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Barbertonite

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Big Photo

Roadcut stichtite occurrence, Kaapsche Hoop (Kaapsehoop), Barberton District, Mpumalanga Province, South Africa
© JEFS

Show Barbertonite Photos (3)



Formula:
Mg
 
6
(Cr,Al)
 
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
System:HexagonalColour:Intense violet to ...
Hardness:1½ - 2
Member of:Manasseite Group
Name:For the type locality, Barberton District, Transvaal, South Africa.


Manasseite Group.

Study of the type material by Mills et al. (2011) shows that barbertonite is the -2H polytype of stichtite. Discreditation awaits the IMA hydrotalcite subcommiteee.

Classification of Barbertonite

IMA status:Questionable/Doubtful
Strunz 8th edition ID:5/E.02-30
Nickel-Strunz 10th (pending) edition ID:5.DA.45

5 : CARBONATES (NITRATES)
D : Carbonates with additional anions, with H2O
A : With medium-sized cations
Dana 8th edition ID:16b.6.1.2

16b : HYDRATED CARBONATES CONTAINING HYDROXYL OR HALOGEN
6 : AmBn(XO3)pZqxH2O & with (m+n):p = 8:1
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Type Occurrence of Barbertonite

Type Locality:Barberton District, Mpumalanga Province, South Africa
General Appearance of Type Material:Platy crystals, fibrous matted masses and cross-fiber veinlets
Place of Conservation of Type Material:Harvard University, Cambridge, Massachusetts, USA (No. 92549)
Year of Discovery:1940
Geological Setting of type material:Alteration products of chromite in serpentinite
Associated Minerals at type locality:
StichtiteChromiteAntigorite

Physical Properties of Barbertonite

Lustre:Waxy, Pearly
Diaphaneity (Transparency):Transparent
Colour:Intense violet to rose-pink; violet to light rose-pink in transmitted light
Streak:Very pale violet to white
Hardness (Mohs):1½ - 2
Tenacity:Elastic
Cleavage:Perfect
on {0001}
Density (measured):2.05 - 2.15 g/cm3
Density (calculated):2.11 g/cm3

Crystallography of Barbertonite

Crystal System:Hexagonal
Cell Parameters:a = 6.17Å, c = 15.52Å
Ratio:a:c = 1 : 2.515
Unit Cell Volume:V 511.67 ų (Calculated from Unit Cell)
Z:1
Morphology:Platy crystals, flattened on {0001}. Massive, in matted or contorted masses of fibers or plates; alos as cross-fiber veinlets.

Optical Data of Barbertonite

Type:Uniaxial (-)
RI values: nω = 1.557 nε = 1.529
Maximum Birefringence:δ = 0.028

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Pleochroism:Weak
Comments:O = dark rose-pink to violet
E = light rose-pink to violet

Chemical Properties of Barbertonite

Formula:
Mg
 
6
(Cr,Al)
 
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
Essential elements:C, Cr, H, Mg, O
All elements listed in formula:Al, C, Cr, H, Mg, O
Analytical Data:Intimately intermixed with stichtite; analyses of pure material are therefore lacking. The species is supported by X-ray diffraction patterns showing group membership.
Relationship of Barbertonite to other Species
Member of:Manasseite Group
Other Members of Group:

- + 
Fougèrite
(Fe
2+
 
,Mg)
 
6
Fe
3+
2
(OH)
 
18
 · 4H
 
2
O
Manasseite
Mg
 
6
Al
 
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
Sjögrenite
Mg
 
6
Fe
3+
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
Related Minerals - Nickel-Strunz Grouping):

- + 
5.DA.05Dypingite
Mg
 
5
(CO
 
3
)
 
4
(OH)
 
2
 · 5H
 
2
O
5.DA.05Giorgiosite
Mg
 
5
(CO
 
3
)
 
4
(OH)
 
2
 · 5-6H
 
2
O
5.DA.05Hydromagnesite
Mg
 
5
(CO
 
3
)
 
4
(OH)
 
2
 · 4H
 
2
O
5.DA.05Widgiemoolthalite
Ni
 
5
(CO
 
3
)
 
4
(OH)
 
2
 · 5H
 
2
O
5.DA.05UM1986-10-CO:ClHMgMnZn
Mg
 
5
(Zn,Mn)
 
3
(CO
 
3
)
 
2
(OH,Cl)
 
12
 · H
 
2
O
5.DA.05UM1987-01-CO:HMgS
Mg
 
4
(CO
 
3
)
 
2
(OH)
 
2
 · 6H
 
2
O ?
5.DA.10Artinite
Mg
 
2
(CO
 
3
)(OH)
 
2
 · 3H
 
2
O
5.DA.10Indigirite
Mg
 
2
Al
 
2
(CO
 
3
)
 
4
(OH)
 
2
 · 15H
 
2
O
5.DA.10Chlorartinite
Mg
 
2
(CO
 
3
)(OH)Cl · 2H
 
2
O
5.DA.15Otwayite
Ni
 
2
(CO
 
3
)(OH)
 
2
 · H
 
2
O
5.DA.15Zaratite
Ni
 
3
(CO
 
3
)(OH)
 
