Johanngeorgenstadtite (pink orange) with aerugite (green) and xanthiosite (yellow) on holotype specimen (AMNH 17956); FOV 0.56 mm across. 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: Anthony R. Kampf, Barbara P. Nash, Jakub Plášil, Jason B. Smith, and Mark N. Feinglos · CC BY 4.0
Johanngeorgenstadtite
Johanngeorgenstadtite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Ni²⁺₄.₅(AsO₄)₃.
It is a member of the Alluaudite structural group.
Key properties: Mohs hardness 5; specific gravity 4.801; Pale pink streak; Resinous to subadamantine luster; optically biaxial.
IMA symbol Jgg, IMA status: approved, named in 2020.
Secondary, likely formed from the breakdown of primary nickeline under dry (low relative humidity) and oxidizing (high oxygen fugacity) conditions.
It is found associated with Niasite, aerugite, bunsenite, quartz, rooseveltite, xanthiosite.
The name is derived from the locality, Johanngeorgenstadt, Germany.