
Graulichite-(La), as yellow rhombohedral crystals with thin needles of agardite-(La). Field of view: 0.5 mm. Collection Georges Favreau, photo Pierre Clolus. 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: Pierre Clolus · CC BY-SA 4.0
Graulichite-(La)
Graulichite-(La) is an IMA-recognized mineral species in the arsenate class, with the chemical formula LaFe³⁺₃(AsO₄)₂(OH)₆.
It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Alunite-crandallite structural group.
Key properties: Mohs hardness 3.5; specific gravity 3.907; Light yellow streak; Resinous luster.
IMA symbol Grl-La, IMA status: approved, named in 2021.
Found in a secondary oxidation assemblage in a sulfide deposit.
It is found associated with Agardite-(La), malachite, conichalcite.
The suffix indicates the La analogue of graulichite-(Ce).