Demartinite Mineral Data

General Demartinite Information

Chemical Formula:

K2[SiF6]

Composition:

Molecular Weight = 220.26 gm

Potassium 35.50 % K 42.77 % K₂O

Sodium 0.21 % Na 0.28 % Na₂O

Silicon 12.62 % Si 27.01 % SiO₂

Fluorine 51.67 % F 51.67 % F

- % F -21.76 % -O=F₂

______ ______

100.00 % 99.96 % = TOTAL OXIDE

Empirical Formula:

K₂Na_0.02Si_0.99F_5.99

Environment:

Collected in April 2006 from a fumarole at the crater rim. Polymorphous with hieratite.

IMA Status:

Approved IMA 2006 (Dana # Added)

Locality:

La Fossa crater, Vulcano, Eolian Islands, Italy. Link to MinDat.org Location Data.

Name Origin:

Named for Francesco Demartin (b. 1953), who has made significant contributions to the chemistry of metallic clusters and to the crystal structure of Alpine rare-earth minerals and u ranium minerals.

Synonym:

IMA2006-034

Demartinite Image

Images:

Demartinite

Comments: SEM image of a tapering, hexagonal demartinite crystal. (CanMin, v45:1275).
Location: La Fossa crater, Vulcano, Eolian Islands, Italy.. Scale: See Image.
© Canadian Mineralogist

Demartinite Crystallography

Axial Ratios:

a:c = 1:1.63514

Cell Dimensions:

a = 5.6461, c = 9.2322, Z = 2; V = 254.88 Den(Calc)= 2.87

Crystal System:

Hexagonal - Dihexagonal Pyramidal H-M Symbol (6mm) Space Group: P 6₃mc

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

By Intensity(I/I_o): 2.301(1), 4.62(0.75), 2.155(0.54),4.32(0.43), 4.9(0.25), 2.358(0.22), 1.909(0.14), 1.403(0.13),

Physical Properties of Demartinite

Color:

Colorless.

Density:

2.85

Diaphaneity:

Transparent

Habit:

Hexagonal - Six-sided crystal shape in cross-section or habit.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Demartinite

Optical Data:

Uniaxial (-), e=1.34, w=1.35, bire=0.0100.

Calculated Properties of Demartinite

Electron Density:

Bulk Density (Electron Density)=2.76 gm/cc
note: Specific Gravity of Demartinite =2.87 gm/cc.

Fermion Index:

Fermion Index = 0.0059377633
Boson Index = 0.9940622367

Photoelectric:

PE_Demartinite= 4.38 barns/electron
U=PE_Demartinite x r_electron= 12.11 barns/cc.

Radioactivity:

GRapi = 492.98 (Gamma Ray American Petroleum Institute Units)
Concentration of Demartinite per GRapi unit = 0.20 (%)

Estimated Radioactivity from Demartinite - barely detectable

Demartinite Classification

Dana Class:

11.05.02.03 (11)Halide Complexes; Alumino-fluorides

(11.05)where (A)m B (X)6

(11.05.02)Malladrite Group

11.05.02.01 Malladrite Na2SiF6 P 3₂1 3 2

11.05.02.02 Bararite (NH4)2SiF6 R 3m 3 2/m

11.05.02.03 Demartinite! K2[SiF6] P 6₃mc 6mm

Strunz Class:

03.CH.20 03 - HALIDES

03.C - Complex Halides

03.CH -

03.CH.20 Demartinite! K2[SiF6] P 6₃mc 6mm

Other Demartinite Information

References:

NAME( CanMin, v45:1275) PHYS. PROP.(CanMin, v45:1275) OPTIC PROP.(CanMin, v45:1275)

See Also:

Links to other databases for Demartinite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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

Demartinite

K2[SiF6]
Dana No: 11.05.02.03 Strunz No: 03.CH.20
Locality:

Notes:

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