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Gengenbachite

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Formula:
KFe3+3(HPO4)4(H2PO4)2 · 6H2O
Colour:
Pale brown
Lustre:
Vitreous
Hardness:
2
Specific Gravity:
2.4
Crystal System:
Trigonal
Name:
For the town of Gengenbach, adjacent to the type locality.
This page provides mineralogical data about Gengenbachite.


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Classification of GengenbachiteHide

Approved
Approval Year:
2006
8.CA.65

8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
A : With small and large/medium cations

Physical Properties of GengenbachiteHide

Vitreous
Transparency:
Translucent
Colour:
Pale brown
Streak:
White
Hardness:
Hardness Data:
Estimated
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Irregular/Uneven
Density:
2.4(5) g/cm3 (Measured)    2.43(2) g/cm3 (Calculated)

Optical Data of GengenbachiteHide

Type:
Uniaxial (+)
RI values:
nω = 1.592() nε = 1.596(2)
Max Birefringence:
δ = 0.004
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Optical Extinction:
Anomalous pale brownish interference colours.

Chemical Properties of GengenbachiteHide

Formula:
KFe3+3(HPO4)4(H2PO4)2 · 6H2O
IMA Formula:
KFe3(H2PO4)2(HPO4)4 · 6H2O

Crystallography of GengenbachiteHide

Crystal System:
Trigonal
Class (H-M):
3m - Ditrigonal Pyramidal
Space Group:
P3 1c
Cell Parameters:
a = 9.12(1) Å, c = 16.84(2) Å
Ratio:
a:c = 1 : 1.846
Unit Cell V:
1,213.00 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Simple hexagonal prisms.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
7.89(4)
7.16(10)
4.57(7)
3.57(5)
3.23(6)
3.09(8)
2.87(4)
2.81(5)

Type Occurrence of GengenbachiteHide

Synonyms of GengenbachiteHide

Other Language Names for GengenbachiteHide

Related Minerals - Nickel-Strunz GroupingHide

8.CA.DavidlloyditeZn3(AsO4)2·4H2O Tric. 1 : P1
8.CA.ApexiteNaMg(PO4)·9H2OTric. 1 : P1
8.CA.05FransoletiteCa3Be2(PO4)2(HPO4)2 · 4H2OMon.
8.CA.05ParafransoletiteCa3Be2(PO4)2(HPO4)2 · 4H2OTric. 1 : P1
8.CA.10EhrleiteCa4Be3Zn2(PO4)6 · 9H2OTric. 1 : P1
8.CA.15FaheyiteBe2Mn2+Fe3+2(PO4)4 · 6H2OTrig. 3 2 : P31 2 1
8.CA.20GainesiteNa(Na,K)(Be,Li)Zr2(PO4)4 · 1.5-2H2OTet. 4mm : I41md
8.CA.20MccrillisiteNaCs(Be,Li)Zr2(PO4)4 · 1-2H2OTet. 4/mmm (4/m 2/m 2/m) : I41/amd
8.CA.20SelwyniteNaK(Be,Al)Zr2(PO4)4 · 2H2OTet.
8.CA.25PahasapaiteLi8(Ca,Li,K)10.5Be24(PO4)24 · 38H2OIso. 2 3 : I2 3
8.CA.30HopeiteZn3(PO4)2 · 4H2OOrth. mmm (2/m 2/m 2/m) : Pnma
8.CA.30ArsenohopeiteZn3(AsO4)2 · 4H2OOrth. mmm (2/m 2/m 2/m) : Pnma
8.CA.35WarikahniteZn3(AsO4)2 · 2H2OTric.
8.CA.40PhosphophylliteZn2Fe(PO4)2 · 4H2OMon. 2/m : P21/b
8.CA.45ParascholziteCaZn2(PO4)2 · 2H2OMon.
8.CA.45ScholziteCaZn2(PO4)2 · 2H2OOrth. mmm (2/m 2/m 2/m) : Pbcm
8.CA.50KeyiteCu2+3Zn4Cd2(AsO4)6 · 2H2OMon. 2/m
8.CA.55PushcharovskiteK0.6Cu18(AsO4)(HAsO4)10(H2AsO4)4(OH)9.6·18.6H2OTric.
8.CA.60ProsperiteCa2Zn4(AsO4)4 · H2OMon.
8.CA.70ParahopeiteZn3(PO4)2 · 4H2OTric. 1 : P1

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 GengenbachiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Anisimova, N., Chudinova, N. & Serafin, M. (1997): Preparation and crystal structure of potassium iron hydrogen phosphate KFe3(HPO4)2(H2PO4)6.4H2O. Zeitschrift für Anorganische und Allgemeine Chemie 623, 1708-1714.
Walenta, K. (1998): Neue Mineralfunde aus dem Schwarzwald. 7. Folge, 2. Teil. Lapis, 23(12), 43-48.
Walenta K. & Theye, T. (2004): KFe3+3[(H2PO4)2|(HPO4)4]•6H2O, ein zweites neues Phosphatmineral von der Grube Silberbrünnle im mittleren Schwarzwald. Der Erzgräber, 18(1), 17-23. (in German) [abstracted in Am. Mineral. 90, 1228(2005)]
Walenta, K., Theye, T. & Hatert, F. (2007): Gengenbachit, KFe3+3(H2PO4)2(HPO4)4•6H2O, ein zweites neues Phosphatmineral von der Grube Silberbrünnle im mittleren Schwarzwald, nunmehr eine anerkannte neue Mineralart. Aufschluss, 58, 125-128. (in German)
WALENTA, K. und THEYE, Th. (2009): H-reicher Gengenbachit von der Grube Silberbrünnle bei Gengenbach im mittleren Schwarzwald: Eine neue Mineralart oder nur eine Varietät ? Erzgräber 23, 37-40 (in German).

Internet Links for GengenbachiteHide

Localities for GengenbachiteHide

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.
Germany (TL)
 
  • Baden-Württemberg
    • Black Forest
      • Gengenbach
        • Haigerach valley
Walenta K. & Theye, T. (2004): KFe3+3[(H2PO4)2|(HPO4)4]•6H2O, ein zweites neues Phosphatmineral von der Grube Silberbrünnle im mittleren Schwarzwald. Der Erzgräber, 18(1), 17-23.
Mineral and/or Locality  
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