"This paper deals with vertical and lateral ore zoning in the Bolivian tin belt. Three groups of deposits are distinguished: Group A contains deposits without visible connection with intrusive rocks; this includes the antimony deposits and minor deposits . . . most of which are epithermal and show little zonal distribution of minerals. Group B includes deposits closely associated with granitic intrusions, and embraces most of the tungsten deposits and many of the prominent tin deposits . . .; zonal distribution of minerals is particularly well shown in this group. Group C includes those deposits associated with dacitic and rhyolitic intrusive and, to a lesser extent, effusive rocks. Some of the great tin and silver deposits are in this group . . .; zonal distribution of minerals is not so well shown in this group, in part because of 'telescoping' during deposition."

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