Alunogen

Alunogen, a white fibrous sulfate mineral, is formed by reaction of sulfates from decomposing sulfides with aluminous minerals. Alurogen is hydrated aluminum sulfate, formulated Al2SO4�17H2O. It typically occurred as an efflorescence of volcanic action and filled in the crevices of pyrite deposits in coal seams, alum shalesor or slates, as well as in the gossan. Weathered sulfide ore deposits and hairlike sulfate minerals from volcanic fumaroles are called Haarsalz (hair salts). The low temperature fumaroles of volcanic activity represents a low eruption thus it may be an indicator to show whether the volcano will re-erupt or not.