Morphology of crystals and aggregates of holotype udinaite and arsenudinaite: (c) complex epitactic intergrowths: “ribbed” parallel aggregates of small flattened forsterite crystals epitactically overgrow large prismatic anhydrite crystal and pseudo-cuboctahedral crystals of udinaite; (c) epitactically overgrow forsterite; (d,e) well-formed almost regular in shape (d) and significantly distorted (e)) crystals of arsenudinaite (light grey) partially ingrown in surface zone of large anhydrite (grey) crystals. SEM image. The image is published in an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( http://creativecommons.org/licenses/by/4.0/ ). — Photo: Pekov, Igor V. and Koshlyakova, Natalia N. and Zubkova, Natalia V. and Belakovskiy, Dmitry I. and Vigasina, Marina F. and Agakhanov, Atali A. and Ksenofontov, Dmitry A. and Turchkova, Anna G. and Britvin, Sergey N. and Sidorov, Evgeny G. and Pushcharovsky, Dmitry Yu. · CC BY-SA 4.0
Arsenudinaite
Arsenudinaite is an IMA-recognized mineral species in the arsenate class, with the chemical formula NaMg₄(AsO₄)₃.
It crystallizes in the tetragonal crystal system (space group I-42d).
Key properties: Mohs hardness 3.5; specific gravity 3.816; White streak; Vitreous luster; optically uniaxial.
IMA symbol Audn, IMA status: approved, named in 2018.
Forms as a sublimate at an active volcanic fumarole.
It is found associated with Udinaite, anhydrite, diopside, hematite, schäferite, berzeliite, svabite, calciojohillerite, tilasite, reznitskyite, ludwigite, rhabdoborite-group borates.
Prefix identifies the arsenic-analogue of udinaite with As > V.