Zwieselite
A valid IMA mineral species - grandfathered
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About Zwieselite
Formula:
Fe2+2(PO4)F
Colour:
Dark brown; black (altered)
Lustre:
Sub-Vitreous, Resinous, Greasy
Hardness:
5 - 5½
Specific Gravity:
3.89 - 3.97
Crystal System:
Monoclinic
Member of:
Name:
Named in 1841 by August Breithaupt for the town of Zwiesel (Bavaria, Germany) where the mineral was found.
Type Locality:
Isostructural with:
Triplite-Zwieselite Series.
The Fe2+ analogue of the Mn end-member triplite.
Also the Fe2+ analogue of wagnerite (not isotypic).
The Fe2+ analogue of the Mn end-member triplite.
Also the Fe2+ analogue of wagnerite (not isotypic).
Unique Identifiers
Mindat ID:
4436
Long-form identifier:
mindat:1:1:4436:9
IMA Classification of Zwieselite
Approved, 'Grandfathered' (first described prior to 1959)
IMA status notes:
Redefined by the IMA
IMA Formula:
Fe2+2PO4F
First published:
1841
Approval history:
Redefined IMA03-C.
Classification of Zwieselite
8.BB.10
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
B : With only medium-sized cations, (OH, etc.):RO4 about 1:1
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
B : With only medium-sized cations, (OH, etc.):RO4 about 1:1
41.6.1.1
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
6 : A2(XO4)Zq
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
6 : A2(XO4)Zq
22.1.25
22 : Phosphates, Arsenates or Vanadates with other Anions
1 : Phosphates, arsenates or vanadates with fluoride
22 : Phosphates, Arsenates or Vanadates with other Anions
1 : Phosphates, arsenates or vanadates with fluoride
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Zwi | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Zwieselite
Sub-Vitreous, Resinous, Greasy
Transparency:
Translucent
Colour:
Dark brown; black (altered)
Streak:
White to tan
Hardness:
5 - 5½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
{001} good, {010} fair, {100} poor.
{001} good, {010} fair, {100} poor.
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
3.89 - 3.97 g/cm3 (Measured) 3.92 g/cm3 (Calculated)
Optical Data of Zwieselite
Type:
Biaxial (+)
RI values:
nα = 1.686 - 1.696 nβ = 1.690 - 1.704 nγ = 1.703 - 1.713
2V:
Measured: 58° , Calculated: 60°
Birefringence:
0.017
Max. Birefringence:
δ = 0.017
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r > v
Pleochroism:
Visible
Comments:
Yellow brown to reddish brown.
Chemistry of Zwieselite
Mindat Formula:
Fe2+2(PO4)F
Element Weights:
Elements listed:
Common Impurities:
Mg,Ca
Crystallography of Zwieselite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Cell Parameters:
a = 12.085 Å, b = 6.536 Å, c = 9.910 Å
β = 105.63°
β = 105.63°
Ratio:
a:b:c = 1.849 : 1 : 1.516
Unit Cell V:
753.82 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Usually massive, morphological crystals unknown.
Comment:
I2/a
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0012458 | Zwieselite | Yakubovich O V, Simonov M A, Matvienko E N, Belov N V (1978) The crystal structure of the synthetic finite Fe-term of the series triplite - zwieselite Fe2(PO4)F Doklady Akademii Nauk SSSR 238 576-579 | 1978 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.695 Å | (50) |
| 3.431 Å | (40) |
| 3.257 Å | (70) |
| 3.053 Å | (90) |
| 2.874 Å | (100) |
| 2.120 Å | (40) |
| 2.024 Å | (40) |
Comments:
Horni Slavkov, Czech Republic.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Type Occurrence of Zwieselite
Place of Conservation of Type Material:
No designated type specimen.
Geological Setting of Type Material:
Granite pegmatite.
Synonyms of Zwieselite
Other Language Names for Zwieselite
Relationship of Zwieselite to other Species
Member of:
Other Members of Triplite Group:
| Triplite | Mn2+2(PO4)F | Mon. 2/m |
| Triploidite | Mn2+2(PO4)(OH) | Mon. 2/m : P2/b |
| Wolfeite | Fe2+2(PO4)(OH) | Mon. 2/m : P21/b |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 5 photos of Zwieselite associated with Triphylite | LiFe2+PO4 |
| 5 photos of Zwieselite associated with Quartz | SiO2 |
| 4 photos of Zwieselite associated with Rockbridgeite | (Fe2+0.5Fe3+0.5)2Fe3+3(PO4)3(OH)5 |
| 3 photos of Zwieselite associated with Morinite | NaCa2Al2(PO4)2(OH)F4 · 2H2O |
| 3 photos of Zwieselite associated with Leucophosphite | KFe3+2(PO4)2(OH) · 2H2O |
| 2 photos of Zwieselite associated with Rittmannite | {(Mn2+,Ca)}{Mn2+}{(Fe2+,Mn2+,Mg)2}{(Al,Fe3+)2}(PO4)4(OH)2 · 8H2O |
| 2 photos of Zwieselite associated with Whitmoreite | Fe2+Fe3+2(PO4)2(OH)2 · 4H2O |
| 2 photos of Zwieselite associated with Triplite | Mn2+2(PO4)F |
| 2 photos of Zwieselite associated with Phosphosiderite | FePO4 · 2H2O |
| 2 photos of Zwieselite associated with 'Apatite' | Ca5(PO4)3A |
Related Minerals - Strunz-mindat Grouping
| 8.BB. | Moabite | NiFe3+(PO4)O |
| 8.BB. | Tilasite | CaMg(AsO4)F |
| 8.BB. | Paulgrothite | Cu9Fe3+O4(PO4)4Cl3 |
| 8.BB. | Karlditmarite | Cu9O4(PO4)2(SO4)2 |
| 8.BB. | Milkovoite | Cu4O(PO4)(AsO4) |
| 8.BB.X | Arsenowagnerite | Mg2(AsO4)F |
| 8.BB.05 | Tavorite | LiFe3+(PO4)(OH) |
| 8.BB.05 | Amblygonite | LiAl(PO4)F |
| 8.BB.05 | Montebrasite | LiAl(PO4)(OH) |
| 8.BB.10 | Triplite | Mn2+2(PO4)F |
| 8.BB.15 | 'Unnamed (Sb-analogue of Auriacusite)' | Fe3+Cu2+[(Sb,As)O4]O |
| 8.BB.15 | Joosteite | Mn2+(Mn3+,Fe3+)(PO4)O |
| 8.BB.15 | Hydroxylwagnerite | Mg2(PO4)(OH) |
| 8.BB.15 | Wagnerite | Mg2(PO4)F |
| 8.BB.15 | Stanĕkite | (Mn2+,Fe2+,Mg)Fe3+(PO4)O |
| 8.BB.15 | Triploidite | Mn2+2(PO4)(OH) |
| 8.BB.15 | Sarkinite | Mn2+2(AsO4)(OH) |
| 8.BB.15 | Wolfeite | Fe2+2(PO4)(OH) |
| 8.BB.20 | Holtedahlite | Mg2(PO4)(OH) |
| 8.BB.20 | Satterlyite | (Fe2+,Mg,Fe)12(PO4)5(PO3OH)(OH,O)6 |
| 8.BB.25 | Althausite | Mg4(PO4)2(OH,O)(F,◻) |
| 8.BB.30 | Zincolivenite | CuZn(AsO4)(OH) |
| 8.BB.30 | Adamite | Zn2(AsO4)(OH) |
| 8.BB.30 | Libethenite | Cu2(PO4)(OH) |
| 8.BB.30 | Zincolibethenite | CuZn(PO4)(OH) |
| 8.BB.30 | Eveite | Mn2+2(AsO4)(OH) |
| 8.BB.30 | Olivenite | Cu2(AsO4)(OH) |
| 8.BB.30 | Auriacusite | Fe3+Cu2+(AsO4)O |
| 8.BB.35 | Paradamite | Zn2(AsO4)(OH) |
| 8.BB.35 | Tarbuttite | Zn2(PO4)(OH) |
| 8.BB.40 | Barbosalite | Fe2+Fe3+2(PO4)2(OH)2 |
| 8.BB.40 | Scorzalite | Fe2+Al2(PO4)2(OH)2 |
| 8.BB.40 | Lazulite | MgAl2(PO4)2(OH)2 |
| 8.BB.40 | Meizhouite | Fe2+V3+2(PO4)2(OH)2 |
| 8.BB.40 | Hentschelite | CuFe3+2(PO4)2(OH)2 |
| 8.BB.40 | Wilhelmkleinite | ZnFe3+2(AsO4)2(OH)2 |
| 8.BB.45 | Dokuchaevite | Cu8O2(VO4)3Cl3 |
| 8.BB.45 | Trolleite | Al4(PO4)3(OH)3 |
| 8.BB.45 | Yaroshevskite | Cu9O2(VO4)4Cl2 |
| 8.BB.50 | Namibite | Cu(BiO)2(VO4)(OH) |
| 8.BB.50 | Aleutite | [Cu5O2](AsO4)(VO4) · (Cu,K,Pb,Rb,Cs,)Cl |
| 8.BB.52a | Ericlaxmanite | Cu4O(AsO4)2 |
| 8.BB.52b | Kozyrevskite | Cu4O(AsO4)2 |
| 8.BB.55 | Phosphoellenbergerite | (Mg,◻)2Mg12(PO4,PO3OH)6(PO3OH,CO3)2(OH)6 |
| 8.BB.55 | Popovite | Cu5O2(AsO4)2 |
