Tanohataite, limn2si3o8(OH): A new mineral from the Tanohata mine, Iwate Prefecture, Japan

Toshiro Nagase, Hidemichi Hori, Mizuya Kitamine, Mariko Nagashima, Ahmadjan Abduriyim, Takahiro Kuribayashi

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8 Citations (Scopus)


Tanohataite, LiMn2Si3O8(OH), the Li analogue of serandite, has been found in a metamorphosed manganese ore deposit of the Tanohata mine, Iwate Prefecture, Japan. The mineral has the triclinic space group P1 with a = 7.612(7), b = 7.038(4), c = 6.700(4) Å, α = 90.23(6)°, β = 94.70(7)°, γ = 105.26 (8)°, V =345.0(3) Å3, and Z = 2. The seven strongest lines in the X-ray powder diffraction pattern are [d(Å), (I), (hkl)]: 6.64(35)(001), 3.67(26) (200), 3.13(89)(1̄02), 3.11(69)(21̄1), 2.95(100)(102), 2.81(33)(120), and 2.18(40)(103). Electron microprobe analysis and laser ablation microprobe-inductively coupled plasma-mass spectrometry gave an SiO2 content of 51.97; MnO, 37.99; MgO, 1.06; CaO, 0.41; Na2O, 1.97; Li2O, 3.34; total, 96.74 wt%, corresponding to an empirical formula of (Li0.78Na0.221.00(Mn1.86 Ca0.03Mg0.091.98Si3.01 O8(OH) on the basis of O = 9. Tanohataite is transparent and pinkish white with a vitreous and silky luster. The streak is white. The cleavage is perfect on {001} and {100}. On the Mohs' scale, the hardness is 5-51/2. The calculated density is 3.33 g/cm3. Optically, tanohataite is biaxial positive with 2Vcalc = 82(2)°, α = 1.593(3), β = 1.618(3), and γ = 1.653(3). Tanohataite occurs as an aggregation of fibrous crystals in veinlets composed mainly of quartz, aegirine, Mn-arfvedsonite, nambulite, natronambulite, and barite.

Original languageEnglish
Pages (from-to)149-154
Number of pages6
JournalJournal of Mineralogical and Petrological Sciences
Issue number3
Publication statusPublished - 2012


  • Chemical composition
  • TEM
  • Tanohata mine
  • Tanohataite
  • XRD


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