General Information
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 Chemical Formula: |
(K,Na)3(Fe++,Mn)6(Nb,Ti)2[Si8O24](O,OH,F)7 |
| Composition: |
Molecular Weight = 1,345.90 gm) |
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| Empirical Formula: |
K2.5Na0.5Fe2+5Mn2+Nb1.8Ti0.2Si8O28OH2F |
| Environment: |
Flakes in an albite-arfvedsonite paragneiss. |
| IMA Status: |
Approved IMA 1964 |
| Locality: |
Ten Mile Lake, Seal Lake area, Labrador, NF, Canada. |
| Name Origin: |
Named for the niobium content and foliated character common to the astrophyllite group. |
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Classification
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| Dana Class: |
69.1.1.4 (69)Inosilicate Chains with Side Branches or Loops |
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(69.1)with (P=2, and N=4, 2 branches) |
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(69.1.1)Astrophyllite group |
| Strunz Class: |
VIII/G.12-80 VIII - Silicates |
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VIII/G - Intermediate between chain- and layered silicates |
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VIII/G.12 - Astrophyllite- Kupletskite group |
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Crystallography
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| Axial Ratios: |
a:b:c =0.4537:1:0.9814 |
| Cell Dimensions: |
a = 5.391, b = 11.88, c = 11.66, Z = 1; alpha = 113.1ø, beta = 94.5ø, gamma = 103.1ø V = 666.95 Den(Calc)= 3.35 |
| Crystal System: |
Triclinic Space Group: P1,P1- |
| X Ray Diffraction: |
By Intensity(I/Io): 3.506(1) 10.52(0.9) 2.778(0.8) |
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Physical Properties
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| Cleavage: |
[001] Perfect |
| Color: |
brown. |
| Density: |
3.42 |
| Diaphaniety: |
Translucent to Opaque |
| Habits: |
Foliated - Two dimensional platy forms., Flakes - Flat, thin crystals or aggregates., |
| Hardness: |
3-4 - Calcite-Fluorite |
| Luster: |
Vitreous - Adamantine |
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Optical Properties
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| Optical Data: |
Biaxial (-), a=1.724, b=1.76, g=1.772, bire=0.0480, 2V(Calc)=58, 2V(Meas)=60. |
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Other Information
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| References: |
NAME( Dana8) PHYS. PROP.(Dana8) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990) |
| See Also: |
Links to other databases for Niobophyllite :
1 -Athena Mineralogy
2 - EUROmin Project
3 -MinDat.org Location Data
4 -MinMax
5 -École des Mines de Paris
Search for Niobophyllite using:
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Ask about Niobophyllite here :
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Bob's Rockshop Rock Net Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Ask-A-Mineralogist from the Mineralogical Society of America
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Pronunciation Guide 
