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(Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
Black; dark brown in ...
Named in 1956 by Lloyd Hugh Parker Jones and Angela Alice Milne for the type locality at Birness, Scotland, UK. Earlier called "manganous manganite" by McMurdie (1944).
Isostructural with:
Generally massive, either earthy or as a resinous to dull fine-grained deposit. Sometime is a replacing material of manganese minerals, including silicates. Occurs in some manganese oxide dendrites. Rarely as dark brown needle crystals. Birnessite Group. See also vernadite. Many manganese oxides are better identified using infra-red spectroscopy than by x-ray diffraction because of issues of crystal size, disorder, etc. (Potter and Rossman, 1979).

Classification of Birnessite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"

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

5 : (AB)2X3

7 : Oxides and Hydroxides
18 : Oxides of Mn URL:
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Type Occurrence of Birnessite

General Appearance of Type Material:
Black coating or cement on pebbles
Year of Discovery:
Geological Setting of Type Material:
Concretion in an unconsolidated glacial sedimentary deposit
Associated Minerals at Type Locality:

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

Sub-Vitreous, Resinous, Waxy, Sub-Metallic, Dull, Earthy
Diaphaneity (Transparency):
Usually fine-grained massive
Black; dark brown in transmitted light
Dark brown to brown
Hardness (Mohs):
3 g/cm3 (Measured)    3.4 g/cm3 (Calculated)
Usually earthy

Crystallography of Birnessite

Crystal System:
Class (H-M):
2/m - Prismatic
Space Group:
Cell Parameters:
a = 5.175Å, b = 2.850Å, c = 7.337Å
β = 103.18°
a:b:c = 1.816 : 1 : 2.574
Unit Cell Volume:
V 105.36 ų (Calculated from Unit Cell)
Rarely in platelets, to 50 µm; commonly extremely finely crystalline, spherulitic, cellular. Rarely as divergent sprays of acicular crystals.
Z also given as 0.5
X-Ray Powder Diffraction Data:
7.08 (100)
3.547 (28)
2.468 (17)
2.333 (43)
2.031 (24)
1.711 (29)
1.426 (17)
Birnessite frequently yeilds only 2-4 x-ray peaks. Data above recorded on a marine nodule from the Caribbean Sea; all reflections are typically very broad. See extensive d-value set ICDD 23-1046 (synthetic) 7.09 (100), 5.60 (10), 3.56 (80), 2.74 (10), 2.58 (10), 2.56 (10), 2.51 (70), 2.47 (10), 2.42 (60), 2.31 (10), 2.26 (10), 2.25 (10), 2.21 (40) 2.15 (40), 2.14 (40), 2.09 (10), 1.97 (10), 1.94 (10), 1.86 (40), 1.82 (40), 1.81 (40), 1.77 (20), 1.75 (10), 1.66 (20), 1.63 (20), 1.55 (10), 1.53 (10), 1.52 (10), 1.47 (60), 1.43 (50), 1.41 (40) 1.37 (20). Data from ICDD 13-105 and 18-802 have been superceded.

Optical Data of Birnessite

Uniaxial (-)
RI values:
nω = 1.730 nε = 1.690
Max Birefringence:
δ = 0.040
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
weak to moderate
Optical Extinction:
Parallel. Refractive indices not far from pyrochroite.
The mineral is pseudo-uniaxial (-); an identification by optical properties is impossible.

Chemical Properties of Birnessite

(Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
All elements listed in formula:
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.-%
Common Impurities:

Relationship of Birnessite to other Species

Structurally related to group(s):
Common Associates:
4.FL.05WoodalliteMg6Cr2(OH)16Cl2 · 4H2O
4.FL.05IowaiteMg6Fe23+(OH)16Cl2 · 4H2O
4.FL.05Jamborite(Ni2+1-x,Cox3+(OH)2-x(SO4)x·nH2O [x ≤ ⅓; n ≤ (1 - x)]
4.FL.05MeixneriteMg6Al2(OH)16(OH)2 · 4H2O
4.FL.05MuskoxiteMg7Fe4O13 · 10H2O
4.FL.10HydrocalumiteCa4Al2(OH)12(Cl,CO3,OH)2 · 4H2O
4.FL.15KuzeliteCa4Al2(OH)12[SO4] · 6H2O
4.FL.20Aurorite(Mn2+,Ag,Ca)Mn34+O7 · 3H2O
4.FL.20Chalcophanite(Zn,Fe,Mn)Mn3O7 · 3H2O
4.FL.20ErnienickeliteNiMn3O7 · 3H2O
4.FL.20Jianshuiite(Mg,Mn)Mn3O7 · 3H2O
4.FL.30Asbolane(Ni,Co)2-xMn4+(O,OH)4 · nH2O
4.FL.35BuseriteNa4Mn14O27 · 21H2O
4.FL.40Ranciéite(Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O
4.FL.40Takanelite(Mn,Ca)Mn4O9 · H2O
4.FL.55CianciulliiteMn(Mg,Mn)2Zn2(OH)10 · 2-4H2O
4.FL.60JenseniteCu3[TeO6] · 2H2O
4.FL.65LeisingiteCu(Mg,Cu,Fe,Zn)2[TeO6] · 6H2O
4.FL.70Akdalaite4Al2O3 · H2O
4.FL.75CafetiteCaTi2O5 · H2O
7.18.12Aurorite(Mn2+,Ag,Ca)Mn34+O7 · 3H2O
7.18.13CianciulliiteMn(Mg,Mn)2Zn2(OH)10 · 2-4H2O

Other Names for Birnessite

Name in Other Languages:
Simplified Chinese:水钠锰矿

Other Information

Not fluorescent in UV
Health Risks:
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

Reference List:
McMurdie, H. F. (1944) Trans. Electrochem. Soc., vol. 86, p. 313. [M.A. 9-227.]
McMurdie, H. F. and Golovato E., 1948. Journ. Res. Nat. Bur. Stand., vol. 41, p. 589.
Feitknecht, W. and Marti, W. (1945) Helv. Chim. Acta, vol. 28, p. 129.
Jones, Lloyd Hugh Parker and Milne, Angela Alice (1956): Birnessite, a new manganese oxide mineral from Aberdeenshire, Scotland. Mineralogical Magazine 31, 283-288.
Glover, E. D. (1977): Characterization of a marine birnessite. American Mineralogist, 62, 278-285.
Potter, Russell M. and Rossman, George R. (1979) The tetravalent manganese oxides: identification, hydration, and structural relationships by infrared spectroscopy, American Mineralogist, v. 64, p. 1199-1218.
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.
American Mineralogist (1990), 75, 477-489 (abstract).
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

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.
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