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Stichtite-2H

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About Stichtite-2HHide

Formula:
Mg6(Cr,Al)2(CO3)(OH)16 · 4H2O
Colour:
Intense violet to rose-pink; violet to light rose-pink in transmitted light
Lustre:
Waxy, Pearly
Hardness:
1½ - 2
Specific Gravity:
2.05 - 2.15
Crystal System:
Hexagonal
Name:
For the type locality, Barberton District, Transvaal, South Africa.
A polytype of Stichtite

Originally named barbertonite. Recognised as a polytype of stichtite and accordingly discredited (Mills et al., 2011, 2012).



Classification of Stichtite-2HHide

5.DA.45

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

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

Physical Properties of Stichtite-2HHide

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

Optical Data of Stichtite-2HHide

Type:
Uniaxial (-)
RI values:
nω = 1.557 nε = 1.529
Max Birefringence:
δ = 0.028
Image 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 Stichtite-2HHide

Formula:
Mg6(Cr,Al)2(CO3)(OH)16 · 4H2O

Crystallography of Stichtite-2HHide

Crystal System:
Hexagonal
Class (H-M):
6/mmm (6/m 2/m 2/m) - Dihexagonal Dipyramidal
Space Group:
P63/mmc
Cell Parameters:
a = 6.09689(6) Å, c = 15.6193(8) Å
Ratio:
a:c = 1 : 2.562
Unit Cell V:
502.82 ų (Calculated from Unit Cell)
Morphology:
Platy crystals, flattened on {0001}. Massive, in matted or contorted masses of fibers or plates; also as cross-fiber veinlets.
Comment:
Data of cotype specimen (from Mills et al., 2011); Z = 1/4.

First Recorded Occurrence of Stichtite-2HHide

General Appearance of First Recorded Material:
Platy crystals, fibrous matted masses and cross-fiber veinlets
Place of Conservation of First Recorded Material:
Harvard University, Cambridge, Massachusetts, USA (No. 92549)
Geological Setting of First Recorded Material:
Alteration products of chromite in serpentinite
Associated Minerals at First Recorded Locality:

Synonyms of Stichtite-2HHide

Other Language Names for Stichtite-2HHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
Stichtite2 photos of Stichtite-2H associated with Stichtite on mindat.org.
Serpentine Subgroup1 photo of Stichtite-2H associated with Serpentine Subgroup on mindat.org.
Magnesiochromite1 photo of Stichtite-2H associated with Magnesiochromite on mindat.org.
Aragonite1 photo of Stichtite-2H associated with Aragonite on mindat.org.
Chrysotile1 photo of Stichtite-2H associated with Chrysotile on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

5.DA.AlexkhomyakoviteK6(Ca2Na)(CO3)5Cl·6H2OHex. 6/mmm (6/m 2/m 2/m) : P63/mcm
5.DA.05DypingiteMg5(CO3)4(OH)2 · 5H2OMon.
5.DA.05GiorgiositeMg5(CO3)4(OH)2 · 5-6H2O
5.DA.05HydromagnesiteMg5(CO3)4(OH)2 · 4H2OMon.
5.DA.05WidgiemoolthaliteNi5(CO3)4(OH)2 · 5H2OMon.
5.DA.05UM1986-10-CO:ClHMgMnZn (also called Mineral F, Dunn, 1995)Mg5(Zn,Mn)3(CO3)2(OH,Cl)12 · H2O
5.DA.05UM1987-01-CO:HMgSMg4(CO3)2(OH)4 · 6H2O ?Mon.
5.DA.10ArtiniteMg2(CO3)(OH)2 · 3H2OMon.
5.DA.10IndigiriteMg2Al2(CO3)4(OH)2 · 15H2O
5.DA.10ChlorartiniteMg2(CO3)(OH)Cl · 2H2OTrig. 3m : R3c
5.DA.15OtwayiteNi2(CO3)(OH)2 · H2OOrth.
5.DA.15ZaratiteNi3(CO3)(OH)4 · 4H2O ?Iso.
5.DA.20KambaldaiteNaNi4(CO3)3(OH)3 · 3H2OHex.
5.DA.25CallaghaniteCu2Mg2(CO3)(OH)6 · 2H2OMon.
5.DA.30Claraite(Cu,Zn)15(CO3)4(AsO4)2(SO4)(OH)14·7H2OTric.
5.DA.35HydroscarbroiteAl14(CO3)3(OH)36 · nH2OTric.
5.DA.35ScarbroiteAl5(CO3)(OH)13 · 5H2OHex.
5.DA.40CaresiteFe2+4Al2(OH)12[CO3] · 3H2OTrig.
5.DA.40QuintiniteMg4Al2(OH)12[CO3] · 3H2OHex. 6 2 2 : P63 2 2
5.DA.40CharmariteMn2+4Al2(OH)12[CO3] · 3H2O
5.DA.45BrugnatelliteMg6Fe3+(CO3)(OH)13 · 4H2OHex.
5.DA.45ChlormagaluminiteMg4Al2(OH)12Cl2 · 3H2OHex.
5.DA.45Hydrotalcite-2HMg6Al2(CO3)(OH)16 · 4H2OHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
5.DA.45Pyroaurite-2HMg6Fe3+2(OH)16(CO3) · 4H2OHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
5.DA.45ZaccagnaiteZn4Al2(OH)12[CO3] · 3H2OHex.
5.DA.50ComblainiteNi4Co2(OH)12[CO3] · 3H2OTrig.
5.DA.50DesautelsiteMg6Mn3+2(OH)16[CO3] · 4H2OTrig. 3m (3 2/m)
5.DA.50HydrotalciteMg6Al2(OH)16[CO3] · 4H2OTrig. 3m (3 2/m) : R3m
5.DA.50PyroauriteMg6Fe3+2(OH)16[CO3] · 4H2OTrig. 3m (3 2/m) : R3m
5.DA.50ReevesiteNi6Fe3+2(OH)16(CO3) · 4H2OTrig.
5.DA.50StichtiteMg6Cr3+2(OH)16[CO3] · 4H2OTrig. 3m (3 2/m) : R3m
5.DA.50TakoviteNi6Al2(OH)16[CO3] · 4H2OTrig.
5.DA.50UM1998-10-CO:CoHNiCo6Fe2(CO3)(OH)16 · 4H2O ?
5.DA.55CoalingiteMg10Fe3+2(OH)24[CO3] · 2H2OTrig.

Related Minerals - Dana Grouping (8th Ed.)Hide

16b.6.1.1Hydrotalcite-2HMg6Al2(CO3)(OH)16 · 4H2OHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
16b.6.1.3Pyroaurite-2HMg6Fe3+2(OH)16(CO3) · 4H2OHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
16b.6.1.4ZaccagnaiteZn4Al2(OH)12[CO3] · 3H2OHex.

Other InformationHide

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 Stichtite-2HHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
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.
Mills, S.J., Christy, A.G., Genin, J.-M.R., Kameda, T., Colombo, F. (2012): Nomenclature of the hydrotalcite supergroup: natural layered double hydroxides. Mineralogical Magazine, 76, 1289-1336.

Internet Links for Stichtite-2HHide

Localities for Stichtite-2HHide

ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Australia
 
  • Tasmania
    • West Coast municipality
      • Zeehan district
        • North Dundas
R Bottrill, unpublished data
Czech Republic
 
  • 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 Region
      • Tararua District
        • Maharahara
Railton, G.L¹., Watters, W.A. (1990) Minerals of New Zealand. New Zealand Geological Survey Bulletin 104, 89 pages. (¹published as G.L. Railton but his initials should be G.T. not G.L. - Errata sheet inserted in publication).
South Africa (FRL)
 
  • Mpumalanga Province
    • Ehlanzeni District
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
Mineral and/or Locality  
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