Malladrite Mineral Data

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.

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),

Physical Properties of Malladrite

Color:

Rose, Colorless, White.

Density:

2.714 - 2.755, Average = 2.73

Diaphaniety:

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

Gladstone-Dale:

CI meas= 0.278 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.277 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1139,KPDmeas= 0.1137,KC= 0.1576

Optical Data:

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

Calculated Properties of Malladrite

Electron Density:

r_electron=2.61 gm/cc
note: r_Malladrite=2.73 gm/cc.

Fermion Index

Fermion Index = 0.00697
Boson Index = 0.99303

Photoelectric:

PE_Malladrite= 1.27 barns/electron
U=PE_Malladrite x r_electron= 3.32 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Malladrite is Not Radioactive

Malladrite Classification

Dana Class:

11.5.2.1 (11)Halide Complexes; Alumino-fluorides

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

(11.5.2)Dana Group

11.5.2.1 Malladrite Na2SiF6 P 3₂1 3 2

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

Strunz Class:

III/B.02-10 III - Halogenides

III/B - Double halogenides without water, with [BF4]1-,[SiF6]2- and [AlF6]3-

III/B.02 - Mallardite - Bararite series

III/B.02-10 Malladrite Na2SiF6 P 3₂1 3 2

III/B.02-20 Hieratite K2SiF6 F m3m 4/m 3 2/m

III/B.02-30 Cryptohalite (NH4)2SiF6 F m3m 4/m 3 2/m

III/B.02-40 Bararite (NH4)2SiF6 R 3m 3 2/m

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 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 -École des Mines de Paris

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

Malladrite

Na2SiF6
Dana No: 11.5.2.1 Strunz No: III/B.02-10
Locality:

Notes: