Picture width 0.4 mm. Collection and photograph Christian Rewitzer. From: Torrecillas mine, Salar Grande, El Tamarugal Province, Tarapacá Region, Chile — Photo: Christian Rewitzer · CC BY-SA 3.0
Juansilvaite
A very rare complex sodium-aluminium arsenate-sulfate — one of several new minerals from Chile's Torrecillas mine.
Intro adapted from Wikipedia (CC BY-SA).
Juansilvaite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Na₅Al₃[AsO₃(OH)]₄[AsO₂(OH)₂]₂(SO₄)₂·4H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c).
Key properties: Mohs hardness 2.5; specific gravity 3.01; White streak; Vitreous luster; optically biaxial.
IMA symbol Jsl, IMA status: approved, named in 2015.
From the oxidation of native arsenic and other As-bearing primary phases, followed by later alteration by saline fluids derived from evaporating meteoric water under hyperarid conditions.
It is found associated with Anhydrite, canutite, halite, sulfur, a mahnertite-like phase.
The mineral was named to honor Juan Silva Aguirre (1939-2012), a prominent Chilean mining engineer and successful mining entrepreneur.