Adranosite-(Fe), (NH4)4NaFe2(SO4)4Cl(OH)2, a new ammonium sulfate chloride from La Fossa Crater, Vulcano, Aeolian Islands, Italy

Researchers have discovered adranosite-(Fe), a new mineral with the ideal formula (NH4)4NaFe2(SO4)4Cl(OH)2, at La Fossa Crater on Vulcano Island in the Aeolian Islands, Italy. This iron-rich analogue of adranosite forms pale yellow acicular crystals and is structurally characterized by NaO4Cl2 square tetragonal bipyramids linked through helicoidal chains with composition [FeO4(OH)2SO4]n. The mineral's discovery sheds light on its formation in high-temperature, anthropogenic environments, similar to those found in coal dumps. The study employed single-crystal X-ray diffraction and chemical analysis to elucidate its structure, density (measured: 2.18(1) g/cm³; calculated: 2.195 g/cm³), and optical properties, including uniaxial negative birefringence with ω = 1.58(1) and ε = 1.57(1). This finding expands the known mineralogy of volcanic environments and highlights the significance of anthropogenic influences on mineral formation.

Mitolo, D., Demartin, F., Garavelli, A., Campostrini, I., Pinto, D., Gramaccioli, C. M., Acquafredda, P., & Kolitsch, U. (2013). Adranosite-(Fe), (NH4)4NaFe2(SO4)4Cl(OH)2, a new ammonium sulfate chloride from La Fossa Crater, Vulcano, Aeolian Islands, Italy. The Canadian Mineralogist, 51(1), 57–66. https://doi.org/10.3749/canmin.51.1.57