Demartinite Mineral Data
General Demartinite Information
Chemical Formula:
K2[SiF6]
Composition:
Molecular Weight = 220.26 gm
Potassium 35.50 % K 42.77 % K2 O
Sodium 0.21 % Na 0.28 % Na2 O
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:
K2 Na0.02 Si0.99 F5.99
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 63 mc
X Ray Diffraction:
By Intensity(I/Io ): 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:
PEDemartinite = 4.38 barns/electronU=PEDemartinite 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 32 1 3 2
11.05.02.02 Bararite (NH4)2SiF6 R 3 m 3 2/m
11.05.02.03 Demartinite ! K2[SiF6] P 63 mc 6mm
Strunz Class:
03.CH.20 03 - HALIDES
03.C - Complex Halides
03.CH -
03.CH.20 Demartinite ! K2[SiF6] P 63 mc 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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Demartinite
K2[SiF6]
Dana No: 11.05.02.03 Strunz No: 03.CH.20
Locality:
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