Redefinition of coquimbite, AlFe3+3(SO4)6(H2O)12⋅6H2O. (2nd April 2020)

• Record Type: Journal Article
• Authors: Mauro, Daniela; Biagioni, Cristian; Pasero, Marco; Skogby, Henrik; Zaccarini, Federica
• Is Part Of: Mineralogical magazine. Volume 84:Number 2(2020)
• Page Start: 275
• Page End: 282
• Publication Date: 2020-04-02
• Subjects: coquimbite, -- iron, -- aluminium, -- sulfate, -- paracoquimbite, -- aluminocoquimbite, -- coquimbite group; Mineralogy -- Periodicals; Mineralogy -- Great Britain -- Periodicals; 549.05
• DOI: 10.1180/mgm.2020.15
• Languages: English
• ISSNs: 0026-461X

Abstract

Abstract: Coquimbite, AlFe 3+ 3 (SO4 )6 (H2 O)12 ⋅6H2 O, was considered as a pure Fe 3+ hydrated sulfate. However, previous mineralogical studies pointed out the occurrence of essential Al, occupying a distinct site in the crystal structure of this mineral. Through the critical re-examination of the available literature and new crystal-chemical data collected on a specimen from the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy, the chemical formula of coquimbite has been revised, taking into account the occurrence of Al. Coquimbite has a homeotypic relationship with paracoquimbite, Fe4 (SO4 )6 (H2 O)12 ⋅6H2 O; both mineral species belong to the coquimbite group. On the contrary, aluminocoquimbite, Al2 Fe2 (SO4 )6 (H2 O)12 ⋅6H2 O, has a different topology and does not belong to that group.