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Tokkoite

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Formula:
K2Ca4[Si7O18(OH)](OH,F)
Previous formula: K2Ca4Si7O17(O,OH,F)4
Colour:
Light yellow
Lustre:
Vitreous
Hardness:
4 - 5
Crystal System:
Triclinic
Name:
Named after its discovery locality, Davan stream near Vislopolovka village, between the Chara and Tokko Rivers, Saha Republic, Russia.
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+.


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Classification of TokkoiteHide

Approved
Approval Year:
1985
9.DG.75

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
14.6.5

14 : Silicates not Containing Aluminum
6 : Silicates of Ca with alkali or Mg or both

Physical Properties of TokkoiteHide

Vitreous
Transparency:
Transparent
Colour:
Light yellow
Hardness:
4 - 5 on Mohs scale

Optical Data of TokkoiteHide

Type:
Biaxial (+)
RI values:
nα = 1.570 nγ = 1.577
2V:
Measured: 38°
Max Birefringence:
δ = 0.007
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r > v

Chemical Properties of TokkoiteHide

Formula:
K2Ca4[Si7O18(OH)](OH,F)

Previous formula: K2Ca4Si7O17(O,OH,F)4
IMA Formula:
K2Ca4Si7O18(OH)F
Common Impurities:
Ti,Fe,Mn,Mg,Na,H2O

Crystallography of TokkoiteHide

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°
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

Type Occurrence of TokkoiteHide

Synonyms of TokkoiteHide

Other Language Names for TokkoiteHide

German:Tokkoit
Spanish:Tokkoita

Common AssociatesHide

Associated Minerals Based on Photo Data:
Charoite7 photos of Tokkoite associated with Charoite on mindat.org.
Aegirine5 photos of Tokkoite associated with Aegirine on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.DG.05BustamiteCaMn2+(Si2O6)Tric. 1 : P1
9.DG.05FerrobustamiteCaFe2+(Si2O6)Tric.
9.DG.05PectoliteNaCa2Si3O8(OH)Tric. 1 : P1
9.DG.05SeranditeNaMn2+2Si3O8(OH)Tric. 1 : P1
9.DG.05WollastoniteCaSiO3Tric. 1 : P1
9.DG.05Wollastonite-1ACaSiO3Tric.
9.DG.07CascanditeCa(Sc,Fe3+)(HSi3O9)Tric.
9.DG.08Plombièrite[Ca4Si6O16(OH)2 · 2H2O]·(Ca·5H2O)Orth.
9.DG.10Clinotobermorite[Ca4Si6O17 · 2H2O]·(Ca·3H2O)Mon.
9.DG.10RiversideiteCa5(HSi3O9)2 · 2H2OOrth.
9.DG.10Tobermorite[Ca4Si6O17 · 2H2O]·(Ca·3H2O)Orth.
9.DG.15FoshagiteCa4(Si3O9)(OH)2Tric.
9.DG.20JenniteCa9(Si3O9)2(OH)8 · 8H2OTric.
9.DG.25ParaumbiteK3Zr2H(Si3O9)2 · nH2OOrth.
9.DG.25UmbiteK2(Zr,Ti)Si3O9 · H2OOrth.
9.DG.30SørenseniteNa4SnBe2Si6O16(OH)4Mon. 2/m : B2/b
9.DG.35XonotliteCa6(Si6O17)(OH)2Mon. 2/m
9.DG.40HillebranditeCa2(SiO3)(OH)2Orth. mmm (2/m 2/m 2/m) : Cmcm
9.DG.45ZoriteNa8(Ti,Nb)5(Si6O17)2(OH,O)5 · 14H2OOrth.
9.DG.45ChivruaiiteCa4(Ti,Nb)5(Si6O17)2(OH,O)5 · 13-14H2OOrth. mmm (2/m 2/m 2/m) : Cmmm
9.DG.50Haineaultite(Na,Ca)5Ca(Ti,Nb)5(Si6O17)2(OH,F)8 · 5H2OOrth. 2 2 2 : C2 2 2
9.DG.55EpididymiteNa2Be2Si6O15 · H2OOrth. mmm (2/m 2/m 2/m) : Pnma
9.DG.60EudidymiteNa2Be2Si6O15 · H2OMon. 2/m : B2/b
9.DG.65ElpiditeNa2ZrSi6O15 · 3H2OOrth.
9.DG.70Fenaksite(K,Na)4(Fe,Mn)2(Si4O10)2(OH,F)Tric.
9.DG.70LitidioniteCuNaKSi4O10Tric.
9.DG.70ManaksiteKNaMnSi4O10Tric.
9.DG.75TinaksiteK2Na(Ca,Mn2+)2Ti[O|Si7O18(OH)]Tric.
9.DG.75SenkevichiteCsKNaCa2Ti[O|Si7O18(OH)]Tric. 1 : P1
9.DG.80CanasiteK3Na3Ca5Si12O30(OH)4
9.DG.80FluorcanasiteK3Na3Ca5Si12O30F4 · H2OMon. m : Bm
9.DG.85MiseriteK1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2OTric.
9.DG.90FrankameniteK3Na3Ca5(Si12O30)(F,OH)4 · H2OTric.
9.DG.92Charoite(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 · ~3H2OMon. 2/m : P21/m
9.DG.95YuksporiteK4(Ca,Na)14(Sr,Ba)2(◻,Mn,Fe)(Ti,Nb)4(O,OH)4(Si6O17)2(Si2O7)3(H2O,OH)3Orth.
9.DG.97Eveslogite(Na,K,Ca,Sr,Ba)48 [(Ti,Nb,Mn,Fe2+)12Si48O144(OH)12](F,OH,Cl)14Mon. 2/m : P2/m