4
 · 4H
 
2
O
5.DA.20Kambaldaite
NaNi
 
4
(CO
 
3
)
 
3
(OH)
 
3
 · 3H
 
2
O
5.DA.25Callaghanite
Cu
 
2
Mg
 
2
(CO
 
3
)(OH)
 
6
 · 2H
 
2
O
5.DA.30Claraite
(Cu,Zn)
 
3
(CO
 
3
)(OH)
 
4
 · 4H
 
2
O
5.DA.35Hydroscarbroite
Al
 
14
(CO
 
3
)
 
3
(OH)
 
36
 · nH
 
2
O
5.DA.35Scarbroite
Al
 
5
(CO
 
3
)(OH)
 
13
 · 5H
 
2
O
5.DA.40Caresite
Fe
2+
4
Al
 
2
(CO
 
3
)(OH)
 
12
 · 3H
 
2
O
5.DA.40Quintinite
Mg
 
4
Al
 
2
(CO
 
3
)(OH)
 
12
 · H
 
2
O
5.DA.40Charmarite
Mn
2+
4
Al
 
2
(CO
 
3
)(OH)
 
12
 · 3H
 
2
O
5.DA.45Brugnatellite
Mg
 
6
Fe
3+
 
(CO
 
3
)(OH)
 
13
 · 4H
 
2
O
5.DA.45Chlormagaluminite
(Mg,Fe
2+
 
)
 
4
Al
 
2
(Cl
 
2
,CO
 
3
)(OH)
 
12
 · 2H
 
2
O
5.DA.45Manasseite
Mg
 
6
Al
 
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
5.DA.45Sjögrenite
Mg
 
6
Fe
3+
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
5.DA.45Zaccagnaite
Zn
 
4
Al
 
2
(CO
 
3
)(OH)
 
12
 · 3H
 
2
O
5.DA.50Comblainite
Ni
 
6
Co
 
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
5.DA.50Desautelsite
Mg
 
6
Mn
3+
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
5.DA.50Hydrotalcite
Mg
 
6
Al
 
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
5.DA.50Pyroaurite
Mg
 
6
Fe
3+
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
5.DA.50Reevesite
Ni
 
6
Fe
3+
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
5.DA.50Stichtite
Mg
 
6
Cr
 
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
5.DA.50Takovite
Ni
 
6
Al
 
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O
5.DA.50UM1998-10-CO:CoHNi
Co
 
6
Fe
 
2
(CO
 
3
)(OH)
 
16
 · 4H
 
2
O ?
5.DA.55Coalingite
Mg
 
10
Fe
3+
2
(CO
 
3
)(OH)
 
24
 · 2H
 
2
O
Other Names for Barbertonite
Other Languages:
Bosnian (Cyrillic Script):Barbertonite
German:Barbertonit
Spanish:Barbertonita
Other Information
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 Barbertonite
Reference List:

- + 
Read and Dixon (1933), Mineralogical Magazine: 23: 309.



Mineralogical Society of America Annual Meeting, Program Abstracts, 1940, 6.



Frondel, C. (1941): Constitution and polymorphism of the pyroaurite and sjögrenite groups. American Mineralogist 26, 295-315.



Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 659.



Taylor, H. W. F. (1973): Crystal structures of some double hydroxide minerals. Mineralogical Magazine 39, 377-389.



Anthony, J. W. et al. (1997): Handbook of Mineralogy, Vol. 3, 39.



Mills, S. J., Whitfield, P. S., Wilson, S. A., Woodhouse, J. A., Dipple, G. M., Raudsepp, M. & Francis, C. A. (2011) The crystal structure of stitchtite, re-examination of barbertonite and the nature of polytypism in MgCr hydrotalcites. American Mineralogist, 96(1), 179–187.
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    • Localities for Barbertonite
    






    


    

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the  symbol to view information about a locality. 
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can be used to jump to that position on the map.

    

    

    
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    (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.

    Australia
     
    

    • Tasmania
    

      • Zeehan district
    

        • North Dundas
    
    		R Bottrill, unpublished data
    Czech Republic
     
    

    • Moravia (Mähren; Maehren)
    

      • South Moravia Region
    

        • Letovice (Lettowitz)
    
    		Ulrych, J.: Stichtit z hadcového tělesa od Slatinky u Letovic. Časopis pro mineralogii a geologii, 1966, roč. 11, č. 3, s. 311-315.
    New Zealand
     
    

    • North Island
    

      • Manawatu-Wanganui
    

        • Tararua
    

          • Maharahara
    
    		Railton, G.L. & Watters, W.A. (1990):  Minerals of New Zealand
    South Africa
     
    

    • Mpumalanga Province
    
    		Am Min 26 (1941), 295
    



        • Kaapsche Hoop (Kaapsehoop)
    
    		Rocks & Min.: 21:275.
    UK
     
    

    • Scotland
    

      • Shetland Islands
    

        • Mainland
    

          • Cunningsburgh
    
    		Anthony, J. W. et al. (1997): Handbook of Mineralogy, Vol. 3, 39
    

    


    

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