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Söhngeite
A valid IMA mineral species
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About Söhngeite
A. P. Gerhard Söhnge
Formula:
Ga(OH)3
Colour:
Brown, white, pale yellow, pale brown, pale greenish yellow
Hardness:
4 - 4½
Specific Gravity:
3.84
Crystal System:
Tetragonal
Name:
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.
Structurally a hydroxide perovskite. The structure has 5 independent OH groups and is based on Ga(OH)6 octahedra.
Name Encoding
ASCII-7:
Sohngeite
Unique Identifiers
Mindat ID:
3709
Long-form identifier:
mindat:1:1:3709:5
IMA Classification of Söhngeite
Approved
Approval year:
1965
Classification of Söhngeite
4.FC.05
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
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
6.3.5.2
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
3 : X(OH)3
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
3 : X(OH)3
7.7.1
7 : Oxides and Hydroxides
7 : Oxides of Group III metals other than Al
7 : Oxides and Hydroxides
7 : Oxides of Group III metals other than Al
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Söh | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Söhngeite
Transparency:
Transparent
Colour:
Brown, white, pale yellow, pale brown, pale greenish yellow
Comment:
Semitransparent
Hardness:
4 - 4½ on Mohs scale
Density:
3.84 g/cm3 (Measured) 3.847 g/cm3 (Calculated)
Optical Data of Söhngeite
Type:
Isotropic
RI values:
n = 1.736
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Chemistry of Söhngeite
Mindat Formula:
Ga(OH)3
Elements listed:
Crystallography of Söhngeite
Crystal System:
Tetragonal
Cell Parameters:
a = 7.4546 Å, c = 7.3915 Å
Ratio:
a:c = 1 : 0.992
Unit Cell V:
410.75 ų (Calculated from Unit Cell)
Twinning:
Trillings of composite flattened, curved crystals; interpenetrant at right angles according to an unknown law.
Comment:
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 Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.74 Å | (100) |
| 1.669 Å | (70) |
| 2.63 Å | (60) |
| 1.525 Å | (60) |
| 1.867 Å | (40) |
| 2.15 Å | (35) |
| 2.36 Å | (30) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] |
Type Occurrence of Söhngeite
General Appearance of Type Material:
Crystalline, twinned groups and aggregates, up to 1 cm; single crystals are very rare.
Place of Conservation of Type Material:
Institut für Mineralogie und Kristallographie, Technische Universität, Berlin, Germany, numbers 86/68, 89/122.
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 Söhngeite
Other Language Names for Söhngeite
Relationship of Söhngeite to other Species
Other Members of Söhngeite Subgroup:
| Bernalite | Fe(OH)3 · nH2O (n = 0.0 to 0.25) | Orth. mmm(2/m2/m2/m) : Pmmn |
| Dzhalindite | In(OH)3 | Iso. m3(2/m3) : Im3 |
Common Associates
Associations Based on Photo Data:
| 7 photos of Söhngeite associated with Germanite | Cu13Fe2Ge2S16 |
| 4 photos of Söhngeite associated with Chalcocite | Cu2S |
| 3 photos of Söhngeite associated with Gallite | CuGaS2 |
| 3 photos of Söhngeite associated with Renierite | (Cu+,Zn)11Fe4(Ge4+,As5+)2S16 |
| 2 photos of Söhngeite associated with Tennantite Subgroup | Cu6(Cu4C2+2)As4S12S |
Related Minerals - Strunz-mindat Grouping
| 4.FC.05 | Dzhalindite | In(OH)3 |
| 4.FC.05 | Bernalite | Fe(OH)3 · nH2O (n = 0.0 to 0.25) |
| 4.FC.10 | Mushistonite | (Cu,Zn,Fe2+)[Sn(OH)6] |
| 4.FC.10 | Natanite | Fe2+[Sn(OH)6] |
| 4.FC.10 | Burtite | Ca[Sn(OH)6] |
| 4.FC.10 | Vismirnovite | Zn[Sn(OH)6] |
| 4.FC.10 | Wickmanite | Mn2+[Sn(OH)6] |
| 4.FC.10 | Schoenfliesite | Mg[Sn(OH)6] |
| 4.FC.15 | Jeanbandyite | Fe3+Sn(OH)5O |
| 4.FC.15 | Tetrawickmanite | Mn2+[Sn4+(OH)6] |
| 4.FC.15 | Nancyrossite | FeGeO6H5 |
| 4.FC.15 | Zincostottite | ZnGe(OH)6 |
| 4.FC.15 | Stottite | Fe2+[Ge4+(OH)6] |
| 4.FC.15 | Mopungite | Na[Sb5+(OH)6] |
| 4.FC.20 | Ferronigerite-2N1S | (Al,Fe,Zn)2(Al,Sn)6O11(OH) |
| 4.FC.20 | Magnesionigerite-6N6S | (Mg,Al,Zn)3(Al,Sn,Fe)8O15(OH) |
| 4.FC.20 | Magnesionigerite-2N1S | (Mg,Al,Zn)2(Al,Sn)6O11(OH) |
| 4.FC.20 | Ferronigerite-6N6S | (Al,Fe,Zn)3(Al,Sn,Fe)8O15(OH) |
| 4.FC.20 | Zinconigerite-2N1S | (Zn,Al,Mg)2(Al,Sn)6O11(OH) |
| 4.FC.20 | Zinconigerite-6N6S | Zn3Sn2Al16O30(OH)2 |
| 4.FC.25 | Magnesiotaaffeite-6N’3S | Mg2BeAl6O12 |
| 4.FC.25 | Magnesiotaaffeite-2N’2S | Mg3Al8BeO16 |
| 4.FC.25 | Ferrotaaffeite-2N’2S | Be(Fe,Mg,Zn)3Al8O16 |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Söhngeite
mindat.org URL:
https://www.mindat.org/min-3709.html
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Please feel free to link to this page.
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References for Söhngeite
Reference List:
Strunz, H. (1965) Söhngeit, Ga(OH)3, ein neues Mineral. Die Naturwissenschaften, 52 (17). 493 doi:10.1007/bf00646572
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 (7). 515-526 doi:10.1007/s00269-016-0812-y
Localities for Söhngeite
Showing 1 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and 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).
All localities listed without proper references should be considered as questionable.
Namibia (TL) | |
| Strunz (1965) +1 other reference |
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Tsumeb Mine, Tsumeb, Oshikoto Region, Namibia