Thermessaite

thermessaite

sassolite

metavoltine

alunite

Images

Formula: K₂AlF₃(SO₄)
Fluoride
Crystal system: Orthorhombic
Specific gravity: 2.77 measured, 2.790 calculated
Streak: White
Colour: Colourless to white
Luminescence: No fluorescence observed under long wave or short wave UV
Environments

Fumeroles

Localities

At the type locality, La Fossa crater, Vulcano Island, Lipari, Eolie Islands, Metropolitan City of Messina, Sicily, Italy, thermessaite is an ino-aluminofluoride-sulphate found in active medium- to high-temperature fumaroles (300 to 350°C) at the rim of the crater. It occurs as sharp translucent crystals up to 0.25 mm in an altered pyroclastic breccia, together with alunite, sassolite, anhydrite and metavoltine (CM 46.3.693-700).
Thermessaite from La Fossa Crater - Image

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