Leguernite, Bi12.67O14(SO4)5, a new Bi oxysulfate from the fumarole deposit of La Fossa crater, Vulcano, Aeolian Islands, Italy

Researchers have discovered a new mineral, leguernite (Bi12.67O14(SO4)5), within the high-temperature fumarolic assemblages of La Fossa crater on Vulcano, one of Italy's Aeolian Islands. This colorless to white, transparent mineral exhibits sub-adamantine lustre and is associated with anglesite, balićžunićite, and an unidentified bismuth sulfate. Electron microprobe analysis revealed its chemical composition, while Raman spectroscopy confirmed its anhydrous nature. Leguernite crystallizes in a monoclinic structure (space group P2) with distinct Bi–O blocks and sulfate ions, showing similarities to synthetic Bi14O16(SO4)5 compounds. The discovery honors François 'Fanfan' Le Guern, a renowned volcanologist. This finding contributes to the understanding of mineral formation in volcanic environments.

Garavelli, A., Pinto, D., Mitolo, D., & Bindi, L. (2014). Leguernite, Bi_12.67O₁₄(SO₄)₅, a new Bi oxysulfate from the fumarole deposit of La Fossa crater, Vulcano, Aeolian Islands, Italy. Mineralogical Magazine, 78(7), 1629–1645. https://doi.org/10.1180/minmag.2014.078.7.07