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Rankachite

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Clara Mine, Rankach valley, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany
© Stephan Wolfsried

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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:2½
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):2½
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
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
Al
 
2
(WO
 
4
)
 
2
O · 6H
 
2
O
7.GB.40Obradovicite
H
 
4
(K,Na)CuFe
 
2
(MoO
 
4
)
 
5
(AsO
 
4
) · 12H
 
2
O
7.GB.45Mendozavilite
Na(Ca,Mg)
 
2
Fe
3+
6
(PMo
 
11
O
 
39
)(PO
 
4
)
 
2
(OH,Cl)
 
10
 · 33H
 
2
O
7.GB.45Paramendozavilite
NaAl
 
4
Fe
3+
7
(PMo
 
12
O
 
40
)(PO
 
4
)
 
5
(OH)
 
16
 · 56H
 
2
O
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
Na(Ca,Mg)
 
2
Fe
3+
6
(PMo
 
11
O
 
39
)(PO
 
4
)
 
2
(OH,Cl)
 
10
 · 33H
 
2
O
22.5.7Paramendozavilite
NaAl
 
4
Fe
3+
7
(PMo
 
12
O
 
40
)(PO
 
4
)
 
5
(OH)
 
16
 · 56H
 
2
O
22.5.8Betpakdalite
{Mg(H
 
2
O)
 
6
}Ca
 
2
(H
 
2
O)
 
13
[Mo
6+
8
As
5+
2
Fe
3+
3
O
 
36
(OH)](H
 
2
O)
 
4
22.5.9Natrobetpakdalite
(Na
 
2
,Ca)Fe
 
2
(As
 
2
Mo
 
6
O
 
28
) · 15H
 
2
O
22.5.10Obradovicite
H
 
4
(K,Na)CuFe
 
2
(MoO
 
4
)
 
5
(AsO
 
4
) · 12H
 
2
O
22.5.11Melkovite
CaFe
3+
2
Mo
 
5
(PO
 
4
)
 
2
O
 
10
(OH)
 
12
 · 8H
 
2
O
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

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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.
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    (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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