Malladrite Mineral Data

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General Malladrite Information

Chemical Formula:

Na2SiF6

Composition:

Molecular Weight = 188.06 gm

Sodium 24.45 % Na 32.96 % Na₂O

Silicon 14.93 % Si 31.95 % SiO₂

Fluorine 60.62 % F 60.62 % F

- % F -25.52 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Na₂SiF₆

Environment:

Sublimate from fumaroles.

IMA Status:

Valid Species (Pre-IMA) 1926

Locality:

Vesuvius, Italy. Link to MinDat.org Location Data.

Name Origin:

Named for Alessandro Malladra (1865-1945), Italian volcanologist, director of the Vesuvius Observatory.

Name Pronunciation:

Malladrite + Pronunciation

Synonym:

ICSD 16598

PDF 33-1280

Malladrite Image

Images:

Malladrite Avogadrite

Comments: Botryoidal pinkish-white avogadrite with yellow malladrite.
Location: Eruption of 1926, Vesuvius, Campania, Italy. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Malladrite Avogadrite

Comments: Yellow-orange crystalline malladrite with pinkish white avogadrite.
Location: Eruption of 1926, Vesuvius, Campania, Italy. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Malladrite Crystallography

Axial Ratios:

a:c = 1:0.5688

Cell Dimensions:

a = 8.866, c = 5.043, Z = 3; V = 343.30 Den(Calc)= 2.73

Crystal System:

Trigonal - TrapezohedralH-M Symbol (3 2) Space Group: P 3₂1

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

By Intensity(I/I_o): 2.281(1), 3.325(0.8), 1.795(0.78),

Crystal Structure:

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Zalkin A , Forrester J D , Templeton D H , Acta Crystallographica , 17 (1964) p.1408-1412, The crystal structure of sodium fluorosilicate, Locality: synthetic

Physical Properties of Malladrite

Color:

Rose, Colorless, White.

Density:

2.714 - 2.755, Average = 2.73

Diaphaneity:

Transparent

Habit:

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

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Hardness:

3 - Calcite

Luster:

Vitreous - Greasy

Streak:

white

Optical Properties of Malladrite

Optical Data:

Uniaxial (-), e=1.309, w=1.313, bire=0.0040.

Calculated Properties of Malladrite

Electron Density:

Bulk Density (Electron Density)=2.61 gm/cc
note: Specific Gravity of Malladrite =2.73 gm/cc.

Fermion Index:

Fermion Index = 0.0069745004
Boson Index = 0.9930254996

Photoelectric:

PE_Malladrite= 1.27 barns/electron
U=PE_Malladrite x rElectron Density= 3.32 barns/cc.

Radioactivity:

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

Malladrite Classification

Dana Class:

11.05.02.01 (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.05 03 - HALIDES

03.C - Complex Halides

03.CH -

03.CH.05 Malladrite Na2SiF6 P 3₂1 3 2

Other Malladrite Information

References:

NAME( Ford32) PHYS. PROP.(Dana8) OPTIC PROP.(Dana8)

See Also:

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

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Ask about Malladrite here :
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Rockhounds Discussion Group on Yahoo Groups
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Print or Cut-and-Paste your Malladrite Specimen Label here :

Malladrite

Na2SiF6
Dana No: 11.05.02.01 Strunz No: 03.CH.05
Locality:

Notes: