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Rankachite

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Formula:
Ca
 
0.5
(V
4+
 
,V
5+
 
)(W
6+
 
,Fe
3+
 
)
 
2
O
 
8
(OH) · 2H
 
2
O
System:MonoclinicColour:Brown, yellow.
Lustre:ResinousHardness:
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

IMA status:Approved
Strunz 8th edition ID:7/C.34-10
Nickel-Strunz 10th (pending) edition ID:7.GB.25

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
G : Molybdates, Wolframates and Niobates
B : With additional anions and/or H2O
Dana 8th edition ID:49.3.6.1

49 : HYDRATED MOLYBDATES AND TUNGSTATES
3 : Hydrated Molybdates and Tungstates Containing Hydroxyl or Halogen
Hey's CIM Ref.: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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Type Occurrence of Rankachite

Type Locality:Clara Mine, Rankach valley, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany
Year of Discovery:1984

Physical Properties of Rankachite

Lustre: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 {P1 1 21/m} {P21/m} {P1 21/m 1}
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°
Maximum Birefringence:δ = 0.200

Chart 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:
Ca
 
0.5
(V
4+
 
,V
5+
 
)(W
6+
 
,Fe
3+
 
)
 
2
O
 
8
(OH) · 2H
 
2
O
Simplified for copy/paste:Ca0.5(V4+,V5+)(W6+,Fe3+)2O8(OH)·2H2O
Essential elements:Ca, H, O, V, W
All elements listed in formula:Ca, Fe, H, O, V, W

Relationship of Rankachite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
7.GB.05Lindgrenite
Cu
 
3
(MoO
 
4
)
 
2
(OH)
 
2
7.GB.10Szenicsite
Cu
 
3
(MoO
 
4
)(OH)
 
4
7.GB.15Cuprotungstite
Cu
 
2
(WO
 
4
)(OH)
 
2
7.GB.15UM1999-38-WO:CrV
(V, Cr, W, O, H) [V:Cr:W ratio about 2:1:3]
7.GB.20Phyllotungstite
(H
 
2
O,M)
 
x
(W,Fe)(O,OH)
 
3
· yH
 
2
O (M = Ca, Cs, Pb or K)
7.GB.30Ferrimolybdite
Fe
 
2
(MoO
 
4
)
 
3
· nH
 
2
O
7.GB.35Anthoinite
AlWO
 
3
(OH)
 
3
7.GB.35Mpororoite
WAlO
 
3
(OH)
 
3
· 2(H
 
2
O)
7.GB.40Obradovicite-KCu
[K
 
2
(H
 
2
O)
 
17
Cu(H
 
2
O)
 
6
][Mo
 
8
As
 
2
Fe
3+
3
O
 
34
(OH)
 
3
]
7.GB.45Mendozavilite-NaFe
[Na
 
2
(H
 
2
O)
 
15
Fe
3+
 
(H
 
2
O)
 
6
][Mo
 
8
P
 
2
Fe
3+
3
O
 
35
(OH)
 
2
]
7.GB.45Paramendozavilite
[KAl
 
4
(H
 
2
O)
 
30
][Mo
 
12
P
 
6
Fe
3+
6
O
 
60
(OH)
 
13
]
7.GB.50Tancaite-(Ce)
FeCe(MoO
 
4
)
 
3
·3H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
22.5.1Vauquelinite
Pb
 
2
Cu(CrO
 
4
)(PO
 
4
)(OH)
22.5.2Embreyite
Pb
 
5
(CrO
 
4
)
 
2
(PO
 
4
)
 
2
· H
 
2
O
22.5.3Cassedanneite
Pb
 
5
(CrO
 
4
)
 
2
(VO
 
4
)
 
2
· H
 
2
O
22.5.4Fornacite
Pb
 
2
Cu(CrO
 
4
)(AsO
 
4
)(OH)
22.5.5Molybdofornacite
Pb
 
2
Cu(MoO
 
4
,CrO
 
4
)(AsO
 
4
,PO
 
4
)(OH)
22.5.6Mendozavilite-NaFe
[Na
 
2
(H
 
2
O)
 
15
Fe
3+
 
(H
 
2
O)
 
6
][Mo
 
8
P
 
2
Fe
3+
3
O
 
35
(OH)
 
2
]
22.5.7Paramendozavilite
[KAl
 
4
(H
 
2
O)
 
30
][Mo
 
12
P
 
6
Fe
3+
6
O
 
60
(OH)
 
13
]
22.5.8Betpakdalite-CaCa
[Ca
 
2
(H
 
2
O)
 
17
Ca(H
 
2
O)
 
6
][Mo
6+
8
As
5+
2
Fe
3+
3
O
 
36
(OH)]
22.5.9Betpakdalite-NaCa
[Na
 
2
(H
 
2
O)
 
17
Ca(H
 
2
O)
 
6
][Mo
6+
8
As
5+
2
Fe
3+
3
O
 
34
(OH)
 
3
]
22.5.10Obradovicite-KCu
[K
 
2
(H
 
2
O)
 
17
Cu(H
 
2
O)
 
6
][Mo
 
8
As
 
2
Fe
3+
3
O
 
34
(OH)
 
3
]
22.5.11Melkovite
[Ca
 
2
(H
 
2
O)
 
15
Ca(H
 
2
O)
 
6
][Mo
 
8
P
 
2
Fe
3+
3
O
 
36
(OH)]
22.5.13Olmsteadite
KFe
2+
2
(Nb
5+
 
,Ta
5+
 
)(PO
 
4
)
 
2
O
 
2
· 2H
 
2
O
22.5.14Johnwalkite
K(Mn
2+
 
,Fe
2+
 
,Fe
3+
 
)
 
2
(Nb
5+
 
,Ta
5+
 
)(PO
 
4
)
 
2
O
 
2
· 2(H
 
2
O,OH)

Other Names for Rankachite

Synonyms:
IMA1983-044
Other Languages:
German:Rankachit
Spanish:Rankachita

Other Information

Health Warning: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

Search Engines:
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  • External Links:
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  • Look for Rankachite on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Rankachite details from Handbook of Mineralogy (PDF)
  • Mineral Dealers:
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  • Localities for Rankachite

    The 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. ? 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
     
    • 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)
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    Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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