| 8.BB.60 | Urusovite | CuAl(AsO4)O |
| 8.BB.65 | Theoparacelsite | Cu3(As2O7)(OH)2 |
| 8.BB.70 | Turanite | Cu5(VO4)2(OH)4 |
| 8.BB.75 | Stoiberite | Cu5(VO4)2O2 |
| 8.BB.80 | Fingerite | Cu11(VO4)6O2 |
| 8.BB.85 | Averievite | Cu6(VO4)2O2Cl2 |
| 8.BB.90 | Richellite | CaFe3+2(PO4)2(OH,F)2 |
| 8.BB.90 | Lipscombite | Fe2+Fe3+2(PO4)2(OH)2 |
| 8.BB.90 | Zinclipscombite | ZnFe3+2(PO4)2(OH)2 |
Fluorescence of Zwieselite
Not fluorescent in UV.
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.
Internet Links for Zwieselite
mindat.org URL:
https://www.mindat.org/min-4436.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Zwieselite
Reference List:
Glocker, Ernst Friedrich (1847) Generum et specierum mineralium, secundum ordines naturales digestorum synopsis, omnium, quotquot adhuc reperta sunt, mineralium nomina complectens [A synopsis of the genera and species of minerals, according to their natural orders, including the names of all the minerals that have yet been discovered.]. Eduardus Anton. 348 pp. p.244
Fisher, D. Jerome (1957) Isokite and triplite from Bohemia. Mineralogical Magazine and Journal of the Mineralogical Society, 31 (238). 587-602 doi:10.1180/minmag.1957.031.238.05
Localities for Zwieselite
Showing 58 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and 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).
All localities listed without proper references should be considered as questionable.
Argentina | |
| Gay et al. (1994) |
| Colombo et al. (2018) |
Australia | |
| |
| Johnson (1956) |
| |
| Kampf et al. (2018) +2 other references |
| Lottermoser et al. (1997) +1 other reference |
| Eagle et al. (2015) |
| W. Birch 1996 AJM 2 (2) |
Brazil | |
| Coelho et al. (2025) |
Canada | |
| Dixon et al. (2014) |
Czech Republic | |
| Petr Pauliš (2000) +1 other reference |
| Staněk (1991) +4 other references |
| Novák et al. (2008) | |
| Staněk (1997) | |
| Škoda et al. (2007) +1 other reference |
Finland | |
| Pertti Hyvärinen collection |
France | |
| perso.wanadoo.fr (2004) |
| - (1998) | |
| - (1998) |
| - (1998) |
| perso.wanadoo.fr (2004) | |
| Guitard (2010) |
Germany | |
| Habel (2009) |
| Weiß (1990) |
| Weiß (1990) |
| Weiß (1990) |
| Fisher (1957) +1 other reference |
| Palache et al. (1951) +3 other references |
| Obermüller et al. (1993) | |
| Weiß (1990) |
| Fehr et al. (1985) |
| Dill et al. (2009) |
| Weiß (1990) +1 other reference |
| web.archive.org (2001) | |
| Kastning et al. (1996) +1 other reference | |
| Weiß (1990) |
| Weiß (1990) |
| DILL et al. (2009) | |
| Thomas et al. (2000) |
| Witzke (2024) |
| Zschäbitz et al. (2011) |
Namibia | |
| Keller et al. (1989) |
| Fransolet et al. (1986) |
Portugal | |
| Keck et al. (1998) |
| Schnorrer-Köhler et al. (1991) |
| Raade et al. (1993) +1 other reference | |
| Leal Gomes et al. (2009) |
| |
Romania | |
| HÎRTOPANU et al. (2025) |
Spain | |
| Roda-Robles et al. (2010) |
Sweden | |
| Smeds et al. (1998) |
| Smeds et al. (1998) |
| Swedish Museum of Natural History (Naturarv database) |
UK | |
| |
USA | |
| Eckel et al. (1997) |
| Gene Foord |
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Sítio do Castelo Mine, Folgosinho, Gouveia, Guarda, Portugal