:Locality: La Reconquistada Claim, Pastrana, Mazarrón-Águilas, Murcia, Spain Size: 2.2 × 0.8 × 0.8 cm Description: Small globular and acicular radiated aggregates of cobaltarthurite, yellowish to orange color, on matrix. Accompanied by arseniosiderite and olivenite. The sample has a small label of Dr. Joan Viñals, one of the describers of the species. Calicata Dolores, Pastrana, Mazarrón-Águilas, Murcia, Spain. Found ca.1999. — Photo: Joan Rosell , from rosellminerals.com · CC BY-SA 4.0
Cobaltarthurite
Cobaltarthurite is an IMA-recognized mineral species in the arsenate class, with the chemical formula CoFe³⁺₂(AsO₄)₂(OH)₂·4H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Arthurite structural group.
Key properties: Mohs hardness 3.5–4; specific gravity 3.22; White to light brown streak; Vitreous (crystals); silky (tufts) luster; optically biaxial.
IMA symbol Caru, IMA status: approved, named in 2001.
Product of oxidation in a near-surface, sulfide-depleted lens.
It is found associated with Pharmacosiderite, conichalcite, olivenite, jarosite, arseniosiderite, scorodite, malachite, azurite, chlorargyrite, mixite, lavendulan.
The name refers to a member of the arthurite group with essential cobalt in the composition.