Turkestanite
A valid IMA mineral species
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About Turkestanite
Formula:
(K,◻)(Ca,Na)2ThSi8O20 · nH2O
Colour:
Brown, apple-green
Lustre:
Vitreous, Dull
Hardness:
5½ - 6
Specific Gravity:
3.36
Crystal System:
Tetragonal
Member of:
Name:
Named after the discovery locality, along the Turkestan Ridge, Dara-i-Pioz massif, Tien-Shan Mountains, Tadjikistan.
Unique Identifiers
Mindat ID:
7345
Long-form identifier:
mindat:1:1:7345:1
IMA Classification of Turkestanite
Approved
IMA Formula:
(K,◻)(Ca,Na)2Th4+Si8O20·nH2O
Approval year:
1996
First published:
1997
Classification of Turkestanite
9.CH.10
9 : SILICATES (Germanates)
C : Cyclosilicates
H : [Si4O12]8- 4-membered double rings
9 : SILICATES (Germanates)
C : Cyclosilicates
H : [Si4O12]8- 4-membered double rings
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 |
|---|---|---|
| Tkt | 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 Turkestanite
Vitreous, Dull
Transparency:
Translucent
Colour:
Brown, apple-green
Hardness:
5½ - 6 on Mohs scale
Tenacity:
Brittle
Density:
3.36(2) g/cm3 (Measured) 3.39 g/cm3 (Calculated)
Optical Data of Turkestanite
Type:
Uniaxial (-)
RI values:
nω = 1.611 nε = 1.606
Max. Birefringence:
δ = 0.005
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:
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 uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Chemistry of Turkestanite
Mindat Formula:
(K,◻)(Ca,Na)2ThSi8O20 · nH2O
Element Weights:
Crystallography of Turkestanite
Crystal System:
Tetragonal
Class (H-M):
4/mmm(4/m2/m2/m) - Ditetragonal Dipyramidal
Space Group:
P4/mcc
Cell Parameters:
a = 7.592 Å, c = 14.824 Å
Ratio:
a:c = 1 : 1.953
Unit Cell V:
854.43 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Prisms. Forms observed include {100}, {001}, and rarely {101}.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0012357 | Turkestanite | Kabalov Yu K, Sokolova E V, Pautov L A, Schneider J (1998) Crystal structure of a new mineral turkestanite: a calcium analogue of steacyite Crystallography Reports 43 584-588 | 1998 | Dzhelisu massif, Alayskiy range, Tien Shan, Kyrgyzstan | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.40 Å | (100) |
| 5.31 Å | (70) |
| 3.33 Å | (65) |
| 2.654 Å | (59) |
| 5.36 Å | (40) |
| 2.175 Å | (25) |
| 7.59 Å | (23) |
Comments:
Dara-iPioz massif, Tajikistan. Data from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Type Occurrence of Turkestanite
Co-Type Localities:
General Appearance of Type Material:
At Dara-i-Pioz, occurs as prisms, 0.5 to 5 mm across, showing {100}, {001}, and rarely {101}. At the Jelisu massif, the mineral forms deformed {100} prisms, 2 to 50 mm across, rarely with {101} pyramids.
Place of Conservation of Type Material:
Museum of the Ilmen Reserve, Miass, Russia.
A. E. Fersman Mineralogical Museum, Moscow, Russia.
A. E. Fersman Mineralogical Museum, Moscow, Russia.
Geological Setting of Type Material:
Albitized Upper Carboniferous sandy shales in the contact aureole of the Jelisu massif (a massif consisting largely of albitized nepheline syenites). Also found in a boulder of microcline, pectolite, quartz, aegirine, and calcite near the alkaline to subalkaline intrusions of the Dara-i-Pioz massif.