Related Minerals - Dana Grouping (8th Ed.)Hide

67.2.1.1TinaksiteK2Na(Ca,Mn2+)2Ti[O|Si7O18(OH)]Tric.

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

14.6.1CombeiteNa2Ca2(Si6O18)0.5Trig. 3m (3 2/m) : R3m
14.6.2PectoliteNaCa2Si3O8(OH)Tric. 1 : P1
14.6.3Pectolite-M2abcNaCa2[HSi3O9]
14.6.4DenisoviteCa2(K,Na)Si3O8(F,OH)2Mon.
14.6.6MountainiteKNa2Ca2[Si8O19(OH)] · 6H2OMon. 2/m : P2/b
14.6.7RhodesiteKHCa2Si8O19 · 5H2OOrth. mmm (2/m 2/m 2/m)
14.6.8MiseriteK1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2OTric.
14.6.9ÅkermaniteCa2Mg(Si2O7)Tet. 4 2m : P4 21m
14.6.10MonticelliteCaMgSiO4Orth.
14.6.11MerwiniteCa3Mg(SiO4)2Mon. 2/m : P21/b
14.6.12DiopsideCaMgSi2O6Mon. 2/m : B2/b
14.6.13Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2Mon. 2/m : B2/m

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for TokkoiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Mineralogicheskii Zhurnal, Kiev (1986): 8(3): 85-89.
American Mineralogist (1988): 73: 196.
Zeitschrift für Kristallographie: 189: 195-204.
Lacalamita, M., Mesto, E., Kaneva, E., Scordari, F., Pedrazzi, G., Vladkyn, N., Schingaro, E. (2016): Structure refinement and crystal chemistry of tokkoite and tinaksite from Murun massif (Russia). Mineralogical Magazine: 80 (in press); http://forum.amiminerals.it/viewtopic.php?f=5&t=12645 (2016)

Internet Links for TokkoiteHide

Localities for TokkoiteHide

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Russia (TL)
 
  • Eastern-Siberian Region
    • Sakha Republic (Saha Republic; Yakutia)
      • Aldan Shield
        • Chara and Tokko Rivers Confluence
          • Murunskii Massif
            • Sirenevyi Kamen' Deposit
Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
Mineral and/or Locality  
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