Coquimbite (Size: 6 cm) Locality: Alfredo pit, Rio Tinto Mines, Minas de Riotinto, Huelva, Andalusia, Spain — Photo: Jose Luis Carrizo · CC BY 3.0
Coquimbite
Coquimbite is an IMA-recognized mineral species in the sulfate class, with the chemical formula AlFe₃(SO₄)₆(H₂O)₁₂·6H₂O.
It crystallizes in the hexagonal crystal system (space group P-31c). It is a member of the Coquimbite structural group.
Key properties: Mohs hardness 2.5; specific gravity 2.11; Vitreous luster; optically uniaxial.
IMA symbol Coq, grandfathered status — known before the IMA’s founding, named in 1841.
Typically a secondary mineral in the oxidized portions of weathering iron sulfide deposits in arid regions; rarely in association with fumarolic activity.
It is found associated with Copiapite, paracoquimbite, voltaite, szomolnokite, römerite.
The name refers to the Coquimbo region, Chile.