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Daily Crystal: Alleghanyite

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  • Aussie Talie
    Daily Crystal: Alleghanyite http://www.dyet.com/mineral/displayimage.php?album=2&pos=13 Alleghanyite Basic manganese silicate Location; Hamayokokawa Mine,
    Message 1 of 1 , Feb 21, 2013
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      Daily Crystal: Alleghanyite

      http://www.dyet.com/mineral/displayimage.php?album=2&pos=13



      Alleghanyite
      Basic manganese silicate
      Location; Hamayokokawa Mine, Tatunocho, Nagano Prefecture, Japan

      Album name:davedyet / Minerals






      http://www.cs.cmu.edu/afs/cs/user/adg/www/adg-pssnimages.html

      http://www.cs.cmu.edu/afs/cs/user/adg/www/images/minerals/nsilicates/alleghanyite.jpg





      Alleghanyite
      This thumbnail of pink alleghanyite (a manganese hydroxysilicate) comes from its type locality, Bald Knob, Alleghany County, in North
      Carolina. Alleghanyite's also a member of the humite group and dimorphic with ribbeite.
      Thanks to Adam Larson's (Adam's Minerals) auction on eBay for the specimen and the image!




      http://en.wikipedia.org/wiki/Alleghanyite
      http://en.wikipedia.org/wiki/File:Alleghanyite-21573.jpg


       
      Alleghanyite
      From Wikipedia, the free encyclopedia
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      Alleghanyite

      Alleghanyite crystals up to 2 mm in size in a mixed franklinite/calcite/willemite block of 11×6.5×4 cm size. Location: Sterling Mine, Sussex County, New Jersey, USA.
      General
      Categoryhumite mineral
      Formula
      (repeating unit)Mn5(SiO4)2(OH)2
      Strunz classification02.AA.30
      Dana classification02.02.01.02
      Crystal symmetryMonoclinic – prismatic, H-M symbol (2/m), space group P21/a
      Unit cella = 10.46 Å, b = 4.86 Å, c = 8.3 Å, Z = 2; beta = 109.133°
      Identification
      Formula mass492.87 g
      ColorBrown, bright pink, grayish pink, white
      Crystal habitGranular; anhedral to subhedral crystals in matrix
      CleavageNone
      FractureConchoidal
      TenacityBrittle
      Mohs scale hardness5–6
      LusterVitreous
      DiaphaneityTransparent to translucent
      Specific gravity4 (meas.), 4.11 (calc.)
      Optical propertiesBiaxial (-)
      Refractive indexnα = 1.756
      nβ = 1.78
      nγ = 1.792
      Birefringence0.036
      2V angle72° (meas.), 68° (calc.)
      Other characteristicsNon-fluorescent
      References[1][2]
      Alleghanyite is a moderately rare humite mineral with formula Mn5(SiO4)2(OH)2, belonging to the nesosilicates class. In general its occurrences are related with metamorphic (metamorphosed) manganese deposits. The mineral is named after Alleghany County, North Carolina, USA.[1]
      See also
      * Jerrygibbsite
      * Chondrodite
      * Clinohumite
      * Humite
      References
      1. ^ a b Alleghanyite. Mindat
      2. ^ Alleghanyite. Webmineral 

      * This page was last modified on 10 August 2012 at 16:46.

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