Epistolite Mineral Data

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General Epistolite Information

Chemical Formula:

(Na,[ ])2{(Na,Ti)4[Nb2(O,H2O)4Si4O14](OH,F)2}•2H2O

Composition:

Molecular Weight = 758.20 gm

Sodium 11.49 % Na 15.49 % Na₂O

Calcium 1.43 % Ca 2.00 % CaO

Titanium 0.25 % Ti 0.42 % TiO₂

Manganese 0.29 % Mn 0.37 % MnO

Niobium 23.53 % Nb 33.66 % Nb₂O₅

Iron 0.29 % Fe 0.42 % Fe₂O₃

Silicon 14.82 % Si 31.70 % SiO₂

Hydrogen 1.25 % H 11.21 % H₂O

Oxygen 45.24 % O

Fluorine 1.40 % F 1.40 % F

- % F -0.59 % -O=F₂

______ ______

100.00 % 96.09 % = TOTAL OXIDE

Empirical Formula:

Na_3.79Ca_0.27Mn²⁺_0.04Nb_1.92Ti_0.04Fe³⁺_0.04(Si₂O₇)₂O₂(OH)_1.44F_0.56·4(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1897

Locality:

Tugtupagtakorfia, Kvanefield, and Taseq slope, Ilimaussag intrusion, Julianehaab area, southern Greenland. Link to MinDat.org Location Data.

Name Origin:

Named for the Greek for "letter" in allusion to the flat, rectangular form and white color.

Name Pronunciation:

Epistolite + Pronunciation

Epistolite Image

Images:

Epistolite

Comments: Plate-like crystals of pearly white epistolite to 2.7 cm.
Location: Ilimaussaq, Kvanefjeld, Greenland. Scale: 3.5 cm.
© John Veevaert

Epistolite Crystallography

Axial Ratios:

a:b:c =0.7615:1:1.6793

Cell Dimensions:

a = 5.46, b = 7.17, c = 12.041, Z = 1; alpha = 103.63°, beta = 96.01°, gamma = 89.98° V = 455.59 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): 4.33(1), 6.11(1), 2.72(0.8),

Crystal Structure:

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Sokolova E V , Hawthorne F C , The Canadian Mineralogist , 42 (2004) p.797-806, The crystal chemistry of epistolite

Physical Properties of Epistolite

Cleavage:

{001} Perfect, {110} Distinct

Color:

White, Yellowish white, Gray, Light brown.

Density:

2.65 - 2.89, Average = 2.77

Diaphaneity:

Translucent

Fracture:

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

Habit:

Platy - Sheet forms (e.g. micas).

Hardness:

1-1.5 - Talc or a little harder

Luster:

Pearly

Streak:

white

Optical Properties of Epistolite

Gladstone-Dale:

CI meas= -0.006 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.01 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2345,KPDmeas= 0.2337,KC= 0.2323
Ncalc = 1.62 - 1.67

Optical Data:

Biaxial (-), a=1.61, b=1.65, g=1.682, bire=0.0720, 2V(Calc)=80, 2V(Meas)=60.

Calculated Properties of Epistolite

Electron Density:

Bulk Density (Electron Density)=2.71 gm/cc
note: Specific Gravity of Epistolite =2.77 gm/cc.

Fermion Index:

Fermion Index = 0.0075468691
Boson Index = 0.9924531309

Photoelectric:

PE_Epistolite= 35.22 barns/electron
U=PE_Epistolite x rElectron Density= 95.39 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Epistolite is Not Radioactive

Epistolite Classification

Dana Class:

56.02.07.01 (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O

(56.02)with cations in [4] and/or >[4] coordination

(56.02.07)Murmanite group

56.02.07.01 Epistolite (Na,[])2{(Na,Ti)4[Nb2(O,H2O)4Si4O14](OH,F)2}•2H2O P1 1

56.02.07.02 Murmanite (Na,[])2{(Na,Ti)4[Ti2(O,H2O)4Si4O14](OH,F)2}•2H2O P1 ? 1

56.02.07.03 Shkatulkalite! {(Na,Mn,Ca,[])4[Nb2(O,H2O)4Si4O14](OH,F)2}•2(H2O,[]) P 2,Pm,P 2/m Mono

Strunz Class:

09.BE.30 09 - SILICATES (Germanates)

09.B - Sorosilicates

09.BE -Si2O7 groups with additional anions;

09.BE.30 Epistolite (Na,[])2{(Na,Ti)4[Nb2(O,H2O)4Si4O14](OH,F)2}•2H2O P1 1

Other Epistolite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990, CanMin, 42:797) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

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

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Ask about Epistolite here :
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Print or Cut-and-Paste your Epistolite Specimen Label here :

Epistolite

(Na,[ ])2{(Na,Ti)4[Nb2(O,H2O)4Si4O14](OH,F)2}•2H2O
Dana No: 56.02.07.01 Strunz No: 09.BE.30
Locality:

Notes: