Isokite
A valid IMA mineral species - grandfathered
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About Isokite
Formula:
CaMg(PO4)F
Colour:
white, buff, pale pink
Lustre:
Silky, Pearly
Hardness:
4½ - 5
Specific Gravity:
3.15 - 3.27
Crystal System:
Monoclinic
Member of:
Name:
Named for the community of Isoka, Zambia, about 24 kilometers west of the type locality.
Tilasite Group; the F-analogue of panasqueiraite.
Isokite-tilasite series is known from the Tolbachik volcano.
Isokite-tilasite series is known from the Tolbachik volcano.
Unique Identifiers
Mindat ID:
2054
Long-form identifier:
mindat:1:1:2054:7
Similar Names
| Isovite | A valid IMA mineral species | (Cr,Fe)23C6 |
IMA Classification of Isokite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
CaMgPO4F
First published:
1955
Classification of Isokite
8.BH.10
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
H : With medium-sized and large cations, (OH,etc.):RO4 = 1:1
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
H : With medium-sized and large cations, (OH,etc.):RO4 = 1:1
41.5.6.2
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
5 : (AB)2(XO4)Zq
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
5 : (AB)2(XO4)Zq
22.1.11
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 |
|---|---|---|
| Iso | 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 Isokite
Silky, Pearly
Transparency:
Translucent
Colour:
White, buff, pale pink
Hardness:
4½ - 5 on Mohs scale
Tenacity:
Brittle
Cleavage:
Very Good
{010}
{010}
Density:
3.15 - 3.27 g/cm3 (Measured) 3.29 g/cm3 (Calculated)
Optical Data of Isokite
Type:
Biaxial (+)
RI values:
nα = 1.59 nβ = 1.595 nγ = 1.615
2V:
Measured: 51°
Max. Birefringence:
δ = 0.025
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:
Moderate (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 distinct
Chemistry of Isokite
Mindat Formula:
CaMg(PO4)F
Element Weights:
Crystallography of Isokite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Cell Parameters:
a = 6.52 Å, b = 8.75 Å, c = 7.51 Å
β = 121.47°
β = 121.47°
Ratio:
a:b:c = 0.745 : 1 : 0.858
Unit Cell V:
365.43 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals are flattened on {010}, elongated along {100}.
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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CIF File Best | x | y | z | a | b | c
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Rotation
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Labels
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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) |
|---|---|---|---|---|---|---|---|
| 0010337 | Isokite | Yang H, Zwick J, Downs R T, Costin G (2007) Isokite, CaMg(PO4)F0.8(OH)0.2, isomorphous with titanite Acta Crystallographica C63 i89-i90 |  | 2007 | Kjorrestad, near Bamle, Norway | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.185 Å | (vvs) |
| 3.023 Å | (vvs) |
| 2.784 Å | (m) |
| 2.630 Å | (vvs) |
| 2.586 Å | (m) |
| 2.301 Å | (s) |
| 1.720 Å | (s) |
Reference:
Comments:
Nkombwa Hill, Zambia
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites | |
| 36 : Carbonatites, kimberlites, and related igneous rocks | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47c : [Carbonates, phosphates, borates, nitrates] | |
| 47g : [Halogen-bearing surface weathering minerals] |
Type Occurrence of Isokite
General Appearance of Type Material:
Spherulites and radiating aggregates of thin plates to a couple millimeters in diameter.
