Malladrite
A valid IMA mineral species - grandfathered
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About Malladrite
Alessandro Malladra
Formula:
Na2[SiF6]
Colour:
Pale rose, colorless, white
Lustre:
Vitreous, Greasy
Hardness:
3
Specific Gravity:
2.714
Crystal System:
Trigonal
Name:
Named in honor of Alessandro Malladra (1865, Turin, Italy - 1945, Rome, Italy), professor at the College Mellerio Rosmini-Domodossola; director (1927–1935) of the Vesuvius Observatory. He made scientific descents into Vesuvius that were reported on around the world.
Serafimova et al. (1996) report it from a fumarole with wall temperatures of 60 C and gas temperatures of 100 C. AT other times, with higher temperatures, less malladrite was found.
Unique Identifiers
Mindat ID:
2554
Long-form identifier:
mindat:1:1:2554:2
GUID
(UUID V4):
(UUID V4):
a87a91f0-975c-4e6e-b4ed-40914ca28cb3
IMA Classification of Malladrite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Na2SiF6
Classification of Malladrite
3.CH.05
3 : HALIDES
C : Complex halides
H : Silicofluorides
3 : HALIDES
C : Complex halides
H : Silicofluorides
11.5.2.1
11 : HALIDE COMPLEXES
5 : AmBX6
11 : HALIDE COMPLEXES
5 : AmBX6
8.12.3
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
12 : Fluorborates (BF'4) and fluosilicates (SiF''6)
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
12 : Fluorborates (BF'4) and fluosilicates (SiF''6)
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Mld | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Malladrite
Vitreous, Greasy
Transparency:
Translucent
Colour:
Pale rose, colorless, white
Hardness:
3 on Mohs scale
Hardness:
VHN10=78 - 84 kg/mm2 - Vickers
Comment:
VHN measured on (0001)
Cleavage:
Perfect
{0001}
{0001}
Density:
2.714 g/cm3 (Measured) 2.756 g/cm3 (Calculated)
Comment:
Calculated by Serafimova et al. 1996
Optical Data of Malladrite
Type:
Uniaxial (-)
RI values:
nω = 1.313 nε = 1.309
Birefringence:
weak
Max Birefringence:
δ = 0.004
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Moderate
Chemistry of Malladrite
Mindat Formula:
Na2[SiF6]
Elements listed:
Crystallography of Malladrite
Crystal System:
Trigonal
Class (H-M):
3 2 - Trapezohedral
Space Group:
P3 2 1
Cell Parameters:
a = 8.86 Å, c = 5.04 Å
Ratio:
a:c = 1 : 0.569
Unit Cell V:
342.63 ų (Calculated from Unit Cell)
Morphology:
Crystals prismatic [0001] with basal plane and pyramid.
Tablets showing {0001}, {1120}, and {1010} (Serafimova et al. 1996)
Tablets showing {0001}, {1120}, and {1010} (Serafimova et al. 1996)
Comment:
synthetic
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0009291 | Malladrite | Zalkin A, Forrester J D, Templeton D H (1964) The crystal structure of sodium fluorosilicate Acta Crystallographica 17 1408-1412 |  | 1964 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.426 Å | (67) |
| 4.210 Å | (70) |
| 3.325 Å | (80) |
| 3.053 Å | (67) |
| 2.281 Å | (100) |
| 1.795 Å | (78) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45b : [Other oxidized fumarolic minerals] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 54 : Coal and other mine fire minerals (see also #51 and #56) |
Type Occurrence of Malladrite
Place of Conservation of Type Material:
University of Florence, Florence, Italy, 226/l.
Geological Setting of Type Material:
Lava deposits on an active volcano.
Associated Minerals at Type Locality:
Reference:
Zambonini, F., Carobbi, G. (1926) Sulla presenza del fluosilicato sodico e di quello di potassio tra i prodotti dell'attuale attivita del Vesuvio. Rendiconti, Reale Accademia dei Lincei: 4: 171-175.
Other Language Names for Malladrite
Common Associates
Associated Minerals Based on Photo Data:
| 7 photos of Malladrite associated with Avogadrite | (K,Cs)[BF4] |
Related Minerals - Strunz-mindat Grouping
| 3.CH.10 | Bararite | (NH4)2[SiF6] |
| 3.CH.15 | Cryptohalite | (NH4)2[SiF6] |
| 3.CH.15 | Hieratite | K2[SiF6] |
| 3.CH.20 | Demartinite | K2[SiF6] |
| 3.CH.25 | Knasibfite | K3Na4[SiF6]3[BF4] |
| 3.CH.30 | Heklaite | KNaSiF6 |
Other Information
Notes:
Slightly soluble in cold water; slightly more so in hot water.
Solubility 5.7, 9.9, and 24.6 g/L at 15, 40, and 100 C.
Solubility 5.7, 9.9, and 24.6 g/L at 15, 40, and 100 C.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Malladrite
mindat.org URL:
https://www.mindat.org/min-2554.html
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References for Malladrite
Reference List:
Localities for Malladrite
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Antarctica | |
| Kammerer (2011) |
Iceland | |
| Garavelli et al. (2010) |
Italy (TL) | |
| Accad.Lincei.Rend.Cl.Sci.fis.mat.nat. (1926) +2 other references |
| Russo et al. (2004) | |
| Russo et al. (2004) | |
| GARAVELLI A. et al. (1997) |
Poland | |
| Łukasz Kruszewski (2012) |
Russia | |
| Serafimova et al. (1996) +1 other reference |
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Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia