Mineral
Sabugalita
HAl(UO₂)₄(PO₄)₄ · 16H₂O · Fosfatos (Uranilo)
Sabugalite is a hydrated uranyl aluminium phosphate of the A(UO₂)₂(TO₄)₂·8–16H₂O group, with a micaceous, lamellar structure.
It belongs to the same group as autunite; in that pattern A can be Cu, Ca, Ba, Ni, Mn, Fe, or the (HAl) pair, and T is P or As. It is the aluminium-bearing counterpart in that series, but not by a simple Ca-for-Al substitution. Aluminium enters coupled with hydrogen as the (HAl) pair to balance charge.
It typically forms by supergene alteration of other uranium phosphates. Uranospatite readily loses about 10–12 H₂O of hydration and converts chemically to sabugalite. Many old specimens labelled as uranospatite have lost part of their structural water over time and now correspond to sabugalite.
Etymology
From the type locality: Sabugal, Guarda, Portugal.