Numanoite, Ca4CuB4O6(OH)6 (CO3)2, a new mineral species, the Cu analogue of borcarite from the Fuka mine, Okayama Prefecture, Japan

Masayuki Ohnishi, Isao Kusachi, Shoichi Kobayashi, Junji Yamakawa, Mitsuo Tanabe, Shigetomo Kishi, Takashi Yasuda

Research output: Contribution to journalArticle

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Abstract

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 horcarite 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 C2/m, a 17.794(2), b 8.381(1), c 4.4494(7) Å, β 102.42(2)° and Z = 2. The strongest seven lines in the X-ray powder-diffraction pattern [d in Å(I)(hkl)] are 7.57(100)(110), 2.671(84)(4̄21), 2.727(68)(221), 1.887(52)(041,440), 2.272(48)(3̄31), 2.899(44)(600) and 1.698(34)(640). Electron-microprobe and thermogravimetric analyses gave B2O3 24.09, CaO 38.11, CuO 10.32, MgO 1.02, ZnO 0.51, CO2 15.80, H2O 9.75, sum 99.60 wt.%. The empirical formula, calculated on the basis of O = 18, is Ca3.898(Cu0.744Mg0.145 Zn0.036)∑0.925B3.969 O5.615(OH)6.208(CO3)2.059, ideally Ca4Cu B4O6(OH)6 (CO3)2. The mineral is optically biaxial negative, α 1.618(2), β 1.658(2), γ 1.672(2), and 2Vcalc = 60°. The mineral has perfect cleavages in two directions. The density is 2.96(2) g/cm3 (meas.) and 2.93 g/cm3 (calc.). The Vickers microhardness is 376 (290-464) kg/mm2 (25 g load), and the Mohs hardness number is 41/2. 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.

Original languageEnglish
Pages (from-to)307-315
Number of pages9
JournalCanadian Mineralogist
Volume45
Issue number2
DOIs
Publication statusPublished - Apr 2007

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new mineral
Minerals
mineral
Calcium Carbonate
crystal
Bearings (structural)
differential thermal analysis
silicate mineral
Crystals
electron probe analysis
cleavage
hardness
magnesium
calcite
Microhardness
X ray powder diffraction
Differential thermal analysis
Diffraction patterns
X-ray diffraction
limestone

Keywords

  • Borcarite
  • Fuka mine
  • Gehlenite-spurrite skarn
  • Hydrothermal solution
  • Japan
  • Numanoite

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

Numanoite, Ca4CuB4O6(OH)6 (CO3)2, a new mineral species, the Cu analogue of borcarite from the Fuka mine, Okayama Prefecture, Japan. / Ohnishi, Masayuki; Kusachi, Isao; Kobayashi, Shoichi; Yamakawa, Junji; Tanabe, Mitsuo; Kishi, Shigetomo; Yasuda, Takashi.

In: Canadian Mineralogist, Vol. 45, No. 2, 04.2007, p. 307-315.

Research output: Contribution to journalArticle

Ohnishi, Masayuki ; Kusachi, Isao ; Kobayashi, Shoichi ; Yamakawa, Junji ; Tanabe, Mitsuo ; Kishi, Shigetomo ; Yasuda, Takashi. / Numanoite, Ca4CuB4O6(OH)6 (CO3)2, a new mineral species, the Cu analogue of borcarite from the Fuka mine, Okayama Prefecture, Japan. In: Canadian Mineralogist. 2007 ; Vol. 45, No. 2. pp. 307-315.
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abstract = "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 horcarite 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 C2/m, a 17.794(2), b 8.381(1), c 4.4494(7) {\AA}, β 102.42(2)° and Z = 2. The strongest seven lines in the X-ray powder-diffraction pattern [d in {\AA}(I)(hkl)] are 7.57(100)(110), 2.671(84)(4̄21), 2.727(68)(221), 1.887(52)(041,440), 2.272(48)(3̄31), 2.899(44)(600) and 1.698(34)(640). Electron-microprobe and thermogravimetric analyses gave B2O3 24.09, CaO 38.11, CuO 10.32, MgO 1.02, ZnO 0.51, CO2 15.80, H2O 9.75, sum 99.60 wt.{\%}. The empirical formula, calculated on the basis of O = 18, is Ca3.898(Cu0.744Mg0.145 Zn0.036)∑0.925B3.969 O5.615(OH)6.208(CO3)2.059, ideally Ca4Cu B4O6(OH)6 (CO3)2. The mineral is optically biaxial negative, α 1.618(2), β 1.658(2), γ 1.672(2), and 2Vcalc = 60°. The mineral has perfect cleavages in two directions. The density is 2.96(2) g/cm3 (meas.) and 2.93 g/cm3 (calc.). The Vickers microhardness is 376 (290-464) kg/mm2 (25 g load), and the Mohs hardness number is 41/2. 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.",
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author = "Masayuki Ohnishi and Isao Kusachi and Shoichi Kobayashi and Junji Yamakawa and Mitsuo Tanabe and Shigetomo Kishi and Takashi Yasuda",
year = "2007",
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language = "English",
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journal = "Canadian Mineralogist",
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T1 - Numanoite, Ca4CuB4O6(OH)6 (CO3)2, a new mineral species, the Cu analogue of borcarite from the Fuka mine, Okayama Prefecture, Japan

