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Formula: Al2(SeO3)3.6H2O
Hydrated selenite, monoclinic
paramorph of hexagonal
alfredopetrovite
Crystal System: Monoclinic
Specific gravity: 2.93 measured, 2.997 calculated
Hardness: 2 to 3
Streak: White
Colour: Colourless
Environments
Sedimentary environments
Hydrothermal environments
Bernardevansite is a new mineral, approved in 2022 and to date (August 2023) reported only fron the type
locality.
Localities
At the type locality, El Dragón mine, Porco Municipality, Antonio Quijarro Province, Potosí, Bolivia,
bernardevansite occurs as aggregates or spheres of radiating bladed crystals on a matrix consisting of
cobalt-bearing krut'aite –
penroseite. Other associated minerals are
chalcomenite and
clinochalcomenite
(MM 87.407-414).
The deposit consists of small hydrothermal veins, up to 4 cm thick, cutting Paleozoic (541 to 252 million years ago)
sedimentary rocks. The origin of the selenium veins was accomplished by
multiple injections of highly oxidised, metal-rich fluids into faults at the interface between
black shale and
siltstone. Selenides
dominate over sulphides
(Mindat).
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