Avogadrite

Avogadrite
Ferruccite (white) on avogadrite (yellow-brownish), picture size: 5 mm
General
CategoryHalide mineral
Formula
(repeating unit)
(K,Cs)BF4
IMA symbolAvg[1]
Strunz classification3.CA.10
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPnma
Unit cella = 8.6588, b = 5.48
c = 7.0299 [Å]; Z = 4
Identification
ColorColorless to white, yellowish to reddish
Crystal habitTabular to platy octagonal crystals, tiny crystals, elongate
LusterVitreous, greasy
DiaphaneityTranslucent
Specific gravity2.9
Optical propertiesBiaxial (-)
Refractive indexnα = 1.3239, nβ = 1.3245, nγ = 1.3247
Birefringenceδ = 0.001
2V angle75°(meas), 58° (calc)
Other characteristicsBitter taste
References[2][3][4]

Avogadrite ((K,Cs)BF4) is a potassium-caesium tetrafluoroborate in the halide class. Avogadrite crystallizes in the orthorhombic system (space group Pnma) with cell parameters a 8.66 Å, b 5.48 Å and c Å 7.03.

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ "Handbook of Mineralogy: Avogadrite" (PDF). The Mineralogical Society of America. Archived from the original (PDF) on 2012-02-18. Retrieved 2010-01-09.
  3. ^ Avogadrite on Mindat.org
  4. ^ Avogadrite data on Webmin

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