Place of Conservation of Type Material:
Natural History Museum, London, England
Geological Setting of Type Material:
Carbonatite
Other Language Names for Isokite
Relationship of Isokite to other Species
Member of:
Other Members of Tilasite Group:
| Arsenatrotitanite | NaTi(AsO4)O | Mon. 2/m : B2/b |
| Durangite | NaAl(AsO4)F | Mon. 2/m : B2/b |
| Kononovite | NaMg(SO4)F | Mon. 2/m : B2/b |
| Lacroixite | NaAl(PO4)F | Mon. 2/m : B2/b |
| Maxwellite | NaFe3+(AsO4)F | Mon. 2/m : P2/m |
| Panasqueiraite | CaMg(PO4)(OH) | Mon. |
| Reznitskyite | CaMg(VO4)F | Mon. 2/m : B2/b |
| Tilasite | CaMg(AsO4)F | Mon. |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 4 photos of Isokite associated with Strengite | FePO4 · 2H2O |
| 3 photos of Isokite associated with Wagnerite | Mg2(PO4)F |
| 2 photos of Isokite associated with Triplite | Mn2+2(PO4)F |
| 1 photo of Isokite associated with Rutile | TiO2 |
| 1 photo of Isokite associated with Phosphosiderite | FePO4 · 2H2O |
| 1 photo of Isokite associated with Plimerite | ZnFe3+4(PO4)3(OH)5 |
| 1 photo of Isokite associated with Lun'okite | (Mn,Ca)(Mg,Fe,Mn)Al(PO4)2OH · 4H2O |
Related Minerals - Strunz-mindat Grouping
| 8.BH. | Peterchinite | Zn3Zn2(OH)6As[O3(OH)3] |
| 8.BH. | Reznitskyite | CaMg(VO4)F |
| 8.BH. | Plumbogottlobite | PbMg(VO4)(OH) |
| 8.BH. | Cuprozheshengite | Pb4CuZn2(AsO4)2(PO4)2(OH)2 |
| 8.BH. | Zheshengite | Pb4ZnZn2(AsO4)2(PO4)2(OH)2 |
| 8.BH. | Crimsonite | PbFe3+2(PO4)2(OH)2 |
| 8.BH.05 | Thadeuite | Ca(Mg,Fe2+)3(PO4)2(OH,F)2 |
| 8.BH.10 | Panasqueiraite | CaMg(PO4)(OH) |
| 8.BH.10 | Lacroixite | NaAl(PO4)F |
| 8.BH.10 | Arsenatrotitanite | NaTi(AsO4)O |
| 8.BH.10 | Maxwellite | NaFe3+(AsO4)F |
| 8.BH.10 | Durangite | NaAl(AsO4)F |
| 8.BH.10 | Kononovite | NaMg(SO4)F |
| 8.BH.15 | Drugmanite | Pb2Fe3+(PO4)(PO3OH)(OH)2 |
| 8.BH.20 | Nigelcookite | PbFe2+2V3+2(PO4)3(OH)3 |
| 8.BH.20 | Plumbojohntomaite | PbFe2+2Fe3+2(PO4)3(OH)3 |
| 8.BH.20 | Cirrolite | Ca3Al2(PO4)3(OH)3 (?) |
| 8.BH.20 | Penikisite | Ba(Mg,Fe2+,Ca)2Al2(PO4)3(OH)3 |
| 8.BH.20 | Perloffite | Ba(Mn2+,Fe2+)2Fe3+2(PO4)3(OH)3 |
| 8.BH.20 | Bjarebyite Group | |
| 8.BH.20 | Strontioperloffite | SrMn2+2Fe3+2(PO4)3(OH)3 |
| 8.BH.20 | Plumboperloffite | PbMn2+2Fe3+2(PO4)3(OH)3 |
| 8.BH.20 | Johntomaite | BaFe2+2Fe3+2(PO4)3(OH)3 |
| 8.BH.20 | Bjarebyite | (Ba,Sr)(Mn2+,Fe2+,Mg)2Al2(PO4)3(OH)3 |
| 8.BH.20 | Kulanite | Ba(Fe2+,Mn2+,Mg)2(Al,Fe3+)2(PO4)3(OH)3 |
| 8.BH.25 | Bertossaite | Li2CaAl4(PO4)4(OH)4 |
| 8.BH.25 | Natropalermoite | Na2SrAl4(PO4)4(OH)4 |
| 8.BH.25 | Palermoite | Li2SrAl4(PO4)4(OH)4 |
| 8.BH.30 | Sewardite | CaFe3+2(AsO4)2(OH)2 |
| 8.BH.30 | Carminite | PbFe3+2(AsO4)2(OH)2 |
| 8.BH.35 | Adelite | CaMg(AsO4)(OH) |
| 8.BH.35 | Duftite | PbCu(AsO4)(OH) |
| 8.BH.35 | Cobaltaustinite | CaCo(AsO4)(OH) |
| 8.BH.35 | Nickelaustinite | CaNi(AsO4)(OH) |
| 8.BH.35 | Gabrielsonite | PbFe3+(As3+O3)O |
| 8.BH.35 | Conichalcite | CaCu(AsO4)(OH) |
| 8.BH.35 | Arsendescloizite | PbZn(AsO4)(OH) |
| 8.BH.35 | 'Duftite-alpha' | PbCu(AsO4)(OH) |
| 8.BH.35 | Gottlobite | CaMg(VO4)(OH) |
| 8.BH.35 | Austinite | CaZn(AsO4)(OH) |
| 8.BH.35 | Hermannroseite | CaCu(PO4)(OH) |
| 8.BH.35 | Tangeite | CaCu(VO4)(OH) |
| 8.BH.40 | Čechite | PbFe2+(VO4)(OH) |
| 8.BH.40 | Khorixasite | (Bi0.67◻0.33)Cu(VO4)(OH) |
| 8.BH.40 | Mottramite | PbCu(VO4)(OH) |
| 8.BH.40 | Descloizite | PbZn(VO4)(OH) |
| 8.BH.40 | Pyrobelonite | PbMn2+(VO4)(OH) |
| 8.BH.45 | Bayldonite | PbCu3(AsO4)2(OH)2 |
| 8.BH.45 | Vésigniéite | BaCu3(VO4)2(OH)2 |
| 8.BH.50 | Paganoite | NiBi(AsO4)O |
| 8.BH.55 | Jagowerite | BaAl2(PO4)2(OH)2 |
| 8.BH.55 | Harrisonite | Ca(Fe2+,Mg)6(PO4)2(SiO4)2 |
| 8.BH.60 | Attakolite | CaMn2+Al4(SiO3OH)(PO4)3(OH)4 |
| 8.BH.65 | Leningradite | PbCu3(VO4)2Cl |
| 8.BH.70 | Katiarsite | KTiO(AsO4) |
| 8.BH.70 | Yurgensonite | K2SnTiO2(AsO4)2 |
| 8.BH.75 | Melanarsite | K3Cu7Fe3+O4(AsO4)4 |
| 8.BH.80 | Evseevite | Na2Mg(AsO4)F |
| 8.BH.80 | Moraskoite | Na2Mg(PO4)F |
| 8.BH.85 | Piccoliite | NaCaMn3+2(AsO4)2O(OH) |
Fluorescence of Isokite
Fluoresces blue under short wave 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 Isokite
mindat.org URL:
https://www.mindat.org/min-2054.html
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References for Isokite
Reference List:
Deans, T., McConnell, J. D. C., Pickup, R. (1955) Isokite, CaMgPO4F, a new mineral from Northern Rhodesia. Mineralogical Magazine and Journal of the Mineralogical Society, 30 (230) 681-690 doi:10.1180/minmag.1955.030.230.01
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
Jaffe, Howard W., Hall, Leo M., Evans, Howard T. (1992) Wagnerite with isokite from the Benson Mines, west-central Adirondack Highlands, New York. Mineralogical Magazine, 56 (383) 227-233 doi:10.1180/minmag.1992.056.383.09
Hochleitner, Rupert, Fehr, Karl Thomas (2005) Isokite, CaMg[FIPO4], from Senhora de Assunção, Portugal: new find and new data. Neues Jahrbuch für Mineralogie - Abhandlungen, 182 (1). 103-108 doi:10.1127/0077-7757/2005/0035
Ercit, T. S.; Piilonen, P.C.; Locock, A.J.; Kolitsch, U.; Rowe, R. (2006) New mineral names. American Mineralogist, 91 (7). 1201-1209 doi:10.2138/am.2006.467
Yang, Hexiong, Zwick, Justin, Downs, Robert T., Costin, Gelu (2007) Isokite, CaMg(PO4)F0.8(OH)0.2, isomorphous with titanite. Acta Crystallographica Section C Crystal Structure Communications, 63 (10) 189-190 doi:10.1107/s0108270107041169
Localities for Isokite
Showing 25 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.
Australia | |
| Bottrill +1 other reference |
Austria | |
| Strasser (1989) |
| Strasser (1989) | |
| Strasser (1989) |
Brazil | |
| Menezes (n.d.) |
| Silva et al. (2019) |
| Orris et al. (2002) +2 other references |
Czech Republic | |
| |
| Sejkora et al. (2006) +1 other reference |
Germany | |
| Thomas et al. (2000) |
Norway | |
| Analyzed by PXRD by Alf Olav Larsen |
| RRUFF ID R050519.2 and RRUFF ID: ... +1 other reference | |
| Neumann (1985) |
Portugal | |
| |
| Alves et al. (2012) |
| Isaac's et al +7 other references | |
| Leal Gomes et al. (2009) |
| |
| Correia Neves (1962) |
| Hochleitner et al. (2005) |
Spain | |
| www.foro-minerales.com (n.d.) |
| Gonzalez del Tánago (1985) |
USA | |
| NY State Museum spec. no. 19101 |
| Jaffe et al. (1992) |
Zambia (TL) | |
| Deans et al. (1955) +1 other reference |
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Assunção Mine, Aldeia Nova, Ferreira de Aves, Sátão, Viseu, Portugal