Citation: Zaitsev, A. N.; Avdontseva, E. Y.; Britvin, S. N.; Demeny, A.; Homonnay, Z.; Jeffries, T. E.; Keller, J.; Krivovichev, V. G.; Markl, G.; Platonova, N. V.; Siidra, O. I.; Spratt, J.; Vennemann, T. (2013). Oxo-magnesio-hastingsite, NaCa2(Mg2Fe3+3)(Al2Si6)O22O2, a new anhydrous amphibole from the Deeti volcanic cone, Gregory rift, northern Tanzania. Mineralogical Magazine, 77, pp. 2773-2792.