Hydroniumpharmacoalumite
Hydroniumpharmacoalumite is an IMA-recognized mineral species in the arsenate class, with the chemical formula (H₃O)Al₄(AsO₄)₃(OH)₄·4.5H₂O.
It crystallizes in the cubic crystal system (space group P-43m). It is a member of the Pharmacosiderite structural group.
Key properties: Mohs hardness 2.5; specific gravity 2.486; White streak; Vitreous to adamantine luster.
IMA symbol Hpal, IMA status: approved, named in 2012.
A secondary oxidation product of arsenic-bearing minerals in fractures of alunitized gold-bearing volcanic rocks.
It is found associated with Pharmacoalumite, pharmacosiderite, natropharmacosiderite, hydroniumpharmacosiderite, natropharmacoalumite, jarosite, scorodite, arseniosiderite, yukonite.
As an analog of pharmacosiderite with dominant hydronium and aluminum.