching of calcium ions from scheelite took place simultaneously. The source of Al is ascribed to the decomposition of muscovite in the quartz veins.


Ohnishi M.,12 43 Takehana Ougi cho | Shimobayashi N.,Kyoto University | Kishi S.,Kamisaibara Junior High School | Tanabe M.,2058 3 Niimi | Kobayashi S.,Okayama University of Science
Journal of Mineralogical and Petrological Sciences | Year: 2013

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, a = 96.99(3), β = 108.97(4), γ = 108.15(4)°, and Z = 1. Electron microprobe analyses gave the empirical formula Ca2.15(Mg0.84 Mn0.05Zn0.02Fe0.01Co0.01Ni0.01)∑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.


Ohnishi M.,12 43 Takehana Ougi cho | Shimobayashi N.,Kyoto University | Nishio-Hamane D.,University of Tokyo | Shinoda K.,Osaka City University | And 2 more authors.
Mineralogical Magazine | Year: 2013

Minohlite, a new copper-zinc sulfate mineral related to schulenbergite, was found in the oxidized zone of the Hirao mine at Minoh (Minoo) City, Osaka Prefecture, Japan. The mineral occurs in cracks in altered shale as rosette aggregates up to 100 mm in diameter, composed of hexagonal platy crystals up to 50 mm in diameter and 10 mm in thickness. The associated minerals are chamosite, muscovite, smithsonite, serpierite, ramsbeckite, 'limonite' and chalcopyrite. Minohlite has hexagonal (or trigonal) symmetry with unit-cell parameters of a = 8.2535(11), c = 8.1352(17) Å, V= 479.93(16) Å3 and Z = 1, and possible space groups P6, P6, P6̄/m, P622, P6mm, P6̄2m and P6/mmm (or P3, P3̄, P321, P3m1, P3̄m1, P312, P31m and P3̄1m). The six strongest reflections in the powder X-ray diffraction pattern [d in Å (I) hkl] are 8.138 (20) 001; 4.128 (24) 110; 2.702 (100) 120; 2.564 (76) 121; 1.560 (43) 140; and 1.532 (24) 141. Electron microprobe analyses gave the following values (wt.%): CuO 37.18, ZnO 21.08, FeO 0.49, SO3 16.78, SiO 2 0.44, and H2O 24.03 (by difference). The empirical formula, calculated on the basis of Cu + Zn + Fe + S + Si = 9 atoms per formula unit, is (Cu4 43Zn2.45Fe0.06)Σ 6 94[(SO4)1 99(SiO4) 0 07]Σ2 06(OH)9 64 · 7.81 H 2O, which leads a simplified formula of (Cu,Zn)7(SO 4)2(OH)10 · 8H2O where Cu> Zn. The mineral is bluish-green and transparent with a pearly to vitreous lustre. The streak is pale green. Cleavage is perfect on {001}. The Mohs hardness number is less than 2. The calculated density is 3.28 g cm- 3. The mineral is named after Minoh City, where it was discovered. © 2013 The Mineralogical Society.


Nishio-Hamane D.,University of Tokyo | Ohnishi M.,12 43 Takehana Ougi cho | Minakawa T.,Ehime University | Yamaura J.-I.,University of Tokyo | And 2 more authors.
Journal of Mineralogical and Petrological Sciences | Year: 2012

The first Cr-dominant amphibole, ehimeite, ideally NaCa 2Mg 4CrSi 6Al 2O 22(OH) 2, has been found in a chromitite deposit in the Akaishi Mine, Higashi-Akaishi Mountain, Ehime Prefecture, Japan. Ehimeite occurs as prismatic crystals of up to 1.5 cm in length and 0.5 cm in width and is found in association with chromite, kämmererite (Cr-rich clinochlore), Cr-poor clinochlore, phlogopite, and uvarovite. It is transparent, emerald green to pale green in color with pale green streaks, and has a vitreous luster. Optically, it is biaxial positive with α = 1.644(2), β = 1.647(2), γ = 1.659(2), and 2V calc. = 53°. It has a Mohs' hardness of 6 and densities of 3.08(3) g/cm 3 (measured using heavy liquids) and 3.121 g/cm 3 (calculated from powder diffraction data and the empirical formula). The empirical formula is (Na 0.88K 0.07) Σ0.95(Ca 1.89Na 0.02Mg 0.09) Σ2.00(Mg 4.03Cr 0.62Al 0.19Fe 3+ 0.07Fe 2+ 0.07Ti 0.03) Σ5.00(Si 6.14Al 1.86) Σ8.00O 22(OH) 2 on the basis of O = 22 and OH = 2, and ehimeite mainly forms a solid solution, NaCa 2Mg 4(Cr, Al) Si 6Al 2O 22(OH) 2, with pargasite. It has a monoclinic unit cell with a = 9.9176(14) Å, b = 18.0009(12) Å, c = 5.2850(7) Å, β = 105.400(7)°, V = 909.6 (17) Å 3, and Z = 2, and it belongs to the space group C2/m, as refined from powder XRD data. The eight strongest lines in the powder XRD pattern [d (Å), I/I 0, hkl] are (3.370, 58, 150), (2.932, 43, 221), (2.697, 81, 151), (2.585, 50, 061), (2.546, 100, 202̄), (2.346, 42, 351), (2.156, 35, 261), and (1.514, 55, 263̄). The crystal structure has been refined to R1 = 0.0488 using single-crystal XRD data. It has been concluded that ehimeite in the Akaishi Mine was formed by the reaction of chromitite and the metamorphic fluid in the retrograde stage of serpentinization during the Sanbagawa metamorphism.


Nishio-Hamane D.,University of Tokyo | Ohnishi M.,12 43 Takehana Ougi cho | Momma K.,National Museum of Nature and Science | Shimobayashi N.,Kyoto University | And 3 more authors.
Mineralogical Magazine | Year: 2015

Imayoshiite, Ca3Al(CO3)[B(OH)4](OH)6·12H2O, occurs in cavities in the altered gabbro xenolith in the sepentinized dunite exposed at Suisho-dani, Ise City, Mie Prefecture, Japan. Imayoshiite is colourless and transparent with a vitreous lustre and its aggregates are white with a silky lustre. Imayoshiite has a white streak. Its Mohs hardness is 2-3. It is brittle, the cleavage is distinct on {100} and the fracture is uneven. The mineral is uniaxial (-) with the indices of refraction ω = 1.497(2) and ε = 1.470(2) in white light. Imayoshiite is hexagonal, P63, a = 11.0264(11), c = 10.6052(16) Å by powder diffraction and a = 11.04592(2), c = 10.61502(19) Å by single-crystal diffraction. The structural refinement converged to R 1 = 2.35%. Imayoshiite is the first member of the ettringite group with both CO3 and B(OH)4 anions. © 2015 Mineralogical Society 2015.

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