Tokkoite
A valid IMA mineral species
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About Tokkoite
Formula:
K2Ca4[Si7O18(OH)](OH,F)
Previous formula: K2Ca4Si7O17(O,OH,F)4
Colour:
Light brown, light yellow, colorless
Lustre:
Vitreous
Hardness:
4 - 5
Specific Gravity:
2.76
Crystal System:
Triclinic
Name:
Named after its discovery locality, Davan stream near Vislopolovka village, between the Chara and Tokko Rivers, Saha Republic, Russia.
Type Locality:
Isostructural with:
Chemically similar to mountainite, hydroxyapophyllite-(K), shlykovite, rhodesite, and cryptophyllite.
The difference from tinaksite is in (1) greater lattice constants (mainly the parameter b), (2) longer distances, (3) longer M1-M3 and O20-O2 bonds, and (4) more distorted M1 polyhedron. Contains significant admixture of Fe3+. Material from Patyn Mt. massif is nearly pure end member.
The difference from tinaksite is in (1) greater lattice constants (mainly the parameter b), (2) longer distances, (3) longer M1-M3 and O20-O2 bonds, and (4) more distorted M1 polyhedron. Contains significant admixture of Fe3+. Material from Patyn Mt. massif is nearly pure end member.
Unique Identifiers
Mindat ID:
3989
Long-form identifier:
mindat:1:1:3989:1
Similar Names
| Tokyoite | A valid IMA mineral species | Ba2Mn3+(VO4)2(OH) |
IMA Classification of Tokkoite
Approved
IMA Formula:
K2Ca4Si7O18(OH)F
Approval year:
1985
First published:
1986
Classification of Tokkoite
9.DG.75
9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
67.2.1.2
67 : INOSILICATES Unbranched Chains with W > 2
2 : Unbranched Chains with W>2 with W=5
67 : INOSILICATES Unbranched Chains with W > 2
2 : Unbranched Chains with W>2 with W=5
14.6.5
14 : Silicates not Containing Aluminum
6 : Silicates of Ca with alkali or Mg or both
14 : Silicates not Containing Aluminum
6 : Silicates of Ca with alkali or Mg or both
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 |
|---|---|---|
| Tok | 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 Tokkoite
Vitreous
Transparency:
Transparent
Colour:
Light brown, light yellow, colorless
Streak:
White
Hardness:
4 - 5 on Mohs scale
Cleavage:
Perfect
Perfect on {010} and good on {110}
Perfect on {010} and good on {110}
Fracture:
Splintery
Density:
2.76(1) g/cm3 (Measured) 2.77 g/cm3 (Calculated)
Optical Data of Tokkoite
Type:
Biaxial (+)
RI values:
nα = 1.57 nγ = 1.577
2V:
Measured: 38°
Max. Birefringence:
δ = 0.007
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
Chemistry of Tokkoite
Mindat Formula:
K2Ca4[Si7O18(OH)](OH,F)
Previous formula: K2Ca4Si7O17(O,OH,F)4
Previous formula: K2Ca4Si7O17(O,OH,F)4
Element Weights:
Common Impurities:
Ti,Fe,Mn,Mg,Na,H2O
Crystallography of Tokkoite
Crystal System:
Triclinic
Cell Parameters:
a = 10.43 Å, b = 12.51 Å, c = 7.11 Å
α = 89.92°, β = 99.75°, γ = 92.89°
α = 89.92°, β = 99.75°, γ = 92.89°
Ratio:
a:b:c = 0.834 : 1 : 0.568
Unit Cell V:
913.12 ų (Calculated from Unit Cell)
Comment:
mean parameters concerning the structure refinement (Lacalamita et al., 2016): a~10.423, b~12.477, c~7.112, α~89.92, β~99.68, γ~92.97, V~910.5
Crystal Structure
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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) |
|---|---|---|---|---|---|---|---|
| 0010996 | Tokkoite | Rozhdestvenskaya I V, Nikishova L V, Lazebnik Yu D, Lazebnik K A (1989) The crystal structure of tokkoite and its relation to the structure of tinaksite Zeitschrift fur Kristallographie 189 195-204 |  | 1989 | Murun massif, southwestern Yakutia, Russia | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.34 Å | (55) |
| 3.32 Å | (85) |
| 3.15 Å | (100) |
| 3.125 Å | (85) |
| 3.075 Å | (62) |
| 3.044 Å | (91b) |
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 Tokkoite
General Appearance of Type Material:
Radiating or columnar aggregates.
Place of Conservation of Type Material:
1) Institute of Geology and Geophysics, Siberian Division, Academy of Sciences, Novosibirsk, Russia.
2) Geological Museum, Yakutsk Scientific Center, Academy of Sciences, Yakutsk, Russia.
2) Geological Museum, Yakutsk Scientific Center, Academy of Sciences, Yakutsk, Russia.
Geological Setting of Type Material:
Alkaline massif. Occurs in zones a few centimeters thick or in streaky, elongated, nearly monomineralic segregations.
Associated Minerals at Type Locality:
Synonyms of Tokkoite
Other Language Names for Tokkoite
Common Associates
Associations Based on Photo Data:
| 13 photos of Tokkoite associated with Charoite | (K,Sr)15-16(Ca,Na)32[Si6O11(O,OH)6]2[Si12O18(O,OH)12]2[Si17O25(O,OH)18]2(OH,F)4 · ~3H2O |
| 9 photos of Tokkoite associated with Frankamenite | K3Na3Ca5(Si12O30)(F,OH)4 · H2O |
| 7 photos of Tokkoite associated with Aegirine | NaFe3+Si2O6 |
| 5 photos of Tokkoite associated with 'Lavrovite' | (Ca,Na)(Mg,V3+)Si2O6 |
| 5 photos of Tokkoite associated with Patynite | NaKCa4[Si9O23] |
| 3 photos of Tokkoite associated with Diopside | CaMgSi2O6 |
| 3 photos of Tokkoite associated with Graphite | C |
Related Minerals - Strunz-mindat Grouping
| 9.DG. | Barrydawsonite-(Y) | Na1.5Y0.5CaSi3O8(OH) |
| 9.DG. | Paratobermorite | Ca5AlSi5O16(OH) · 5H2O |
| 9.DG. | Calcinaksite | KNaCa(Si4O10) · H2O |
| 9.DG. | Alvesite | NaKZrSi6O15 · 2H2O |
| 9.DG.02 | Steedeite | NaMn2[Si3BO9](OH)2 |
| 9.DG.02 | Nolzeite | NaMn2[Si3BO9](OH)2 · 2H2O |
| 9.DG.05 | Murakamiite | LiCa2Si3O8(OH) |
| 9.DG.05 | Serandite | NaMn2+2Si3O8(OH) |
| 9.DG.05 | Bustamite | CaMn2+(Si2O6) |
| 9.DG.05 | Pectolite | NaCa2Si3O8(OH) |
| 9.DG.05 | Tanohataite | LiMn2Si3O8(OH) |
| 9.DG.05 | Dalnegorskite | Ca5Mn2+(Si3O9)2 |
| 9.DG.05 | 'Wollastonite-1A' | CaSiO3 |
| 9.DG.05 | Wollastonite | Ca3(Si3O9) |
| 9.DG.05 | Ferrobustamite | CaFe2+(Si2O6) |
| 9.DG.05 | Schizolite | NaCaMnSi3O8(OH) |
| 9.DG.07 | Cascandite | CaScSi3O8(OH) |
| 9.DG.08 | Plombièrite | Ca5Si6O16(OH)2 · 7H2O |
| 9.DG.10 | Clinotobermorite | Ca5Si6O17 · 5H2O |
| 9.DG.10 | Riversideite | Ca5Si6O16(OH)2 · 2H2O |
| 9.DG.10 | Tobermorite | Ca5Si6O17 · 5H2O |
| 9.DG.12 | Jusite | Na2Ca15Al4Si16O54 · 17H2O |
| 9.DG.12 | Kenotobermorite | Ca4Si6O15(OH)2 · 5H2O |
| 9.DG.15 | Foshagite | Ca4(Si3O9)(OH)2 |
| 9.DG.20 | Jennite | Ca9(Si3O9)2(OH)8 · 8H2O |
| 9.DG.20 | Kamenevite | K2TiSi3O9 · H2O |
| 9.DG.25 | Paraumbite | K3Zr2H(Si3O9)2 · nH2O |
| 9.DG.25 | Umbite | K2(Zr,Ti)Si3O9 · H2O |
| 9.DG.30 | Sørensenite | Na4SnBe2Si6O16(OH)4 |
| 9.DG.32 | Escheite | Ca2NaMnTi5[Si12O34]O2(OH)3 · 12H2O |
| 9.DG.35 | Xonotlite | Ca6(Si6O17)(OH)2 |
