Inferred Indium Resources of the Bolivian Tin-Polymetallic Deposits

Abstract

Tin-polymetallic base metal deposits of Miocene age in the Eastern Cordillera in Bolivia were studied by ICP/MS and EPMA for major and minor elements, paying an attention to indium concentration of the ore deposits. The highest indium content and 1000 In/Zn ratio of individual ore deposits are 5,740ppm and 22.2 for the Potosi deposits, 2,730ppm and 7.4 for Bolivar deposit, 2,510ppm and 17.5 for Siete Suyos-Animas deposits, and 1,290ppm and 3.3 for San Vicente deposit. The same content and ratio of composite samples of the studied deposits are up to 292ppm and 4.0 for Potosi deposits, 3,080ppm and 11.3 for Huari Huari deposit, 100ppm and 0.3 for Tuntoco deposit, 152ppm and 1.8 for Porco deposit, 103ppm and 59.2 for Animas deposit, and 1,160ppm and 3.7 for Pirquitas deposit. Those of zinc concentrates are as follows: 1,080ppm and 2.1 at San Lorenzo; 584ppm and 1.7 at Bolivar; 499ppm and 1.23 at Porco; 449ppm and 1.21 at Reserva, and 213ppm and 0.61 at Colquiri deposit. Indium occurs mostly in dark colored sphalerite and that of the Potosi deposit was found to have one of the highest concentrations, containing up to 1.27 wt% In. Petrukite was discovered in the Potosi deposit, and indium minerals are expected to occur in the Huari Huari deposit and others with the high 1000 In/Zn ratios. The indium contents of the zinc concentrates and composite samples were applied to the produced and remaining ores, then the total amounts of indium in the Bolivian tin-polymetallic base metal deposits are speculated to be more than 12,000 tons In, which is bigger than that of South China (11,000 tons) and the Japanese Islands (9,000 tons). Sphalerites of the Potosi deposit have one of the highest ranges of indium, similarly to those of the San Vicente deposit. Both the San Vicente and Potosi deposits are rich in silver, implying significance of both silver-polymetallic and tin-polymetallic environments for the concentration of trace amounts of indium. © 2011 The Authors. Resource Geology © 2011 The Society of Resource Geology.