Udinaite

udinaite

arsenudinaite

rhabdoborite

calciojohillerite

Images

Formula: NaMg4(VO4)3
Vanadate, forms a series with arsenudinaite
Crystal System: Tetragonal
Specific gravity: 3.613 calculated
Hardness: 3½
Streak: White
Colour: Beige, pale brownish, brownish-yellowish or greyish-brownish
Environments

Fumeroles

Udinaite is a new mineral, approved in 2018 and to date (October 2022) reported only from the type locality.

Localities

At the type locality, the Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik volcano, Kamchatka Krai, Russia, strong fumarolic activity occurs currently. The active, hot Arsenatnaya fumarole features an outstanding mineral diversity, with 144 valid mineral species, 62 of which it is the type locality for. The holotype of udinaite was collected from 3 to 4 m under the surface, the hottest zone of the fumarole at 450 to 470°C. Sublimate incrustations in this zone are up to 4 cm thick and mainly consist of anhydrite, diopside and hematite, typically with significant amounts of the berzeliiteschäferite series and svabite. Udinaite is associated with these minerals together with arsenudinaite, calciojohillerite, tilasite, reznitskyite, ludwigite, rhabdoborite group, forsterite, magnesioferrite, fluorapatite, pliniusite, arsenowagnerite, wagnerite, powellite, scheelite and baryte. (https://doi.org/10.3390/min12070850).
The udinaite occurs as equant tetragonal prismatic–dipyramidal crystals up to 0.15 mm, aggregates up to 1 cm and interrupted crustsup to 2 cm × 2 cm (Mindat).

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