| 9.DG.40 | Hillebrandite | Ca2(SiO3)(OH)2 |
| 9.DG.45 | Zorite | Na8(Ti,Nb)5(Si6O17)2(OH,O)5 · 14H2O |
| 9.DG.45 | Chivruaiite | Ca4(Ti,Nb)5(Si6O17)2(OH,O)5 · 13-14H2O |
| 9.DG.50 | Haineaultite | (Na,Ca)5Ca(Ti,Nb)5(Si6O17)2(OH,F)8 · 5H2O |
| 9.DG.55 | Epididymite | Na2Be2Si6O15 · H2O |
| 9.DG.60 | Eudidymite | Na2Be2Si6O15 · H2O |
| 9.DG.65 | Elpidite | Na2ZrSi6O15 · 3H2O |
| 9.DG.65 | Patynite | NaKCa4[Si9O23] |
| 9.DG.67 | Whelanite | Cu2+2Ca6[Si6O17(OH)](CO3)(OH)3 · 2H2O |
| 9.DG.70 | Enricofrancoite | KNaCaSi4O10 |
| 9.DG.70 | Yusupovite | Na2Zr(Si6O15) · 2.5H2O |
| 9.DG.70 | Litidionite | KNaCuSi4O10 |
| 9.DG.70 | Fenaksite | (K,Na)4(Fe,Mn)2(Si4O10)2(OH,F) |
| 9.DG.70 | Manaksite | KNaMnSi4O10 |
| 9.DG.75 | Senkevichite | CsKNaCa2TiO[Si7O18](OH) |
| 9.DG.75 | Tinaksite | K2Na(Ca,Mn2+)2TiO[Si7O18(OH)] |
| 9.DG.80 | Fluorcanasite | K3Na3Ca5Si12O30F4 · H2O |
| 9.DG.80 | Canasite | K3Na3Ca5Si12O30(OH)4 |
| 9.DG.85 | Miserite | K1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2O |
| 9.DG.90 | Frankamenite | K3Na3Ca5(Si12O30)(F,OH)4 · H2O |
| 9.DG.92 | Charoite | (K,Sr)15-16(Ca,Na)32[Si6O11(O,OH)6]2[Si12O18(O,OH)12]2[Si17O25(O,OH)18]2(OH,F)4 · ~3H2O |
| 9.DG.95 | Yuksporite | K4(Ca,Na)14(Sr,Ba)2(◻,Mn,Fe)(Ti,Nb)4(O,OH)4(Si6O17)2(Si2O7)3(H2O,OH)3 |
| 9.DG.97 | Eveslogite | (Na,K,Ca,Sr,Ba)48 [(Ti,Nb,Mn,Fe2+)12Si48O144(OH)12](F,OH,Cl)14 |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 10.3283% | 3,202 | 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
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 Tokkoite
mindat.org URL:
https://www.mindat.org/min-3989.html
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References for Tokkoite
Reference List:
Hawthorne, Frank C., Burke, Ernst A. J., Ercit, T. Scott, Grew, Edward S., Grice, Joel D., Jambor, John L., Puziewicz, Jacek, Roberts, Andrew C., Vanko, David A. (1988) New Mineral Names. American Mineralogist, 73 (1-2) 189-199
Rozhdestvenskaya, I. V.; Nikishova, L. V.; Lazebnik, Yu. D.; Lazebnik, K. A. (1989) The crystal structure of tokkoite and its relation to the structure of tinaksite. Zeitschrift für Kristallographie, 189 (3-4). 195-204 doi:10.1524/zkri.1989.189.3-4.195
Localities for Tokkoite
Showing 4 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.
Russia | |
| www.mindat.org (n.d.) +5 other references |
| Dokuchits et al. (2022) | |
| Pekov (1998) |
| Pavel M. Kartashov (n.d.) +1 other reference |
Quick NavTopAbout TokkoiteUnique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatRadioactivityOther InformationInternet Links References Localities Locality List
Murunskii Massif, Chara and Tokko Rivers Confluence, Aldan Shield, Russia