Birnessite Mineral Data

General Birnessite Information

Chemical Formula:

(Na,Ca,K)x(Mn++++,Mn+++)2O4•1.5(H2O)

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

Empirical Formula:

Na_0.3Ca_0.1K_0.1Mn⁴⁺Mn³⁺O₄•1.5(H₂O)

Environment:

Found as grains cementing gravel in a road cut 30 km N of Aberdeen. Major component of desert varnish. Deep sea Mn nodules.

IMA Status:

Valid Species (Pre-IMA) 1956

Locality:

Birness, Aberdeenshire, Scotland. Link to MinDat.org Location Data.

Name Origin:

Named after the locality.

Name Pronunciation:

Birnessite + Pronunciation

Synonym:

ICSD 68916

PDF 23-1046

Birnessite Image

Images:

Birnessite

Comments: Gray birnessite. Very small crystals on massive material.
Location: Das AufgeklÃ¤rte GlÃ¼ck Mine, Hasserode, Wernigerode, Harz Mts, Saxony-Anhalt, Germany. Scale: Picture size 7 mm.
© Thomas Witzke / Abraxas-Verlag

Images:

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

Axial Ratios:

a:b:c =1.8154:1:2.574

Cell Dimensions:

a = 5.174, b = 2.85, c = 7.336, Z = 1; beta = 103.18° V = 105.33 Den(Calc)= 3.40

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 7.27(1), 1.41(0.7), 2.44(0.7),

Crystal Structure:

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Post J E , Veblen D R , American Mineralogist , 75 (1990) p.477-489, Crystal structure determinations of synthetic sodium, magnesium and potassium, birnessite using TEM and the Rietveld method, sample is Na-birn

View Additional jPOWD Structure files for Birnessite
[1] [2]

Physical Properties of Birnessite

Color:

Dark brown, Black.

Density:

Diaphaneity:

Subopaque

Habit:

Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

1.5 - Between Talc and Gypsum

Luster:

Sub Metallic

Optical Properties of Birnessite

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

Optical Data:

Biaxial (?), a=1.69, g=1.73, bire=0.0400

Calculated Properties of Birnessite

Electron Density:

Bulk Density (Electron Density)=2.90 gm/cc
note: Specific Gravity of Birnessite =3.00 gm/cc.

Fermion Index:

Fermion Index = 0.0002251701
Boson Index = 0.9997748299

Photoelectric:

PE_Birnessite= 13.58 barns/electron
U=PE_Birnessite x r_electron= 39.35 barns/cc.

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

Dana Class:

07.05.03.01 (07)Multiple Oxides

(07.05)where A B X2

(07.05.03)Dana Group

07.05.03.01 Birnessite (Na,Ca,K)x(Mn,Mn)2O4•1.5(H2O) C 2/m 2/m

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

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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
19 - WWW-MINCRYST

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Ask about Birnessite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Birnessite Specimen Label here :

Birnessite

(Na,Ca,K)x(Mn++++,Mn+++)2O4•1.5(H2O)
Dana No: 07.05.03.01 Strunz No: 04.FL.45
Locality:

Notes: