Rodolicoite , Grattarolaite Locality: Castelnuovo Mine, Santa Barbara lignite District, Cavriglia, Valdarno (Val d'Arno), Arezzo Province, Tuscany, Italy Brown crystals of Rodolicoite intimately intergrown with Grattarolaite, pseudo after Vivianite. Field of view 3 mm. Specimen and photo Leon Hupperichs. — Photo: Leon Hupperichs · CC BY-SA 3.0
Rodolicoite
Rodolicoite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Fe³⁺(PO₄).
It crystallizes in the hexagonal crystal system (space group P3_121). It is a member of the Quartz structural group.
Key properties: specific gravity 3.04; Brown streak; Greasy luster.
IMA symbol Rdl, IMA status: approved, named in 1995.
Very rare, in microcrystalline nodules in lignite beds which appear to have naturally burned.
It is found associated with Grattarolaite, heterosite.
The mineral was named to honor Francesco Rodolico (1905–1988), Professor of Mineralogy, Florence University, Florence, Italy.