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    Problem of intermediate collectors of gold
    International Geology Review (1968)
    R. M. Fayzullin
    Analysis of conglomerates at the Kamenskoye goldfield, eastern Zabaykal'ye, shows that some of them are auriferous and are typical “interceptors” (transit collectors) of gold, depending on their petrographic composition and the environmental variables, and that three new variants of the lode-placer sequence are recognizable: a) lode → deluvial placer → interceptor → alluvial placer, (b) lode → interceptor → alluvial → placer, c) interceptor → alluvial placer. – V.P. Sokoloff.
    Lode
    Placer deposit
    Citations (0)
    Distribution of silver and copper in placer gold derived from the northeastern part of the colorado mineral belt
    Economic Geology (1970)
    George A. DesboroughWilliam H. RaymondPaula Jean Iagmin
    Placer gold grains from the modern streams originating in the Colorado Mineral Belt were examined for silver and copper content on a quantitative basis utilizing the electron microprobe. The variation among grains from a particular locality is large, but the mean silver content of the interior of the placer gold grains from each locality and (or) the variation in copper content may be of value in distinguishing lode sources and gold mining districts. Microprobe analysis of the interior of gold grains is independent of chemical actions that affect the border of placer gold grains during their transport history, and it is shown that distinct compositional groups of different lode sources may be identified even in a single sample--information that may aid in recognizing the existence of concealed lodes that once contributed to a placer environment.
    Lode
    Placer deposit
    Microprobe
    Citations (34)
    Platinum-Group Minerals of Pt-Placer Deposits Associated with the Svetloborsky Ural-Alaskan Type Massif, Middle Urals, Russia
    Minerals (2019)
    S. Yu. StepanovР. С. ПаламарчукА. В. КозловД. А. ХанинД. А. Варламов
    The alteration of platinum group minerals (PGM) of eluval, proximal, and distal placers associated with the Ural-Alaskan type clinopyroxenite-dunite massifs were studied. The Isovsko-Turinskaya placer system is unique regarding its size, and was chosen as research object as it is PGM-bearing for more than 70 km from its lode source, the Ural-Alaskan type Svetloborsky massif, Middle Urals. Lode chromite-platinum ore zones located in the Southern part of the dunite “core” of the Svetloborsky massif are considered as the PGM lode source. For the studies, PGM concentrates were prepared from the heavy concentrates which were sampled at different distances from the lode source. Eluvial placers are situated directly above the ore zones, and the PGM transport distance does not exceed 10 m. Travyanistyi proximal placer is considered as an example of alluvial ravine placer with the PGM transport distance from 0.5 to 2.5 km. The Glubokinskoe distal placer located in the vicinity of the Is settlement are chosen as the object with the longest PGM transport distance (30–35 km from the lode source). Pt-Fe alloys, and in particular, isoferroplatinum prevail in the lode ores and placers with different PGM transport distance. In some cases, isoferroplatinum is substituted by tetraferroplatinum and tulameenite in the grain marginal parts. Os-Ir-(Ru) alloys, erlichmanite, laurite, kashinite, bowieite, and Ir-Rh thiospinels are found as inclusions in Pt-Fe minerals. As a result of the study, it was found that the greatest contribution to the formation of the placer objects is made by the erosion of chromite-platinum mineralized zones in dunites. At a distance of more than 10 km, the degree of PGM mechanical attrition becomes significant, and the morphological features, characteristic of lode platinum, are practically not preserved. One of the signs of the significant PGM transport distance in the placers is the absence of rims composed of the tetraferroplatinum group minerals around primary Pt-Fez alloys. The sie of the nuggets decreases with the increasing transport distance. The composition of isoferroplatinum from the placers and lode chromite-platinum ore zones are geochemically similar.
    Lode
    Placer deposit
    Massif
    Platinum group
    Chromite
    Prospecting
    Citations (18)