Data indicating the important role of microorganisms in the formation of nodular monazite (NM) (kularite) of the Kular Range, Republic of Sakha (Yakutia), are presented. The NM contains microorganisms (cyanobacteria) replaced by REE-bearing phosphate (monazite) in the form of stromatolitic microedifices, as well as framboidal Fe sulfides in monazite. The Corg isotopic composition of kularite corresponds to biogenic carbon: the δ13С values vary from –22.2 to –22.3‰.

—The Mokrundya alluvial-placer gold deposit is located in the Verkhoyansk–Kolyma folded region, within the Tuguchak ore–placer cluster. The authors used ore and scanning electron microscopy and chemical–analytical methods to study the typomorphic and mineralogic–geochemical features of gold, minerals of the heavy fraction of the placer, and ore mineralization of the dolerite dike complex stripped in the placer bedrock. Stages of development of the ore-forming system in dolerites have been established. The main productive periods with native gold are associated with the postmagmatic stages: (a) early arsenopyrite–polysulfide stage and (b) gold–bismuth–telluride stage. The latter is composed of bismuth tellurides and sulfotellurides, native gold, bismuth, maldonite AuBi2, and complex Au and Bi intermetallic compounds. The authors hypothesize the sources of placer gold in the alluvial deposits. One of them is the ore mineralization of the dolerite dike complex, and the other is associated with mineralized zones of the Gematitovoe skarn–hydrothermal ore occurrence in the upper reaches of the Mokrundya Stream.

As a result of comprehensive study and laser 40Ar/39Ar dating of sanidines from the rocks of the Talakhtakh diatreme (TD) (Arctic Siberia), it has been found that the formation time of sanidine trachytes (lamproites) corresponds to the isochronous age value of 1497 ± 40 Ma or the weighted average age (as more accurate) of 1476 ± 17 Ma. The obtained age of the TD rocks is fully consistent with the formation time of the main rocks from the Kuonamka large igneous province (LIP). Thus, the Talakhtakh diatreme should be considered as an integral part of the Kuonamka LIP together with widely distributed basaltic sills, dikes, and covers on the Anabar Shield and within the Riphean sedimentary cover.

This study is concerned with the typochemical features of heavy-concentrate platinum from diamond placers of the Mayat-Vodorazdel'nyi site in the Anabar River basin. Platinum occurs there as Fe-Pt solid solutions (ferroan platinum of Ru-Rh specialization, similar to 90%), as well as minor Pd- and Ir-ferroplatinum. Among PGE minerals, Os-Ir-Ru alloys and chengdeite are revealed. Inclusions of PGE minerals are thoroughly studied, and the scales of their spread, the composition of mineral phases, and the relations between them are determined. Ruthenium-containing high-Rh ferroplatinum bears a lot of inclusions of Rh-S composition: Rh-containing PGE thiospinels and sulfides and arsenides of Rh, Ru, and Pt. In low-Rh platinum, mineral inclusions are much scarcer and usually form other parageneses. The mineral compositions in the system Rh-S-Ru indicate to the existence of a long isomorphous series Rh3S4-Ru3S4, with the content of Ru3S4 reaching 15 at.%.