Tokkoite Mineral Data

Tokkoite Mineral Data +

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General Tokkoite Information

Chemical Formula:

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

Composition:

Molecular Weight = 758.60 gm

Potassium 10.31 % K 12.42 % K₂O

Calcium 21.13 % Ca 29.57 % CaO

Silicon 25.92 % Si 55.44 % SiO₂

Hydrogen 0.17 % H 1.48 % H₂O

Oxygen 40.60 % O

Fluorine 1.88 % F 1.88 % F

- % F -0.79 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

K₂Ca₄Si₇O₁₈(OH)_1.25F_0.75

IMA Status:

Approved IMA 1986

Locality:

Murun massif, between the Charo and Tokko rivers, Yakutia, Russia. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Synonym:

ICSD 67211

PDF 40-517

Tokkoite Image

Images:

Tokkoite Charoite

Comments: Yellow crystalline tokkoite intermixed with purple charoite (viewed cross-sectional to fiber direction).
Location: Murun, Aldan, Republic of Sakha, Siberia, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Tokkoite Crystallography

Axial Ratios:

a:b:c =0.8343:1:0.5684

Cell Dimensions:

a = 10.438, b = 12.511, c = 7.112, Z = 2; alpha = 89.92°, beta = 99.75°, gamma = 92.89° V = 914.17 Den(Calc)= 2.76

Crystal System:

Triclinic - PinacoidalH-M Symbol ( 1) Space Group: P1

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 12.5(1), 10.3(0.45), 5.2(0.42),

Crystal Structure:

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Rozhdestvenskaya I V , Nikishova L V , Lazebnik Yu D , Lazebnik K A , Zeitschrift fur Kristallographie , 189 (1989) p.195-204, The crystal structure of tokkoite and its relation to the structure of tinaksite, Locality: Murun massif, southwestern Yakutia, Russia, Note: anisotropic temperature factors taken from ICSD

Physical Properties of Tokkoite

Cleavage:

[010] Perfect, [110] Very Good

Color:

Brownish yellow, Colorless, Light yellow.

Density:

2.76

Diaphaniety:

Transparent to Translucent

Fracture:

Splintery - Thin, elongated fractures produced by intersecting good cleavages or partings (e.g. hornblende).

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Columnar - Forms columns

Habit:

Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)

Hardness:

4-5 - Fluorite-Apatite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Tokkoite

Gladstone-Dale:

CI meas= -0.001 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.001 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2078,KPDmeas= 0.2078,KC= 0.2077

Optical Data:

Biaxial (+), a=1.57, g=1.577, bire=0.0070, 2V(Meas)=38.

Calculated Properties of Tokkoite

Electron Density:

r_electron=2.75 gm/cc
note: r_Tokkoite=2.76 gm/cc.

Fermion Index

Fermion Index = 0.01259
Boson Index = 0.98741

Photoelectric:

PE_Tokkoite= 4.62 barns/electron
U=PE_Tokkoite x r_electron= 12.72 barns/cc.

Radioactivity:

GRapi = 148.20 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Tokkoite - barely detectable

Tokkoite Classification

Dana Class:

67.2.1.2 (67)Inosilicate Unbranched Chains with W>2

(67.2)with W=5

(67.2.1)Tinaksite group

67.2.1.1 Tinaksite K2Na(Ca,Mn)2(Ti,Fe)O[Si7O18(OH)] P1,P 1 Tri

67.2.1.2 Tokkoite K2Ca4[Si7O18(OH)](F,OH) P1 1

67.2.1.3 Senekevichite! CsKNaCa2TiO[Si7O18(OH)] P1 1

Strunz Class:

VIII/F.22-20 VIII - Silicates

VIII/F - Inosilicates (chain and band) Triplet chains [Si6O15/17]6-/10- and modified triplet bands

VIII/F.22 - Zorite - Tinaksite series

VIII/F.22-10 Zorite Na6Ti5[Si12O34](O,OH)5·11(H2O) C mmm 2/m 2/m 2/m

VIII/F.22-15 Haineaultite! (Na,Ca)5Ca(Ti,Nb)5(Si,S)12O34(OH,F)8·5(H2O) C 222 2 2 2

VIII/F.22-20 Tokkoite K2Ca4[Si7O18(OH)](F,OH) P1 1

VIII/F.22-30 Tinaksite K2Na(Ca,Mn)2(Ti,Fe)O[Si7O18(OH)] P1,P 1 Tri

Other Tokkoite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Print or Cut-and-Paste your Tokkoite Specimen Label here :

Tokkoite

K2Ca4[Si7O18(OH)](F,OH)
Dana No: 67.2.1.2 Strunz No: VIII/F.22-20
Locality:

Notes: