Lath-shaped pale-greenish crystals of gobelinite from pillar 78b, Cap Garonne, France. Field of view is 1 mm. Photo: Pierre Clolus. Collection: Valérie Galea-Clolus. The image is published in an article ( https://doi.org/10.5194/ejm-32-637-2020 ) distributed under the Creative Commons Attribution 4.0 License. — Photo: Pierre Clolus · CC BY 4.0
Gobelinite
Gobelinite is an IMA-recognized mineral species in the sulfate class, with the chemical formula CoCu₄(SO₄)₂(OH)₆·6H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Ktenasite structural group.
Key properties: Mohs hardness 2.5; specific gravity 2.95; White with a pale green tint streak; Vitreous, sometimes pearly luster; optically biaxial.
IMA symbol Gob, IMA status: approved, named in 2019.
From the weathering of cobaltite-gersdorffite and nearby tennantite under acidic conditions.
It is found associated with Brochantite, cerussite, “guarinoite”, thérèsemagnanite, gordaite.
Alludes to the Old French word gobelin, equivalent to the German word kobold, from which the designation of the element cobalt was derived.