Mallestigite Field of view: 40 μm Locality: Mina Casualidad, Baños de Alhamilla, Pechina, Almería, Andalusia, Spain Collection & Photograph Christian Rewitzer 10.2020 — Photo: Christian Rewitzer · CC BY-SA 3.0
Mallestigite
Mallestigite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Pb₃Sb(SO₄)(AsO₄)(OH)₆·3H₂O.
It crystallizes in the hexagonal crystal system (space group P6_3). It is a member of the Fleischerite structural group.
Key properties: Mohs hardness 4; specific gravity 4.91; White streak; Adamantine luster; optically uniaxial.
IMA symbol Mlg, IMA status: approved, named in 1996.
A rare secondary mineral found in the oxidized zone of a hydrothermal polymetallic base-metal deposit containing galena and tetrahedrite (Austria); in weathered metallic slag (Hartz Mountains, Germany).
It is found associated with Anglesite, brochantite, langite, linarite, and schultenite.
The name refers to the town near the dumps from where the mineral was first noted.