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Ferruccite, Avogadrite - Vesuvius, Italia.jpg
Ferruccite (white) on avogadrite (yellow-brownish), picture size: 5 mm
Category Halide mineral
(repeating unit)
Strunz classification 03.CA.10
Color Colourless white, yellowish to redisch
Crystal system Orthorhombic
Optical properties Biaxial (-)
Refractive index α = 1.3239, β = 1.3245, γ = 1.3247
References [1]

Avogadrite ((K,Cs)BF4) is a potassium-caesium tetrafluoroborate. 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. The mineral is only found as a sublimation product around volcanic fumaroles.[1]


The mineral was discovered by the Italian mineralogist Ferruccio Zambonini in 1926. He analyzed several samples from the volcanic fumaroles close to Mount Vesuvius and from the Lipari islands. He named it after the Italian scientist Amedeo Avogadro (1776–1856).[2]

See also[edit]


  1. ^ a b "Handbook of Mineralogy: Avogadrite" (PDF). The Mineralogical Society of America. Retrieved 2010-01-09. 
  2. ^ Zambonini, Ferruccio (1926). "Sulla presenza, tra i prodotti dell'attuale attività del Vesuvio, di una varietà cesifera del fluoborato di potassio, (On the presence, among the products of Vesuvius, of a caesium-bearing variety of potassium fluoborate), Rend. Accad. Lincei" 6 (III). pp. 644–649.