AU - Ohnishi, Masayuki

AU - Kusachi, Isao

AU - Kobayashi, Shoichi

AU - Yamakawa, Junji

AU - Tanabe, Mitsuo

AU - Kishi, Shigetomo

AU - Yasuda, Takashi

PY - 2007/4

Y1 - 2007/4

N2 - 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 horcarite 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 C2/m, a 17.794(2), b 8.381(1), c 4.4494(7) Å, β 102.42(2)° and Z = 2. The strongest seven lines in the X-ray powder-diffraction pattern [d in Å(I)(hkl)] are 7.57(100)(110), 2.671(84)(4̄21), 2.727(68)(221), 1.887(52)(041,440), 2.272(48)(3̄31), 2.899(44)(600) and 1.698(34)(640). Electron-microprobe and thermogravimetric analyses gave B2O3 24.09, CaO 38.11, CuO 10.32, MgO 1.02, ZnO 0.51, CO2 15.80, H2O 9.75, sum 99.60 wt.%. The empirical formula, calculated on the basis of O = 18, is Ca3.898(Cu0.744Mg0.145 Zn0.036)∑0.925B3.969 O5.615(OH)6.208(CO3)2.059, ideally Ca4Cu B4O6(OH)6 (CO3)2. The mineral is optically biaxial negative, α 1.618(2), β 1.658(2), γ 1.672(2), and 2Vcalc = 60°. The mineral has perfect cleavages in two directions. The density is 2.96(2) g/cm3 (meas.) and 2.93 g/cm3 (calc.). The Vickers microhardness is 376 (290-464) kg/mm2 (25 g load), and the Mohs hardness number is 41/2. 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.

AB - 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 horcarite 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 C2/m, a 17.794(2), b 8.381(1), c 4.4494(7) Å, β 102.42(2)° and Z = 2. The strongest seven lines in the X-ray powder-diffraction pattern [d in Å(I)(hkl)] are 7.57(100)(110), 2.671(84)(4̄21), 2.727(68)(221), 1.887(52)(041,440), 2.272(48)(3̄31), 2.899(44)(600) and 1.698(34)(640). Electron-microprobe and thermogravimetric analyses gave B2O3 24.09, CaO 38.11, CuO 10.32, MgO 1.02, ZnO 0.51, CO2 15.80, H2O 9.75, sum 99.60 wt.%. The empirical formula, calculated on the basis of O = 18, is Ca3.898(Cu0.744Mg0.145 Zn0.036)∑0.925B3.969 O5.615(OH)6.208(CO3)2.059, ideally Ca4Cu B4O6(OH)6 (CO3)2. The mineral is optically biaxial negative, α 1.618(2), β 1.658(2), γ 1.672(2), and 2Vcalc = 60°. The mineral has perfect cleavages in two directions. The density is 2.96(2) g/cm3 (meas.) and 2.93 g/cm3 (calc.). The Vickers microhardness is 376 (290-464) kg/mm2 (25 g load), and the Mohs hardness number is 41/2. 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.

KW - Borcarite

KW - Fuka mine

KW - Gehlenite-spurrite skarn

KW - Hydrothermal solution

KW - Japan

KW - Numanoite

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