Birnessite Mineral Data (original) (raw)

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:

Na0.3Ca0.1K0.1Mn4+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 Aufgeklärte Glück 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/Io): 7.27(1), 1.41(0.7), 2.44(0.7),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

| | 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:

PEBirnessite = 13.58 barns/electron
U=PEBirnessite x relectron= 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)

Search for Birnessite using:

[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Birnessite :

A Bijoux Google Search for Birnessite
Adam's Minerals Google Search for Birnessite
Cape Minerals Google Search for Birnessite
Dakota Matrix Minerals Google Search for Birnessite
Excalibur Mineral Corp. Google Search for Birnessite
Exceptional Minerals Google Search for Birnessite
John Betts Fine Minerals Search for Birnessite
McDougall Minerals Google Search for Birnessite
Mineral News Website Link
Rock and Mineral Shows Google Search for Birnessite
Weinrich Minerals, Inc. Google Search for Birnessite

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 Espa�ol

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: