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Avogadrite

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Formula:
(K,Cs)[BF
 
4
]
System:OrthorhombicColour:Colourless to white, ...
Name:
For Amadeo Avogadro (1776-1856), Professor of Physics at the University of Turin, Turin, Italy.
This page provides mineralogical data about Avogadrite.

Classification of Avogadrite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:3/B.01-20
Nickel-Strunz 10th (pending) edition ID:3.CA.10

3 : HALIDES
C : Complex halides
A : Borofluorides
Dana 8th edition ID:11.2.2.1

11 : HALIDE COMPLEXES
2 : AmBX4
Hey's CIM Ref.:8.12.2

8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
12 : Fluorborates (BF'4) and fluosilicates (SiF''6)
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Type Occurrence of Avogadrite

Type Locality:Mt Vesuvius, Somma-Vesuvius Complex, Naples Province, Campania, Italy
General Appearance of Type Material:minute octagonal crystals and dense crusts
Place of Conservation of Type Material:Natural History Museum, Paris, France (No. 126.148)
Year of Discovery:1926
Geological Setting of type material:Sublimation products around volcanic fumaroles
Associated Minerals at type locality:
SassoliteMalladriteHieratite

Occurrences of Avogadrite

Geological Setting:Volcanic fumaroles

Physical Properties of Avogadrite

Diaphaneity (Transparency):Translucent
Colour:Colourless to white, yellowish to reddish when impure, colourless in transmitted light
Density (calculated):2.9 g/cm3

Crystallography of Avogadrite

Crystal System:Orthorhombic
Class (H-M):mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:Pnma {P21/n 21/m 21/a}
Cell Parameters:a = 8.6588Å, b = 5.48Å, c = 7.0299Å
Ratio:a:b:c = 1.58 : 1 : 1.283
Unit Cell Volume:V 333.57 ų (Calculated from Unit Cell)
Z:4
Morphology:Octagonal crystals, tabular to platy on {001}, may be elongated along [010] or [100].
X-Ray Powder Diffraction:
d-spacingIntensity
3.41 (100)
3.26 (80)
3.06 (75)
2.068 (55)
3.51 (45)
2.801 (40)
2.091 (35)
Comments:X-ray data of synthetic K[BF4] (ICDD 16-378)

Optical Data of Avogadrite

Type:Biaxial (-)
RI values: nα = 1.324 nβ = 1.325 nγ = 1.325
2V:Measured: 75° , Calculated: 58°
Maximum Birefringence:δ = 0.001

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:r > v, strong

Chemical Properties of Avogadrite

Formula:
(K,Cs)[BF
 
4
]
Simplified for copy/paste:(K,Cs)[BF4]
Essential elements:B, F, K
All elements listed in formula:B, Cs, F, K
Analytical Data:Partial analysis of material from Vesuvius, Italy, determined on aqueous extracts from mixtures of sublimates.
K (15.2)
Cs (7.0)
B (12.0)

Relationship of Avogadrite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
3.CA.05Ferruccite
Na[BF
 
4
]
3.CA.10Barberiite
(NH
 
4
)[BF
 
4
]
Related Minerals - Hey's Index Grouping:

- +
8.12.1Ferruccite
Na[BF
 
4
]
8.12.3Malladrite
Na
 
2
[SiF
 
6
]
8.12.4Hieratite
K
 
2
[SiF
 
6
]
8.12.5Cryptohalite
(NH
 
4
)
 
2
[SiF
 
6
]
8.12.6Bararite
(NH
 
4
)
 
2
[SiF
 
6
]

Other Names for Avogadrite

Other Languages:
German:Avogadrit
Avogadroit
Russian:Авогадрит
Spanish:Avogadrita

Other Information

Thermal Behaviour:The mineral becomes cubic above 273°C.
Other Information:Slightly soluble in water.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Avogadrite

Reference List:

- +
Carobbi (1926) Reale accademia nazionale dei Lincei, Rome, Rend.: (6), 4, 382.

Zambonini (1926) Reale accademia nazionale dei Lincei, Rome, Rend.: (6), 3, 644.

Zambonini and Coniglio (1926) Reale accademia nazionale dei Lincei, Rome, Rend.: (6), 3, 521.

American Mineralogist (1927) 12, 232.

Pesce (1930) Gazzetta chimica italiana, Rome: 60: 936.

Finbak and Hassel (1936) Zeitschrift für Physikalische Chemie, Leipzig, Berlin: 32: 433 (isometric polymorph).

Klinkenberg (1937) Recueil des travaux chimiques des Pays-Bas et de la Belgique, Leyden: 56: 36.

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 97-98.

Vlasov, K. A., Ed. (1966): Mineralogy of rare elements, Vol. 2, 65-66.

Brunton, G. (1969): The crystal structure of KBF4. Acta Crystallographica 25, 2161-2162.

Anthony, J. W. et al. (1997): Handbook of Mineralogy, Vol. 3, 32.

Internet Links for Avogadrite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Avogadrite details from Handbook of Mineralogy (PDF)
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  • Localities for Avogadrite

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Italy
     
    • Campania
      • Naples Province
        • Somma-Vesuvius Complex
    Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 98.
    Russo, M., Punzo, I. (2004): I minerali del Somma-Vesuvio, AMI
    • Sicily
      • Messina Province
        • Eolie Islands (Aeolian Islands)
          • Lipari
            • Vulcano Island
    GRAMACCIOLI, C.M., CAMPOSTRINI, I. (2007): Demartinite, a new natural polymorph of K2SiF6 from La Fossa crater, Vulcano, Aeolian Islands, Italy. - Canadian Mineralogist - 45, 1275-1280.
    Russia
     
    • Far-Eastern Region
    Anthony, J. W. et al. (1997): Handbook of Mineralogy, Vol. 3, 32
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