General Information
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 Chemical Formula: |
K2Ca4[Si7O18(OH)](F,OH) |
| Composition: |
Molecular Weight = 758.60 gm) |
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| Empirical Formula: |
K2Ca4Si7O18(OH)1.25F0.75 |
| IMA Status: |
Approved IMA |
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Classification
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| Dana Class: |
67.2.1.2 (67)Inosilicate Unbranched Chains with W>2 |
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(67.2)with W=5 |
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(67.2.1)Dana Group |
| Strunz Class: |
VIII/F.22-20 VIII - Silicates |
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VIII/F - Inosilicates (chain and band) Triplet chains [Si6O15/17]6-/10- and modified triplet bands |
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VIII/F.22 - Zorite - Tinaksite series |
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Crystallography
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| Axial Ratios: |
a:b:c =0.8343:1:0.5684 |
| Cell Dimensions: |
a = 10.438, b = 12.511, c = 7.112, Z = 4; alpha = 89.91ø, beta = 99.75ø, gamma = 92.82ø V = 914.23 Den(Calc)= 5.51 |
| Crystal System: |
Triclinic - Pinacoidal H-M Symbol ( -1) Space Group: P1- |
| X Ray Diffraction: |
By Intensity(I/Io): 12.5(1) 10.3(0.45) 5.2(0.42) |
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Physical Properties
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| Cleavage: |
[???] Perfect |
| Color: |
brownish yellow, colorless, or light yellow. |
| Density: |
2.76 |
| Diaphaniety: |
Transparent to Translucent |
| Hardness: |
4-5 - Fluorite-Apatite |
| Luster: |
Vitreous (Glassy) |
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Optical Properties
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| Optical Data: |
Biaxial (+), a=1.57, g=1.577, bire=0.0070, 2V(Meas)=38. |
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Other Information
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| References: |
PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990) |
| See Also: |
Links to other data for Tokkoite :
1 -Athena Mineralogy
2 - EUROmin Project
3 -MinDat.org Location Data
4 -MinMax
5 -WWW-MINCRYST
6 -École des Mines de Paris
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