This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications
in 2009 were ~50,000 tonnes, distributed about evenly between Western countries
47%) (Moss et al. 2011).
Given that current refined production is ~770 tpa (as discussed later in this report), the ratio of
reserves to annual production is ~20, implying that these reserves would last ~20 years at current
production rates. For many minerals, a reserve/production ratio of 10–20 is not uncommon, so
indium’s ratio is not unusual. One should not infer from this ratio that geologic sources of
indium will be depleted in 2 decades. Reserves change over time. As mining depletes reserves,
mining companies have an incentive to find and develop additional reserves—a process that
results in reserve/production ratios that remain reasonably constant over time. For example, the
USGS estimate of indium reserves at year-end 1997 was 2,600 tonnes, yielding a 1997
reserve/production ratio of 11. Indium reserves at year-end 2013 were approximately six times
larger than they were in 1997.
These are crude estimates of reserves; however, they provide a sense of where mining of indium-
bearing ores is likely to be concentrated over the next several decades. Although most reserves
and resources are in China, there is a significant diversity of other potential locations for mining
indium-bearing ores. Also, the estimates of resources and reserves focus on primary sources of
indium only; if one considers future increases in the recycling of consumer and manufacturing
waste, the geographic dispersion of indium sources could diversify significantly.
Mine production figures are not publically available for indium as a byproduct of zinc mining
and processing, but Roskill (2010) estimates global mine production of indium from zinc mine
production statistics for 2009.
Table 2 shows the Roskill estimates for mine production of indium as well as our estimates for
2013. In arriving at these estimates, Roskill assumed that sphalerite ores contain 67% zinc and
15–50 ppm indium.
The indium content of zinc ores mined in 2009 and 2013 is ~481 and 629 tonnes, respectively.
Growth of indium production between 2009 and 2013 represents a compounded annual growth
rate (CAGR) of 6.9%. By comparison, zinc production grew at a CAGR of 4.8% over the same
period (Appendix A), indicating that the production of indium-bearing zinc ores grew faster than
The country concentration of mine production is similar to that of the concentration of reserves.
The main sources of zinc ores are China, Peru, Canada, Australia, and the United States. These
five countries accounted for 76% of the potentially recoverable indium from zinc ores in 2009
and 79% in 2013. These same countries represented ~82% and ~75% of indium reserves in 2007
Although reserves (classified as “proven” and “probable” by most reporting codes) are the fraction of known resources that are
“inferred”) represent known resources that are not economic to classify as reserves or are too speculative because the geological
sampling information is preliminary.
and 2013, respectively (Table 1). China has a lower market share with 59% of total mine
production, compared to a 70% share of reserves.
Table 2. Global Estimates of Mined Indium From Zinc Ores, 2009 and 2013 (tonnes)
Estimates zinc content of concentrates and shipping ores.
Roskill (2010) believes that the actual amount of indium contained in the zinc ores may be much higher than estimated because
some deposits contain much higher levels of indium than assumed.
2013 estimates of indium production derived using Roskill (2010) estimates of indium concentration applied to 2013 USGS zinc
Roskill (2010) does not give an exact estimate of indium concentration in zinc ores. A value of 20 ppm is used, because this
Estimates for 2009 zinc mine production from the Canadian Minerals Yearbook (Trelawny and Pearce 2009) and 2013
Source: Own calculations; Tolcin 2010a, 2010b, 2014b; Roskill 2010; Trelawny and Pearce 2009
As previously discussed, indium is also produced from metals such as copper, tin, and silver. As
60–65 tonnes to annual global mine production (Roskill 2010). Potential known sources include
copper ores mined in Russia and China, as well as tin ores mined in China. In addition,
Falconbridge Ltd. produced indium from dusts recovered during copper smelting at its Canadian
operations. Between 2009 and 2013, copper and tin production grew at rates of ~3.2% and ~–
7.0%, respectively. Assuming that indium production from these sources has kept in line with
main product production, total world mine production of indium from copper and tin resources
was ~68–74 tonnes in 2013 (Table 3).
Copper and tin