Associated Minerals at Type Locality:
Synonyms of Turkestanite
Other Language Names for Turkestanite
Dutch:Turkestaniet
German:Turkestanit
Russian:Туркестанит
Simplified Chinese:突厥斯坦石
Spanish:Turkestanita
Traditional Chinese:突厥斯坦石
Relationship of Turkestanite to other Species
Member of:
Other Members of Steacyite Group:
| Arapovite | (K1-x◻x)(Ca,Na)2U4+Si8O20 (x ~ 0.5) | Tet. 4/mmm(4/m2/m2/m) : P4/mcc |
| Iraqite-(La) | KCa2(La,Ce,Th)Si8O20 | Tet. 4/mmm(4/m2/m2/m) : P4/mcc |
| Steacyite | K0.3(Na,Ca)2ThSi8O20 | Tet. 4/mmm(4/m2/m2/m) : P4/mcc |
Common Associates
Associations Based on Photo Data:
| 6 photos of Turkestanite associated with Aegirine | NaFe3+Si2O6 |
| 4 photos of Turkestanite associated with Quartz | SiO2 |
| 3 photos of Turkestanite associated with Eudialyte | Na15Ca6Fe3Zr3Si(Si25O73)(O,OH,H2O)3(Cl,OH)2 |
| 2 photos of Turkestanite associated with Steacyite | K0.3(Na,Ca)2ThSi8O20 |
| 1 photo of Turkestanite associated with Albite | Na(AlSi3O8) |
| 1 photo of Turkestanite associated with Calcite | CaCO3 |
| 1 photo of Turkestanite associated with Fluorite | CaF2 |
| 1 photo of Turkestanite associated with Arapovite | (K1-x◻x)(Ca,Na)2U4+Si8O20 (x ~ 0.5) |
Related Minerals - Strunz-mindat Grouping
| 9.CH.05 | Khvorovite | (Pb,Ba,K)4Ca2[Si8B2(Si,B)2O28]F |
| 9.CH.05 | Guastoniite-(Y) | Pb4(YCa)(Si8B4O28)F |
| 9.CH.05 | Kapitsaite-(Y) | (Ba,K,Pb)4(Y,Ca)2Si8(B,Si)4O28F |
| 9.CH.05 | Hyalotekite | (Ba,Pb,K)4(Ca,Y)2(B,Be)2(Si,B)2Si8O28(F,Cl) |
| 9.CH.05 | Itsiite | Ba4Ca2[Si8B4O28]◻ |
| 9.CH.10 | Arapovite | (K1-x◻x)(Ca,Na)2U4+Si8O20 (x ~ 0.5) |
| 9.CH.10 | Steacyite | K0.3(Na,Ca)2ThSi8O20 |
| 9.CH.10 | Iraqite-(La) | KCa2(La,Ce,Th)Si8O20 |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 25.3877% | 1,015,508 | α, β, γ |
| Potassium (K) | 4.2778% | 1,326 | β, γ |
For comparison:
- Banana: ~15 Bq per fruit
- Granite: 1,000–3,000 Bq/kg
- EU exemption limit: 10,000 Bq/kg
Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.
Interactive Simulator:
Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!
Activity: –
| Distance | Dose rate | Risk |
|---|---|---|
| 1 cm | ||
| 10 cm | ||
| 1 m |
The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).
D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield
Other Information
IR Spectrum:
The infrared spectrum has strong absorption bands at 449, 591, 1040, and 1097 cm-1, typical for ring silicates, and also a broad band at about 3460 cm-1 attributable to H2O.
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 Turkestanite
mindat.org URL:
https://www.mindat.org/min-7345.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Turkestanite
Reference List:
Pautov, L. A., Agakhanov, A. A., Sokolova, E. V., Kabalov, Y. K. (1997) Turkestanite Th(Ca,Na)2(K1-x◻x)Si8O20·nH2O – a new mineral. Zapiski Vserossijskogo Mineralogicheskogo Obshchestva, 126 (6) 45-55
Jambor, John L., Grew, Edward S., Roberts, Andrew C. (1998) New mineral names. American Mineralogist, 83 (11) 1347-1352
Vilalva, F. C. J., Vlach, S. R. F. (2010) Major- and trace-element composition of REE-rich turkestanite from peralkaline granites of the Morro Redondo Complex, Graciosa Province, south Brazil. Mineralogical Magazine, 74 (4) 645-658 doi:10.1180/minmag.2010.074.4.645
Localities for Turkestanite
Showing 15 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.
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Dara-i-Pioz Massif, Districts of Republican Subordination, Tajikistan