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Rankachite

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Formula:
Ca0.5(V4+,V5+)(W6+,Fe3+)2O8(OH) · 2H2O
System:
Monoclinic
Colour:
Brown, yellow.
Lustre:
Resinous
Hardness:
Name:
Named after the Rankach valley, in which the Clara mine (type locality) is located.
This page provides mineralogical data about Rankachite.

Classification of Rankachite

Approved
7.GB.25

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
G : Molybdates, Wolframates and Niobates
B : With additional anions and/or H2O
49.3.6.1

49 : HYDRATED MOLYBDATES AND TUNGSTATES
3 : Hydrated Molybdates and Tungstates Containing Hydroxyl or Halogen
22.5.12

22 : Phosphates, Arsenates or Vanadates with other Anions
5 : Phosphates, arsenates or vanadates with chromate, molybdate, niobate or tantalate
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http://www.mindat.org/min-3361.html
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Type Occurrence of Rankachite

Year of Discovery:
1984

Physical Properties of Rankachite

Resinous
Colour:
Brown, yellow.
Hardness (Mohs):
Cleavage:
Perfect
Perfect cleavage parallel to {001}

Crystallography of Rankachite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/m
Cell Parameters:
a = 5.479Å, b = 8.144Å, c = 10.627Å
β = 98.22°
Ratio:
a:b:c = 0.673 : 1 : 1.305
Unit Cell Volume:
V 469.3 ų
Z:
2
Morphology:
Tabular on {001} and elongated along [100].
Twinning:
None observed.

Optical Data of Rankachite

Type:
Biaxial (-)
RI values:
nα = 1.770 nβ = 1.925 nγ = 1.970
2V:
Measured: 58° , Calculated: 52°
Max Birefringence:
δ = 0.200
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Very High
Dispersion:
relatively strong

Chemical Properties of Rankachite

Formula:
Ca0.5(V4+,V5+)(W6+,Fe3+)2O8(OH) · 2H2O
Essential elements:
All elements listed in formula:

Relationship of Rankachite to other Species

7.GB.05LindgreniteCu3(MoO4)2(OH)2
7.GB.10SzenicsiteCu3(MoO4)(OH)4
7.GB.15CuprotungstiteCu2(WO4)(OH)2
7.GB.15UM1999-38-WO:CrV(V, Cr, W, O, H) [V:Cr:W ratio about 2:1:3]
7.GB.20Phyllotungstite(H2O,M)x(W,Fe)(O,OH)3 · yH2O (M = Ca, Cs, Pb or K)
7.GB.30FerrimolybditeFe2(MoO4)3 · nH2O
7.GB.35AnthoiniteAlWO3(OH)3
7.GB.35MpororoiteWAlO3(OH)3 · 2(H2O)
7.GB.40Obradovicite-KCu[K2(H2O)17Cu(H2O)6][Mo8As2Fe33+O34(OH)3]
7.GB.45Mendozavilite-NaFe[Na2(H2O)15Fe3+(H2O)6][Mo8P2Fe33+O35(OH)2]
7.GB.45ParamendozaviliteNaAl4Fe7(PO4)5(PMo12O40)(OH)16 · 56H2O
7.GB.50Tancaite-(Ce)FeCe(MoO4)3·3H2O
22.5.1VauquelinitePb2Cu(CrO4)(PO4)(OH)
22.5.2EmbreyitePb5(CrO4)2(PO4)2 · H2O
22.5.3CassedanneitePb5(CrO4)2(VO4)2 · H2O
22.5.4FornacitePb2Cu(CrO4)(AsO4)(OH)
22.5.5MolybdofornacitePb2Cu(MoO4,CrO4)(AsO4,PO4)(OH)
22.5.6Mendozavilite-NaFe[Na2(H2O)15Fe3+(H2O)6][Mo8P2Fe33+O35(OH)2]
22.5.7ParamendozaviliteNaAl4Fe7(PO4)5(PMo12O40)(OH)16 · 56H2O
22.5.8Betpakdalite-CaCa[Ca2(H2O)17Ca(H2O)6][Mo86+As25+Fe33+O36(OH)]
22.5.9Betpakdalite-NaCa[Na2(H2O)17Ca(H2O)6][Mo86+As25+Fe33+O34(OH)3]
22.5.10Obradovicite-KCu[K2(H2O)17Cu(H2O)6][Mo8As2Fe33+O34(OH)3]
22.5.11Melkovite[Ca2(H2O)15Ca(H2O)6][Mo8P2Fe33+O36(OH)]
22.5.13OlmsteaditeKFe22+(Nb5+,Ta5+)(PO4)2O2 · 2H2O
22.5.14JohnwalkiteK(Mn2+,Fe2+,Fe3+)2(Nb5+,Ta5+)(PO4)2O2 · 2(H2O,OH)

Other Names for Rankachite

Name in Other Languages:
German:Rankachit
Spanish:Rankachita

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.

References for Rankachite

Reference List:
Walenta, K. & Dunn, P. J. (1984): Rankachit, ein neues Mineral aus der Grube Clara im mittleren Schwarzwald. Neues Jahrbuch für Mineralogie, Monatshefte (1984): (7): 289-295. (in German).

American Mineralogist (1985): 70: 876.

Kolitsch, U. (1999) Ein neues, Vanadium, Chrom und Wolfram enthaltendes Mineral aus einer Rankachit-Paragenese von der Grube Clara im mittleren Schwarzwald. Aufschluss 50, 23-32. (in German).

Kolitsch, U. and M. Götzinger (2000): Some new finds from the Clara mine, middle Black Forest: eulytite, namibite, volborthite, gearksutite, spertiniite, monazite-(La), protasite, sainfeldite, cyanotrichite and vauquelinite. Erzgräber 14, 33-47. (in German).

Walenta, K. & Theye, T. (2005): Iron-poor rankachite from the Clara mine. Der Erzgräber, 19, 58-62 (in German with English abstract).

Kolitsch, U. and G. Giester (2006): Rankachite, an unusual oxidic Ca-Fe-V-W-mineral from the Clara mine, Central Black Forest: crystal structure and revision of symmetry, unit cell and chemical formula. Poster, Annual Meeting of the DGK, Freiburg, Germany, April 3 - 6, 2006; abstract in Z. Kristallogr., Suppl. No. 24, 138.

Internet Links for Rankachite

Localities for Rankachite

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.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? 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.
Germany (TL)
 
  • Baden-Württemberg
    • Black Forest
      • Wolfach
        • Oberwolfach
          • Rankach valley
Neues Jahrb.Min.,Mh,(1984) 289-295; Walenta, K. (1992): Die Mineralien des Schwarzwaldes. Chr. Weise Verlag, München, 336 pp. (in German)
Mineral and/or Locality  
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