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Phyllotungstite

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Big Photo

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

Show Phyllotungstite Photos (3)



Formula:
(H
 
2
O,M)
 
x
(W,Fe)(O,OH)
 
3
 · yH
 
2
O (M = Ca, Cs, Pb or K)
Based on the assumption that H2O fills up 10 A sites.
System:HexagonalColour:Yellow
Hardness:2
Name:For the appearance (Greek phyllos) and the chemical composition (tungsten).


Structurally and chemically similar to Pittongite.
Orthorhombic-pseudohexagonal.

Originally proposed formula is HCaFe3+3(WO4)6.10H2O (Walenta, 1984). Formula revised by Grey et al. (2006).

Note: Pb-, K- and Cs-dominant members have been described by Walenta (2008) and Walenta & Theye (2010a,b). The K-member is pseudohexagonal and forms aragonite-like drillings. Re-analysis of phyllotungstite type material showed that Cs and Pb are also present, in variable amounts (Walenta, 2008).

Compare also ferritungstite.

Classification of Phyllotungstite

IMA status:Approved 1984
Strunz 8th edition ID:6/G.02-40
Nickel-Strunz 10th (pending) edition ID:7.GB.20

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
G : Molybdates, Wolframates and Niobates
B : With additional anions and/or H2O
Dana 8th edition ID:49.2.4.1

49 : HYDRATED MOLYBDATES AND TUNGSTATES
2 : Hydrated Normal Molybdates and Tungstates
Hey's CIM Ref.:27.4.17

27 : Sulphites, Chromates, Molybdates and Tungstates
4 : Tungstates
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Type Occurrence of Phyllotungstite

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

Physical Properties of Phyllotungstite

Lustre:Pearly
Diaphaneity (Transparency):Translucent
Colour:Yellow
Hardness (Mohs):2

Crystallography of Phyllotungstite

Crystal System:Hexagonal
Class (H-M):6/mmm (6/m 2/m 2/m) - Dihexagonal Dipyramidal
Space Group:P63/mmc {P63/m 2/m 2/c}
Cell Parameters:a = 7.31(3) Å, c = 19.55(1) Å
Ratio:a:c = 1 : 2.674
Unit Cell Volume:V 904.72 ų (Calculated from Unit Cell)
Morphology:Platy.
Comment:Originally given cell was orthorhombic, with 7.29, 12.59 and 19.55. Since the mineral is optically biaxial, the space group given by Grey (2006) might refer to an average cell (due to twinning?).
X-Ray Powder Diffraction:
d-spacingIntensity
6.33 (7)
6.01 (6)
3.25 (8)
3.13 (10)
2.92 (7)
2.45 (7)
1.822 (8)

Optical Data of Phyllotungstite

Type:Biaxial (-)
RI values: nα = 2.100 nβ = 2.183 - 2.185 nγ = 2.185
Maximum Birefringence:δ = 0.085

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Very High
Dispersion:r < v extreme

Chemical Properties of Phyllotungstite

Formula:
(H
 
2
O,M)
 
x
(W,Fe)(O,OH)
 
3
 · yH
 
2
O (M = Ca, Cs, Pb or K)


Based on the assumption that H2O fills up 10 A sites.
Essential elements:Ca, H, O, W
All elements listed in formula:Ca, Cs, Fe, H, K, O, Pb, W

Relationship of Phyllotungstite 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.25Rankachite
Ca
 
0.5
(V
4+
 
,V
5+
 
)(W
6+
 
,Fe
3+
 
)
 
2
O
 
8
(OH) · 2H
 
2
O
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:

- +
27.4.1Cuprotungstite
Cu
 
2
(WO
 
4
)(OH)
 
2
27.4.2Scheelite
Ca(WO
 
4
)
27.4.4Anthoinite
AlWO
 
3
(OH)
 
3
27.4.5Mpororoite
WAlO
 
3
(OH)
 
3
 · 2(H
 
2
O)
27.4.6Yttrotungstite-(Y)
YW
 
2
O
 
6
(OH)
 
3
27.4.7Yttrotungstite-(Ce)
(Ce,Nd,Y)W
 
2
O
 
6
(OH)
 
3
27.4.8Stolzite
Pb(WO
 
4
)
27.4.9Raspite
Pb(WO
 
4
)
27.4.10Russellite
Bi
 
2
WO
 
6
27.4.11Pinalite
Pb
 
3
WO
 
5
Cl
 
2
27.4.12Uranotungstite
(Fe
2+
 
,Ba,Pb)(UO
 
2
)
 
2
(WO
 
4
)(OH)
 
4
 · 12H
 
2
O
27.4.13Hübnerite
MnWO
 
4
27.4.14Ferberite
FeWO
 
4
27.4.15Wolframite
(Fe
2+
 
)WO
 
4
 
 
to (Mn
2+
 
)WO
 
4
27.4.16Ferritungstite
27.4.18Qitianlingite
(Fe,Mn)
 
2
(Nb,Ta)
 
2
WO
 
10

Other Names for Phyllotungstite

Synonyms:
IMA1984-018
Other Languages:
German:Phyllotungstit

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 Phyllotungstite

Reference List:

- +
Walenta, K. (1984): Phyllotungstit, ein neues sekundäres Wolframmineral aus der Grube Clara im mittleren Schwarzwald. Neues Jahrb. Mineral., Monatsh. 1984, 529-535. (in German).

American Mineralogist (1986): 71: 846.

Grey, I.E., Birch, W.D., Bougerol, C., Mills, S.J. (2006): Unit-cell intergrowth of pyrochlore and hexagonal tungsten bronze structures in secondary tungsten minerals. Journal of Solid State Chemistry, 179, 3860-3869.

Birch, W.D., Grey, I.E., Mills, S.J., Bougerol, C., Pring, A., Ansermet, S. (2007): Pittongite, a new secondary tungstate from Pittong, Victoria, Australia. Canadian Mineralogist, 45, 857-864.

Walenta, K. (2008): Pittongit und Phyllotungstit. Erzgräber, 20, 103-107 (in German).

Walenta, K. & Theye, T. (2010a): Ein dem Phyllotungstit nahestehendes cäsiumreiches Mineral von der Grube Clara bei Oberwolfach im mittleren Schwarzwald. Erzgräber 24, 1-8.

Walenta, K. & Theye, T. (2010): Ein bleireiches und kaliumreiches Phyllotungstitmineral von der Grube Clara im mittleren Schwarzwald. Erzgräber 24, 66-76 (in German).

Internet Links for Phyllotungstite

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    • Localities for Phyllotungstite

    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) 529-535; Walenta, K. (1992): Die Mineralien des Schwarzwaldes. Chr. Weise Verlag, München, 336 pp. (in German)
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