Geographic Minerals



Avogadrite, formula [(K, Cs)BF4] is a potassium-caesium tetrafluoroborate in the halide class. It is a potassium and cesium fluoborate occurring in small crystals on Vesuvian lava. Avogadrite crystallizes in the orthorhombic system (space group Pnma) with cell parameters an 8.66 Å, b 5.48 Å and c Å 7.03. Estimated Radioactivity from Avogadrite – barely detectable.

It was named for Amedeo Avogadro (1776–1856), Professor of Physics at the University of Turin, Italy.

General Information

  • Category: Halide mineral
  • Formula: (K, Cs)BF
  • Crystal system: Orthorhombic
  • Crystal class: Dipyramidal (mmm).


  • Color: Colorless to white, yellowish to reddish
  • Crystal habit: Tabular to platy octagonal crystals
  • Luster: Vitreous, greasy
  • Diaphaneity: Translucent
  • Specific gravity: 2.9
  • Transparency: Translucent
  • Density:2.9 g/cm3 (Calculated)


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. As a result, it can only found as a sublimation product around volcanic fumaroles. He named it after the Italian scientist Amedeo Avogadro (1776–1856).


It formed as a sublimation product around volcanic fumaroles. Distribution from Vesuvius, Campania, and on Vulcano, Lipari Islands, Italy. At volcanoes on the Kamchatka Peninsula, Russia.


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