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 5,740 ppm and 22.2 for the Potosi deposits, 2,730 ppm and 7.4 for Bolivar deposit, 2,510 ppm and 17.5 for Siete Suyos-Animas deposits, and 1,290 ppm and 3.3 for San Vicente deposit.The same content and ratio of composite samples of the studied deposits are up to 292 ppm and 4.0 for Potosi deposits, 3,080 ppm and 11.3 for Huari Huari deposit, 100 ppm and 0.3 for Tuntoco deposit, 152 ppm and 1.8 for Porco deposit, 103 ppm and 59.2 for Animas deposit, and 1,160 ppm and 3.7 for Pirquitas deposit. Those of zinc concentrates are as follows: 1,080 ppm and 2.1 at San Lorenzo; 584 ppm and 1.7 at Bolivar; 499 ppm and 1.23 at Porco; 449 ppm and 1.21 at Reserva, and 213 ppm 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.

Indium in cassiterite and ores of tin deposits

“…Russian researchers usually considered Sn mineralization (including indium bearing) of Yakutia, Far East Russia and Vietnam as linked with granodiorite and granite-leucogranite magmatism (Flerov, 1976, Rodionov, 2005, S-and A-granites (Moura et al, 2007;Rodionov et al, 2006, Li et al, 2007Ivanov, 2010;Vladimirov et al, 2012) or I-type granitoids (Gonevchuk et al, 2010). Formation of Sn-In sulfide mineralization of the Dachang district in China is genetically related to Cretaceous subvolcanic granite porphyry (Ishihara et al, 2011).…”

Indium Mineralization in a Sn-Poor Skarn Deposit: A Case Study of the Qibaoshan Deposit, South China

“…Cluster analysis also indicates In, Cd, and Zn belong to the same element group (Figure 6). In/Sn values for the Qibaoshan deposit are greater than for Bolivian Sn-rich In deposits [8] and for the Dachang and Dulong Sn-rich In deposits [6]. Geochemical data for the Qibaoshan deposit indicate the ores are Sn poor, and electron microprobe and reflected-light petrographic studies did not identify any Sn minerals.…”

“…Although In occurs mainly in an isomorphic form in sphalerite, important resources are hosted in Sn-rich deposits. Examples include Sn-polymetallic deposits in south China [5][6][7], Bolivia [8], Japan [2,4], and some Sn-rich Cu-Zn deposits within the Iberian Pyrite Belt [9][10][11] and the Meng'entaolegai Ag-Pb-Zn deposit in north China [12]. Considering these associations with Sn-rich mineralization, could In-rich deposits also occur in Sn-poor environments?…”

Petrochemistry of the Late Cretaceous-Paleogene igneous rocks in the Ikuno-Akenobe mines area, Southwest Japan

“…Sphalerite-rich ores contain up to 4,240 ppm In in these polymetallic quartz vein deposits (Ishihara et al, 2006). Recently, Potosi deposits of Bolivia were reevaluated from a view point of high indium contents in black sphalerite, which was never recovered from the Potosi deposits (Ishihara et al, 2011). The mineralizations at the Ikuno-Akenobe mines are similar to those of the Potosi mine and nearby Porco mine, in terms of the ore mineralogy and related subvolcanic activities.…”