Dingdaohengite-(Ce), an extremely rare mineral species of the chevkinite group, was found as black grains to 2 mm in syenitic pegmatites of Obukhovskiy Uval, South Urals (frst fnd in Russia). Its empirical formula with suggested distribution of cations at octahedral sites: (Ce1.91La1.10Pr0.14 Nd0.13 Ca0.61 Th0.10 )Σ3.99 Fe2+ 1.00(Ti1.07 Mg0.53 Fe2+0.22 Al0.18) Σ2.00 (Ti 1.75Nb0.25 ) Σ2.00 SiO4 22 . Due to the metamict state of the mineral, its x-ray diffraction data were obtained on annealed material. The mineral is monoclinic: a = 13.522(1) Å, b = 5.705(6) Å, c = 11.019(1) Å, β = 100.72(1)°, V = 835.3(1) ų.

Figures 2. Tables 2. References 2.

Key words: dingdaohengite-(Ce), chevkinite group, Obukhovskiy Uval, South Urals, frst fnd in Russia.0.61

A.V. Kasatkin,  Fersman Mineralogical Museum RAS, Moscow, anatoly.kasatkin@gmail.com

S.G. Epanchintsev, Institute of Mineralogy UB RAS, Miass

F. Nestola, Department of Geosciences, University of Padua, Padua, Italy

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