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Tetra-auricupride, ideally AuCu, represents the only species showing the coexistence of Au with an elevated level of Pt, as in the case of a detrital grain studied structurally for the first time, from an ophiolite-associated placer at Bolshoy Khailyk, western Sayans, Russia. We infer that tetra-auricupride can incorporate as much as ~30 mol. % of a “PtCu” component, apparently without significant modification of the unit cell. The unit-cell parameters of platiniferous tetra-auricupride are: a 2.790(1) Å, c 3.641(4) Å, with c/a = 1.305, which are close to those reported for ordered AuCu(I) in the system Au–Cu, and close also to the cell parameters of tetraferroplatinum (PtFe), which both appear to crystallize in the same space group, P4/mmm. These intermetallic compounds and natural alloys are thus isostructural. The closeness of their structures presumably allows Pt to replace Au atoms so readily. The high extent of Cu + Au enrichment is considered to be a reflection of geochemical evolution and buildup in levels of the incompatible Cu and Au with subordinate Pt in a remaining volume of melt at low levels of fO2 and fS2 in the system.
Odonatological results of a trip across the southern Far East of Russia, from nearly the border of North Korea to Khabarovsk from July 1st to 16th, 2014, are presented. In total, 50 species were recorded, including those with limited presence in Russia, such as Paracercion calamorum, P. hieroglyphicum, P. plagiosum (for this species the 3rd Russian locality is reported), Pseudocopera tokyoensis, Stylurus annulatus (2nd Russian locality), Sinictinogomphus clavatus; Trigomphus citimus, Macromia daimoji (3rd Russian locality), M. manchurica, Deielia phaon, Lyriothemis pachygastra (2nd Russian locality). For S. annulatus, M. manchurica and D. phaon the northernmost known localities in the world are reported. D. phaon, earlier reported from one locality in Russia, have been found in five localities in Primorye and for the first time reported for Khabarovskiy Kray in general and Bol'shekhekhtsirskiy State Nature Reserve in particular. A trend of mutual exclusion of two abundant Shaogomphus postocularis epophthalmus and S. schmidti is supposed: the lowermost Ussuri River / Amur River, respectively. Variation in Paracercion spp. and Macromia amphigena fraenata is discussed.