V.V. Zaykov1, 2, L.T. Yablonsky3, P.K. Dashkovsky4, V.A. Kotlyarov1, E.V. Zaykova1, and A.M. Yuminov1, 2 1Institute of Mineralogy, Ural Branch, Russian Academy of Sciences, Ilmensky Reserve, Miass, 456317, Russia 2South Ural State University, Pr. Lenina 76, Chelyabinsk, 454080, Russia 3Institute of Archaeology, Russian Academy of Sciences, Dm. Ulyanova 19, Moscow, 117036, Russia 4Altai State University, Lenina 61, Barnaul, 656049, Russia
An analysis of Early Iron Age gold jewelry from Khankarinsky Dol and Inskoy Dol in the Altai, the Arzhan II royal mound in Tuva, and the Filippovka I and II royal mounds in the Southern Urals, has detected platinoid inclusions similar to those in artifacts from the Near East. Their morphology and composition suggest that gold was mined from placer deposits located near the gold- and platinum-bearing ultramafi c belts. Microinclusions consist of solid solutions of osmium, iridium, and ruthenium. Their nomenclature was determined according to the proportion of these components. Triangular diagrams of microinclusions in artifacts from the Urals reveal four clusters: principal (ruthenium and iridium-osmium) and minor (osmium-ruthenium and iridium-ruthenium), with the latter relating to Os-depleted nanoscale particles surrounding larger ones. Their emergence is due to the impact of molten gold on microinclusions. During melting, heated air in micropores could have caused oxidation of osmium with subsequent assimilation of oxidation products by the melt. Micropores, 1–0.4 ?m in size, were revealed in 5–10 %. This should be taken into account when comparing the composition of microinclusions and minerals from tentative placer deposit sources. Artifacts from Siberia tend to contain mostly ruthenium. Osmium-ruthenium and iridium-osmium trends have also been detected, but not the iridium-ruthenium trend, possibly due to the small sample size in Siberia. The presence of platinoid microinclusions in ancient gold artifacts may suggest that these were manufactured locally.
Keywords: Gold, platinoids, osmium, ancient gold jewelry, microinclusions, placer deposits, ultramafi c belts, molten gold, nomads, Scythian age
