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Cerianite (CeO2) is one of the key minerals controlling the behavior of rare earth elements (REE) in supergene environment, yet little is known about the composition and structure of the mineral. We present Raman spectroscopy and compositional data on regolith cerianite from carbonatite‐related supergene REE deposits. Cerianite showed a low content of impurities, distinguishing from high‐temperature environments, where the mineral is characterized by elevated concentrations of lanthanides other than Ce. The Raman spectra are characterized by the shift of the dominant peak located at 464–465 cm−1 in stoichiometric CeO2 to the lower wavenumbers of 450–455 cm−1, the widening of this peak with the increasing shift, and the presence of additional peaks at 225–230, 284, and 604–613 cm−1. The independence of the main spectral characteristics from the laser wavelength (tested by three lasers: 488, 532, and 633 nm) suggests that the features are genuine and not produced by REE luminescence. The anhydrous composition of supergene cerianite is indicated by the absence of Raman bands in the water‐bearing region of the spectra (2700–3200 cm−1). The spectral features of supergene cerianite, combined with the compositional data, suggest non‐stoichiometry in the mineral and the presence of Ce3+ with oxygen vacancies in the mineral structure. Our observations demonstrate the efficiency of Raman spectroscopy for the identification of the non‐stoichiometric composition of cerianite and its common occurrence in the critical zone.

In this paper, we present the results of a mineralogical study of the ores of the Karalveem deposit in the northeast of Russia (Central and Ruslovy areas). Gold mineralization is characterized by two types of ores: gold-quartz-arsenopyrite (quartz veins with native gold and sulfide mineralization) and gold-sulfide (metasomatites) in gabbrodolerite. In most samples, both types of ores are combined, making these complex ores are of particular interest. The main ore mineral is arsenopyrite; secondary and accessory minerals include pyrite, rutile, ilmenite, galena, chalcopyrite, monazite, sphalerite, and native gold. Native gold in quartz-sulfide and gold-sulfide ore types is present in a free form as microveinlets, micron-size segregations in the host rock, or as microinclusions in sulfides. Both ore types are characterized by the similar chemical composition of ore minerals: the fineness of gold in the gold-sulfide type is 870–900 ‰, in veins – 840–910 ‰. The trace element composition of pyrite and arsenopyrite from metasomatites and quartz veins is also alike. Based on this, it was concluded that the productivity of gold-sulfide and gold-quartz-arsenopyrite ores was formed by a single impulse.