Mineralogy Database

Birnessite Mineral Data

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General Birnessite Information

Help on Chemical  Formula: Chemical Formula: (Na,Ca,K)x(Mn++++,Mn+++)2O4•1.5(H2O)
Help on Composition: Composition: Molecular Weight = 215.71 gm
   Potassium   1.81 %  K     2.18 % K2O
   Sodium      3.20 %  Na    4.31 % Na2O
   Calcium     1.86 %  Ca    2.60 % CaO
   Manganese  50.94 %  Mn   36.59 % Mn2O3 / 40.30 % MnO2
   Hydrogen    1.40 %  H    12.53 % H2O
   Oxygen     40.79 %  O
             ______        ______ 
             100.00 %       98.52 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Na0.3Ca0.1K0.1Mn4+Mn3+O4•1.5(H2O)
Help on Environment: Environment: Found as grains cementing gravel in a road cut 30 km N of Aberdeen. Major component of desert varnish. Deep sea Mn nodules.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1956
Help on Locality: Locality: Birness, Aberdeenshire, Scotland. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named after the locality.
Help on Name Pronunciation: Name Pronunciation: Birnessite + Pronunciation Say BIRNESSITE
Help on Synonym: Synonym: ICSD 68916
  PDF 23-1046

Birnessite Image

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Comments: Gray birnessite. Very small crystals on massive material.
Location: Das Aufgeklärte Glück Mine, Hasserode, Wernigerode, Harz Mts, Saxony-Anhalt, Germany. Scale: Picture size 7 mm.
© Thomas Witzke / Abraxas-Verlag

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  Birnessite   Buserite

Comments: Round, "rabbit pellets" of buserite which dehydrates to birnessite when dry. Image photographed through water which is needed to preserve this species.
Location: Aomori Springs, Oppu, Japan. Scale: Sphere size 7 mm.
© Dave Barthelmy

Birnessite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =1.8154:1:2.574
Help on Cell Dimensions: Cell Dimensions: a = 5.174, b = 2.85, c = 7.336, Z = 1; beta = 103.18° V = 105.33 Den(Calc)= 3.40
Help on Crystal System: Crystal System: Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/m
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 7.27(1), 1.41(0.7), 2.44(0.7),

Physical Properties of Birnessite

Help on Color: Color: Dark brown, Black.
Help on Density: Density: 3
Help on Diaphaneity: Diaphaneity: Subopaque
Help on Habit: Habit: Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).
Help on Habit: Habit: Massive - Uniformly indistinguishable crystals forming large masses.
Help on Hardness: Hardness: 1.5 - Between Talc and Gypsum
Help on Luster: Luster: Sub Metallic

Optical Properties of Birnessite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.282 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.366 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2088,KPDmeas= 0.2367,KC= 0.3294
Ncalc = 1.99 - 2.12
Help on Optical Data: Optical Data: Biaxial (?), a=1.69, g=1.73, bire=0.0400

Calculated Properties of Birnessite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.90 gm/cc
note: Specific Gravity of Birnessite =3.00 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0002251701
Boson Index = 0.9997748299
Help on Photoelectric: Photoelectric: PEBirnessite = 13.58 barns/electron
U=PEBirnessite x relectron= 39.35 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 25.26 (Gamma Ray American Petroleum Institute Units)
Concentration of Birnessite per GRapi unit = 3.96 (%)

Estimated Radioactivity from Birnessite - barely detectable


Birnessite Classification

Help on  Dana Class: Dana Class: (07)Multiple Oxides
  (07.05)where A B X2
  (07.05.03)Dana Group Birnessite (Na,Ca,K)x(Mn,Mn)2O4•1.5(H2O) C 2/m 2/m
Help on  Strunz Class: Strunz Class: 04.FL.45 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate
  04.F - Hydroxides (without V or U)
  04.FL -Hydroxides with H2O � (OH); sheets of edge-sharing octahedra
04.FL.45 Birnessite (Na,Ca,K)x(Mn,Mn)2O4•1.5(H2O) C 2/m 2/m

Other Birnessite Information

Help on References: References: NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
Help on See Also: See Also: Links to other databases for Birnessite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Athena
5 - EUROmin Project
6 - Ecole des Mines de Paris
7 - Franklin Minerals(Dunn)
8 - GeoScienceWorld
9 - Google Images
10 - Google Scholar
11 - Handbook of Mineralogy (MinSocAm)
12 - Handbook of Mineralogy (UofA)
13 - HyperPhysics
14 - MinDAT
15 - Mineralienatlas (Deutsch)
16 - Online Mineral Museum
17 - QUT Mineral Atlas
18 - Ruff.Info

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Dana No: Strunz No: 04.FL.45





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