General Information
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 Chemical Formula: |
Na2SiF6 |
| Composition: |
Molecular Weight = 188.06 gm) |
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| Empirical Formula: |
Na2SiF6 |
| Environment: |
Sublimate from fumaroles. |
| Locality: |
Vesuvius, Italy. |
| Name Origin: |
Named for Alessandro Malladra (1865-1945), Italian volcanologist, director of the Vesuvius Observatory. |
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Classification
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| Dana Class: |
11.5.2.1 (11)Halide Complexes; Alumino-fluorides |
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(11.5)where (A)m B (X)6 |
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(11.5.2)Dana Group |
| Strunz Class: |
III/B.02-10 III - Halogenides |
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III/B - Double halogenides without water, with [BF4]1-,[SiF6]2- and [AlF6]3- |
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III/B.02 - Mallardite - Bararite series |
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Crystallography
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| 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 - Trapezohedral H-M Symbol (3 2) Space Group: P321 |
| X Ray Diffraction: |
By Intensity(I/Io): 2.281(1) 3.325(0.8) 1.795(0.78) |
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Physical Properties
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| Color: |
rose, colorless, or white. |
| Density: |
2.714 - 2.755, Average = 2.73 |
| Diaphaniety: |
Transparent |
| Habits: |
Crystalline - Fine - Occurs as well-formed fine sized crystals., Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., |
| Hardness: |
3 - Calcite |
| Luster: |
Vitreous - Greasy |
| Streak: |
white |
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Optical Properties
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| Optical Data: |
Uniaxial (-), e=1.309, w=1.313, bire=0.0040. |
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Other Information
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| References: |
NAME( Ford32) PHYS. PROP.(Dana8) OPTIC PROP.(Dana8) |
| See Also: |
Links to other databases for Malladrite :
1 -Athena Mineralogy
2 - EUROmin Project
3 -MinDat.org Location Data
4 -MinMax
5 -École des Mines de Paris
Search for Malladrite using:
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Ask about Malladrite here :
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Bob's Rockshop Rock Net Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Ask-A-Mineralogist from the Mineralogical Society of America
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Pronunciation Guide 
