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About SöhngeiteHide

A. P. Gerhard Söhnge
Brown, white,pale yellow, pale brown, pale greenish yellow
4 - 4½
Specific Gravity:
Crystal System:
Named in 1965 by H. Strunz in honor of Adolf Paul Gerhard Söhnge (10 November 1913, Saron, Western Cape, South Africa - 14 July 2006), chief geologist, Tsumeb corporation, Tsumeb, Namibia, who discovered the mineral. He was also a professor at the Stellenbosch University (1968-1978).
Söhngeite Group. The Ga analogue of bernalite and dzhalindite. One of a very few approved minerals with species-defining gallium; compare gallite, tsumgallite, gallobeudantite and galloplumbogummite.

Structurally a hydroxide perovskite. The structure has 5 independent OH groups and is based on Ga(OH)6 octahedra.

Classification of SöhngeiteHide

Approval Year:

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
C : Hydroxides with OH, without H2O; corner-sharing octahedra

3 : X(OH)3

7 : Oxides and Hydroxides
7 : Oxides of Group III metals other than Al

Physical Properties of SöhngeiteHide

Brown, white,pale yellow, pale brown, pale greenish yellow
4 - 4½ on Mohs scale
3.84 g/cm3 (Measured)    3.847 g/cm3 (Calculated)

Optical Data of SöhngeiteHide

RI values:
n = 1.736
Isotropic minerals have no birefringence
Surface Relief:

Chemical Properties of SöhngeiteHide


Crystallography of SöhngeiteHide

Crystal System:
Cell Parameters:
a = 7.4546 Å, c = 7.3915 Å
a:c = 1 : 0.992
Unit Cell V:
410.75 ų (Calculated from Unit Cell)
trillings of composite flattened, curved crystals; interpenetrant at right angles according to an unknown
P42/nmc or P42/n (both refinements give good results); previously thought to be orthorhombic (pseudocubic), Pmn21, but this was shown to be unlikely for a hydroxide perovskite

X-Ray Powder DiffractionHide

Powder Diffraction Data:
3.74 (100)
1.669 (70)
2.63 (60)
1.525 (60)
1.867 (40)
2.15 (35)
2.36 (30)

Type Occurrence of SöhngeiteHide

General Appearance of Type Material:
crystalline, twinned groups and aggregates, up to 1 cm; single crystals are very rare
Geological Setting of Type Material:
the oxidation product of gallite-bearing germanite ore, within an oxidation zone of a hydrothermal polymetallic deposit.
Associated Minerals at Type Locality:

Synonyms of SöhngeiteHide

Other Language Names for SöhngeiteHide


Relationship of Söhngeite to other SpeciesHide

Other Members of this group:
BernaliteFe(OH)3 · nH2O (n = 0.0 to 0.25)Orth. mmm (2/m 2/m 2/m) : Pmmn

Related Minerals - Nickel-Strunz GroupingHide

4.FC.05BernaliteFe(OH)3 · nH2O (n = 0.0 to 0.25)Orth. mmm (2/m 2/m 2/m) : Pmmn
4.FC.10NataniteFe2+[Sn(OH)6]Iso. m3m (4/m 3 2/m) : Pn3m
4.FC.10SchoenfliesiteMg[Sn(OH)6]Iso. m3 (2/m 3) : Pn3
4.FC.10WickmaniteMn2+[Sn(OH)6]Iso. m3 (2/m 3) : Pn3
4.FC.15JeanbandyiteFe3+xFe2+1-xSn(OH)6-xOx (1 ≥ x > 0.5)Tet. 4/m : P42/n
4.FC.15MopungiteNa[Sb5+(OH)6]Tet. 4/m : P42/n
4.FC.15TetrawickmaniteMn2+[Sn4+(OH)6]Tet. 4/m : P42/n
4.FC.20Ferronigerite-2N1S(Al,Fe,Zn)2(Al,Sn)6O11(OH)Trig. 3m (3 2/m) : P3m1
4.FC.20Magnesionigerite-6N6S(Mg,Al,Zn)3(Al,Sn,Fe)8O15(OH)Trig. 3m (3 2/m) : R3m
4.FC.20Magnesionigerite-2N1S(Mg,Al,Zn)2(Al,Sn)6O11(OH)Trig. 3m (3 2/m) : P3m1
4.FC.20Ferronigerite-6N6S(Al,Fe,Zn)3(Al,Sn,Fe)8O15(OH)Trig. 3m (3 2/m) : R3m
4.FC.20Zinconigerite-2N1S(Zn,Al,Mg)2(Al,Sn)6O11(OH)Trig. 3m (3 2/m) : P3m1
4.FC.20Zinconigerite-6N6S(Zn,Mg,Al)3(Al,Sn,Fe)8O15(OH)Trig. 3m (3 2/m) : R3m
4.FC.25Magnesiotaaffeite-2N’2SMg3Al8BeO16Hex. 6/mmm (6/m 2/m 2/m)

Related Minerals - Dana Grouping (8th Ed.)Hide · nH2O (n = 0.0 to 0.25)Orth. mmm (2/m 2/m 2/m) : Pmmn

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

7.7.2Cerianite-(Ce)(Ce4+,Th)O2Iso. m3m (4/m 3 2/m) : Fm3m
7.7.3AvicenniteTl2O3Iso. m3 (2/m 3) : Ia3

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 SöhngeiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Strunz, H. (1965) Söhngeit, Ga(OH)3, ein neues Mineral. Naturwissenschaften: 52: 493 (in German).
Fleischer, M. (1966) New mineral names. American Mineralogist: 51: 1815-1820.
Scott, J.D. (1971) Crystal structure of a new mineral, söhngeite. American Mineralogist: 56: 355-355.
Welch, M.D., Kleppe, A.K. (2016) Polymorphism of the hydroxide perovskite Ga(OH)3 and possible proton-driven transformational behaviour. Physics and Chemistry of Minerals: 43, 515-526.
Anthony, J.W., Bideaux, R.A., Bladh, K.W., Nichols, M.C., Eds. Handbook of Mineralogy, Mineralogical Society of America, Chantilly, VA 20151-1110, USA. http://www.handbookofmineralogy.org/ (2016)
Mitchell, R.H., Welch, M.D., Chakhmouradian, A.R. (2017) Nomenclature of the perovskite supergroup: A hierarchical system of classification based on crystal structure and composition. Mineralogical Magazine: 81: 411-461.

Internet Links for SöhngeiteHide

Localities for SöhngeiteHide

This 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.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - 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.
Namibia (TL)
  • Oshikoto Region
    • Tsumeb
Naturwissenschaften (1965): 52: 493; American Mineralogist (1966): 51: 1815.
Mineral and/or Locality  
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