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|System:||Monoclinic||Colour:||Black; dark brown in ...|
|Name:||Named in 1956 by L. H. P. Jones and Angela Alice Milne for the type locality at Birness, Scotland, UK.|
Classification of Birnessite
|IMA status:||Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"|
|Strunz 8th edition ID:||4/F.11-30|
|Nickel-Strunz 10th (pending) edition ID:||4.FL.45|
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
L : Hydroxides with H2O +- (OH); sheets of edge-sharing octahedra
|Dana 8th edition ID:||126.96.36.199|
7 : MULTIPLE OXIDES
5 : (AB)2X3
|Hey's CIM Ref.:||7.18.11|
7 : Oxides and Hydroxides
18 : Oxides of Mn
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Type Occurrence of Birnessite
|Type Locality:||Birness, Ellon, Buchan Grampian (Aberdeenshire), Scotland, UK|
Occurrences of Birnessite
|Geological Setting:||A major manganese-bearing mineral of many soils; a common alteration product of manganese-rich mineral deposits; a component of bacterially-precipitated manganese oxides; an important constituent of "desert varnish" and marine manganese nodules.|
Physical Properties of Birnessite
|Colour:||Black; dark brown in transmitted light|
|Density (measured):||3 g/cm3|
|Density (calculated):||3.4 g/cm3|
Crystallography of Birnessite
|Class (H-M):||2/m - Prismatic|
|Cell Parameters:||a = 5.175Å, b = 2.85Å, c = 7.337Å|
β = 103.18°
|Ratio:||a:b:c = 1.816 : 1 : 2.574|
|Unit Cell Volume:||V 105.36 Å³ (Calculated from Unit Cell)|
|Morphology:||Rarely in platelets, to 50 µm; commonly extremely finely crystalline, spherulitic, cellular.|
|X-Ray Powder Diffraction:|
|Comments:||Recorded on a marine nodule from the Caribbean Sea; all reflections are typically very broad.|
Optical Data of Birnessite
|RI values:||nω = 1.730 nε = 1.690|
|Maximum Birefringence:||δ = 0.040|
Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
|Dispersion:||weak to moderate|
|Comments:||The mineral is pseudo-uniaxial (-); an identification by optical properties is impossible.|
Chemical Properties of Birnessite
|Simplified for copy/paste:||(Na,Ca)0.5(Mn4+,Mn3+)2O4·1.5H2O|
|Essential elements:||H, Mn, Na, O|
|All elements listed in formula:||Ca, H, Mn, Na, O|
|Analytical Data:||Electron microprobe analysis of a marine nodule from the Caribbean Sea; total Mn calculated as MnO2, H2O content calculated from the mass balance|
SiO2 (0.9) MnO2 (75.8) FeO (0.55) CoO (0.14) NiO (0.80) CuO (0.33) MgO (6.2) CaO (0.39) Na2O (1.9) K2O (1.8) Cl (0.1) H2O (10.89) S (0.2) sum 100.00 wt.-%
Relationship of Birnessite to other Species
|Structurally related to group(s):|
|Related Minerals - Nickel-Strunz Grouping):|
|Related Minerals - Hey's Index Grouping:|
Other Names for Birnessite
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Birnessite
Jones, L. H. P. and Milne, A. A. (1956): Birnessite, a new manganese oxide mineral from Aberdeenshire, Scotland. Mineralogical Magazine 31, 283-288. - American Mineralogist (1990), 75, 477-489 (abstract).
Glover, E. D. (1977): Characterization of a marine birnessite. American Mineralogist 62, 278-285.
Chukhrov, F. V., Gorshkov, A. I., Rudnitskaya, E. S., Beresovskaya, V. V., and Sivtsov, A. V. (1980): Manganese minerals in clay: a review. Clays and Clay Minerals 28, 346-453.
Golden, D. C., Dixon, J. B. and Chen, C. C. (1986): Ion exchange, thermal transformations, and oxidizing properties of birnessite. Clays and Clay Minerals 34, 511-520.
Golden, D. C., Chen, C. C., and Dixon, J. B. (1987): Transformation of birnessite to buserite, todorokite, and manganite under mild hydrothermal treatment. Clays and Clay Minerals 35, 271-280.
Post, J. E., and Veblen, D. R. (1990): Crystal structure determinations of synthetic sodium, magnesium and potassium birnessite using TEM and the Rietveld method. American Mineralogist 75, 477-489.
Anthony, J. W. et al. (1997): Handbook of Mineralogy, Vol. 3, 58.
Lanson, B., Drits, V. A., E. Silvester, E., and Manceau, A. (2000): Structure of H-exchanged hexagonal birnessite and its mechanism of formation from Na-rich monoclinic buserite at low pH. American Mineralogist 85, 826-838.
Lanson, B., Drits, V. A., Gaillot, A., Silvester, E., Plançon, A., and Manceau, A. (2002): Structure of the heavy-metal sorbed birnessite: Part I. Results from X-ray diffraction. American Mineralogist 87, 1631-1645.
Johnson, E. A., and Post, J. E. (2006): Water in the interlayer region of birnessite: Importance in cation exchange and structural stability. American Mineralogist 91, 609-618.
Internet Links for Birnessite
Localities for Birnessite
The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
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