Niobophyllite Mineral Data

Niobophyllite Mineral Data +

General Niobophyllite Information

Chemical Formula:

K2Na(Fe++,Mn)7(Nb,Ti)2Si8O26(OH)4(F,O)

Composition:

Molecular Weight = 1,394.28 gm

Potassium 5.61 % K 6.76 % K₂O

Sodium 1.65 % Na 2.22 % Na₂O

Titanium 0.69 % Ti 1.15 % TiO₂

Manganese 6.90 % Mn 8.90 % MnO

Niobium 11.99 % Nb 17.16 % Nb₂O₅

Iron 21.03 % Fe 27.05 % FeO

Silicon 16.11 % Si 34.47 % SiO₂

Hydrogen 0.29 % H 2.58 % H₂O

Oxygen 34.71 % O

Fluorine 1.02 % F 1.02 % F

- % F -0.43 % -O=F₂

______ ______

100.00 % 100.89 % = TOTAL OXIDE

Empirical Formula:

K₂NaFe²⁺_5.25Mn²⁺_1.75Nb_1.8Ti_0.2Si₈O_26.25(OH)₄F_0.75

Environment:

Flakes in an albite-arfvedsonite paragneiss.

IMA Status:

Approved IMA 1964

Locality:

Ten Mile Lake, Seal Lake area, Labrador, NF, Canada. Link to MinDat.org Location Data.

Name Origin:

Named for the niobium content and foliated character common to the astrophyllite group.

Niobophyllite Image

Images:

Niobophyllite

Comments: Blackish-brown resinous to silky fibrous niobophyllite coatings on quartz.
Location: Seal Lake area, Labrador, Newfoundland, Canada. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Niobophyllite Crystallography

Axial Ratios:

a:b:c =0.4537:1:0.9814

Cell Dimensions:

a = 5.391, b = 11.88, c = 11.66, Z = 1; alpha = 113.1°, beta = 94.5°, gamma = 103.1° V = 666.95 Den(Calc)= 3.47

Crystal System:

TriclinicSpace Group: P1,P 1

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

By Intensity(I/I_o): 3.506(1), 10.52(0.9), 2.778(0.8),

Physical Properties of Niobophyllite

Cleavage:

[001] Perfect

Color:

Brown.

Density:

3.42

Diaphaniety:

Translucent to Opaque

Habit:

Flakes - Flat, thin crystals or aggregates.

Habit:

Foliated - Two dimensional platy forms.

Hardness:

3-4 - Calcite-Fluorite

Luster:

Vitreous - Adamantine

Optical Properties of Niobophyllite

Gladstone-Dale:

CI meas= -0.012 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.003 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2167,KPDmeas= 0.2199,KC= 0.2173

Optical Data:

Biaxial (-), a=1.724, b=1.76, g=1.772, bire=0.0480, 2V(Calc)=58, 2V(Meas)=60.

Calculated Properties of Niobophyllite

Electron Density:

r_electron=3.35 gm/cc
note: r_{Niobophyllite}=3.47 gm/cc.

Fermion Index

Fermion Index = 0.01304
Boson Index = 0.98696

Photoelectric:

PE_{Niobophyllite}= 27.04 barns/electron
U=PE_{Niobophyllite} x r_electron= 90.48 barns/cc.

Radioactivity:

GRapi = 78.01 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Niobophyllite - barely detectable

Niobophyllite Classification

Dana Class:

69.1.1.4 (69)Inosilicate Chains with Side Branches or Loops

(69.1)with (P=2, and N=4, 2 branches)

(69.1.1)Astrophyllite group

69.1.1.1 Astrophyllite K2Na(Fe,Mn)7Ti2Si8O26(OH)4 P1 1

69.1.1.2 Kupletskite K2Na(Mn,Fe)7(Ti,Nb)2Si8O26(OH)4F C 2/c 2/m

69.1.1.3 Kupletskite-(Cs) (Cs,K)2Na(Mn,Fe,Li)7(Ti,Nb)2Si8O26(OH)4F P1 1

69.1.1.4 Niobophyllite K2Na(Fe,Mn)7(Nb,Ti)2Si8O26(OH)4(F,O) P1,P 1 Tri

69.1.1.5 Zircophyllite K2(Na,Ca)(Mn,Fe)7(Zr,Nb)2Si8O26(OH)4F P1 1

69.1.1.6 Hydroastrophyllite (H3O,K)2Ca(Fe,Mn)5-6Ti2Si8O26(OH)4F P1 1

69.1.1.7 Magnesiumastrophyllite K2Na[Na(Fe,Fe,Mn)Mg2]Ti2Si8O26(OH)4F A2/m 2/m

69.1.1.8 Niobokupletskite! K2Na(Mn,Zn,Fe)7(Nb,Zr,Ti)2Si8O26(OH)4(O,F) P1 1

Strunz Class:

VIII/G.12-80 VIII - Silicates

VIII/G - Intermediate between chain- and layered silicates

VIII/G.12 - Astrophyllite- Kupletskite group

VIII/G.12-20 Magnesiumastrophyllite K2Na[Na(Fe,Fe,Mn)Mg2]Ti2Si8O26(OH)4F A2/m 2/m

VIII/G.12-30 Hydroastrophyllite (H3O,K)2Ca(Fe,Mn)5-6Ti2Si8O26(OH)4F P1 1

VIII/G.12-40 Astrophyllite K2Na(Fe,Mn)7Ti2Si8O26(OH)4 P1 1

VIII/G.12-50 Kupletskite K2Na(Mn,Fe)7(Ti,Nb)2Si8O26(OH)4F C 2/c 2/m

VIII/G.12-60 Kupletskite-(Cs) (Cs,K)2Na(Mn,Fe,Li)7(Ti,Nb)2Si8O26(OH)4F P1 1

VIII/G.12-65 Niobokupletskite! K2Na(Mn,Zn,Fe)7(Nb,Zr,Ti)2Si8O26(OH)4(O,F) P1 1

VIII/G.12-70 Zircophyllite K2(Na,Ca)(Mn,Fe)7(Zr,Nb)2Si8O26(OH)4F P1 1

VIII/G.12-80 Niobophyllite K2Na(Fe,Mn)7(Nb,Ti)2Si8O26(OH)4(F,O) P1,P 1 Tri

Other Niobophyllite Information

References:

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

See Also:

Links to other databases for Niobophyllite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (MinSocAm) 7 -Handbook of Mineralogy (UofA) 8 -MinDAT 9 -MinMax(Deutsch) 10 -MinMax(English) 11 -Mineralienatlas (Deutsch) 12 -QUT Mineral Atlas 13 -École des Mines de Paris

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

Niobophyllite

K2Na(Fe++,Mn)7(Nb,Ti)2Si8O26(OH)4(F,O)
Dana No: 69.1.1.4 Strunz No: VIII/G.12-80
Locality:

Notes: