Mineral
Wavellita
Al₃(PO₄)₂(OH,F)₃·5H₂O · Fosfatos
A hydrated aluminium phosphate that commonly forms radial, spherical or microcrystalline aggregates. In this piece it is notable for the turquoise-like bluish-green colour, uncommon in more typical wavellite.
Etymology
Named after the English physician and mineralogist William Wavell (1750-1829). “Turquoise” here functions as a colour descriptor, not as a distinct species.