Ferri-obertiite explained

Ferri-obertiite
Formula:	Na(Na2)(Mg3Fe^3+Ti)(Si8O22)O2

Ferri-obertiite is an amphibole group mineral that was formally approved by the International Mineralogical Association in 2015. It has the chemical formula Na(Na₂)(Mg₃Fe³⁺Ti)(Si₈O₂₂)O₂.^[1]

Ferri-obertiite is highly sodic and is especially characterized in the presence of oxygen instead of a hydroxy group or fluorine at the W site, which compensates for the relatively high positive charge due to the dominance of ferric iron and presence of titanium. Similar to many other amphiboles, ferri-obertiite is monoclinic with space group C2/m.

The name honors professor Roberta Oberti of the University of Pavia, Italy.^[2]

Notes and References

1. Web site: Ferri-obertiite: Ferri-obertiite mineral information and data. Mindat.org. 2016-03-04.
2. Oberti, R., Boiocchi, M., Hawthorne, F.C., Ball, N.A., and Blass, G., 2015. Ferri-obertiite, IMA 2015-079. CNMNC Newsletter No. 28, December 2015, page ; Mineralogical Magazine 79, 1859–1864