Astrophyllite Mineral Data

Astrophyllite Mineral Data +

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General Astrophyllite Information

Chemical Formula:

K2Na(Fe++,Mn)7Ti2Si8O26(OH)4

Composition:

Molecular Weight = 1,289.00 gm

Potassium 6.07 % K 7.31 % K₂O

Sodium 1.78 % Na 2.40 % Na₂O

Magnesium 1.41 % Mg 2.35 % MgO

Titanium 7.43 % Ti 12.39 % TiO₂

Manganese 4.26 % Mn 5.50 % MnO

Iron 22.75 % Fe 29.26 % FeO

Silicon 17.43 % Si 37.29 % SiO₂

Hydrogen 0.27 % H 2.45 % H₂O

Oxygen 37.86 % O

Fluorine 0.74 % F 0.74 % F

- % F -0.31 % -O=F₂

______ ______

100.00 % 99.38 % = TOTAL OXIDE

Empirical Formula:

K₂NaFe²⁺_5.25Mn²⁺Mg_0.75Ti₂Si₈O₂₇(OH)_3.5F_0.5

Environment:

Mineral in zircon-bearing syenites.

IMA Status:

Valid Species (Pre-IMA) 1854

Locality:

Langesundfiord, near Brevik, Norway. Link to MinDat.org Location Data.

Name Origin:

From the Greek aster - "star" and fyllon - "leaf."

Synonym:

ICSD 24911

PDF 41-1490

Astrophyllite Image

Images:

Astrophyllite

Comments: Dark brown acicular masses of astrophyllite in calcite matrix.
Location: Khibini, Kola Peninsula, Russia. Scale: 11 x 9 cm.
© Fabre Minerals

Astrophyllite Crystallography

Axial Ratios:

a:b:c =0.4614:1:1.0211

Cell Dimensions:

a = 5.359, b = 11.614, c = 11.86, Z = 1; alpha = 113.16°, beta = 103.04°, gamma = 94.56° V = 659.08 Den(Calc)= 3.25

Crystal System:

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

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

By Intensity(I/I_o): 10.6(1), 3.51(0.8), 2.77(0.6),

Crystal Structure:

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Piilonen P C , McDonald A M , Lalonde A E , The Canadian Mineralogist , 41 (2003) p.27-54, Insights into astrophyllite-group minerals II: Crystal chemistry, Note: sample LAB3, peralkaline nepheline gneiss, Locality: Seal Lake, Labrador, Canada

View Additional jPOWD Structure files for Astrophyllite
[1] [2] [3] [4] [5] [6]

Physical Properties of Astrophyllite

Cleavage:

[001] Perfect

Color:

Brown, Brownish red, Bronze yellow, Gold yellow.

Density:

3.3 - 3.4, Average = 3.34

Diaphaniety:

Translucent to Opaque

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Bladed - Aggregates of thin lath-like crystals (e.g. kyanite).

Habit:

Crystalline - Fine - Occurs as well-formed fine sized crystals.

Habit:

Stellate - Occurs as spherical, radial aggregates radiating from a "star" like point.

Hardness:

3-3.5 - Calcite-Copper Penny

Luminescence:

None.

Luster:

Adamantine - Pearly

Streak:

yellowish brown

Optical Properties of Astrophyllite

Gladstone-Dale:

CI meas= 0.064 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= 0.035 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2164,KPDmeas= 0.21,KC= 0.2244

Optical Data:

Biaxial (+), a=1.68, b=1.7, g=1.73, bire=0.0500, 2V(Calc)=80, 2V(Meas)=70-90. Dispersion none.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Astrophyllite

Electron Density:

r_electron=3.16 gm/cc
note: r_{Astrophyllite}=3.25 gm/cc.

Fermion Index

Fermion Index = 0.02417
Boson Index = 0.97583

Photoelectric:

PE_{Astrophyllite}= 10.45 barns/electron
U=PE_{Astrophyllite} x r_electron= 33.07 barns/cc.

Radioactivity:

GRapi = 85.21 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Astrophyllite - barely detectable

Astrophyllite Classification

Dana Class:

69.1.1.1 (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.12-40 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 Astrophyllite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(AmMin, vol 87, p 999) OPTIC PROP.(Ford32)

See Also:

Links to other databases for Astrophyllite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Amethyst Galleries' Mineral Gallery
5 - Athena
6 - EUROmin Project
7 - Ecole des Mines de Paris
8 - Google Images
9 - Google Scholar
10 - Handbook of Mineralogy (MinSocAm)
11 - Handbook of Mineralogy (UofA)
12 - MinDAT
13 - MinMax(Deutsch)
14 - MinMax(English)
15 - Mineralienatlas (Deutsch)
16 - QUT Mineral Atlas
17 - Ruff.Info
18 - WWW-MINCRYST

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

Astrophyllite

K2Na(Fe++,Mn)7Ti2Si8O26(OH)4
Dana No: 69.1.1.1 Strunz No: VIII/G.12-40
Locality:

Notes: