Crystal of shuiskite-(Cr) (a) and a twin with a (001) composition plane (b). SEM (SE) images. The image is published in an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( https://creativecommons.org/licenses/by/4.0/ ). — Photo: Lykova, Inna and Varlamov, Dmitry and Chukanov, Nikita and Pekov, Igor and Belakovskiy, Dmitry and Ivanov, Oleg and Zubkova, Natalia and Britvin, Sergey · CC BY 4.0
Shuiskite-(Cr)
Shuiskite-(Cr) is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₂CrCr₂[SiO₄][Si₂O₆(OH)](OH)₂O.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Pumpellyite structural group.
Key properties: Mohs hardness 6; specific gravity 3.432; Gray-green streak; Vitreous luster; optically biaxial.
IMA symbol Sui-Cr, IMA status: approved, named in 2020.
Found in fracture coatings in chromitite on mine walls.
It is found associated with Calcite, Cr-bearing clinochlore, uvarovite.
The suffix identifies the analog of shuiskite-(Mg) with Cr dominant in the X site.