Rutile Enriched in Chalcophile Elements (Sb, Sn, Te), and Ti-rich Varieties of Tripuhyute and Cassiterite from Sublimates of Active Fumaroles at the Tolbachik Volcano, Kamchatka, Russia

—The paper contains data on rutile, tripuhyite, and unusual Ti-rich cassiterite found in sublimates of active fumaroles at the Tolbachik volcano, Kamchatka, Russia. In contrast to rutile from other geological environments, fumarolic rutile is enriched in minor chalcophile elements. It contains up to (wt %): 35 Sb 2 O 5 , 59 SnO 2 , 11.3 TeO 3 , 1.9 CuO, 0.4 ZnO, and 18 Fe 2 O 3 . Such high Ti and Cu contents in rutile have not been published before, while minor Te contents have been measured for the first time. Cassiterite containing 19–23 wt % TiO 2 also is a new variety. Hexavalent tellurium is incorporated into the rutile structure together with trivalent iron according to the substitution scheme Te 6+ + 2Fe 3+ → 3Ti 4+ . In fumaroles of the Tolbachik volcano, isostructural rutile, tripuhyite, and cassiterite form a ternary system with several gaps. These minerals were formed at temperatures no lower than 350°C, most likely as a result of interaction between hot volcanic gas (a source for chalcophile elements) and basalt (a source for Ti).