This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications
onto thin films
Figure 3. The high-level value chain for indium
EOL recycling is not currently a significant source of supply.
Recycling from manufacturing waste is better characterized as improved manufacturing efficiency than as a
Indium’s average abundance is estimated to be approximately 0.05 ppm in the continental crust
and 0.072 ppm in the oceanic crust. Indium is found in trace amounts in many minerals and base
metal sulfides, particularly chalcopyrite, sphalerite, stannite, and cassiterite, where it deposits via
ionic substitution. Although indium’s concentration is highest within chalcopyrite, where
concentrations are twice as high as in sphalerite, sphalerite remains the most important indium-
bearing mineral where the indium is recovered as a byproduct from the zinc-sulfide ore (Tolcin
2012a; Schwarz-Schampera and Herzig 2002).
The average indium content of zinc deposits from which it is recovered ranges from less than 1
ppm to 100 ppm. Although the geochemical properties of indium are such that it occurs with
other base metals—copper, lead, and tin, and to a lesser extent with bismuth, cadmium, and
silver—at current indium prices most of these deposits are subeconomic.
Schwarz-Shampera and Herzig (2002) note three principal indium provinces:
The subduction-related western Pacific plate boundaries, especially in east and southeast
The Nazca-South American plate boundary in Bolivia and Peru
Various metallogenic epochs in central Europe covering the Hercynian and Alpine belts.
Other indium-rich areas are the Caledonian/Appalachian belt of North America (New
Brunswick, Canada) and the Archean greenstone belts of Canada and South Africa.
Major geologic hosts for indium mineralization include volcanic-hosted massive sulfide deposits,
sediment-hosted exhalative massive sulfide deposits, polymetallic vein-type deposits, epithermal
deposits, active magmatic systems, porphyry copper deposits, and skarn deposits. The most
important producers of indium today are the volcanic-hosted massive sulfide and the
polymetallic vein-type deposits, which are mined for zinc, lead, tin, and other metals. For more
detailed geologic information on indium, see Schwarz-Schampera and Herzig (2002).
Gibson and Hayes (2011) note that indium is also associated with some silver deposits. Because
silver deposits are generally smaller than many large base metal deposits, indium may well make
up a material part of the total revenue stream. Thus, they view indium production with silver as
an attractive and stable alternative to byproduction from base metals.
Despite its association with a number of other metals, including silver, and because reported
information is lacking,
estimates of indium reserves are based on average indium content of
only a small fraction of the total indium that is potentially recoverable from the Earth’s crust,
they provide a snapshot of known resources, their levels, and their locations.
Based on a pro rata increase in global zinc reserves between 2007 and 2013. Information on the changes to zinc
Zinc reserve data for 2007 from the Canadian Minerals Yearbook (Trelawny and Pearce 2009).
Other countries include Australia, Bolivia, India, Ireland, Kazakhstan, and Mexico. Even though zinc reserves are
available in these countries, no data were available to estimate the corresponding indium reserves. See Appendix A.
Source: Own estimates; Tolcin 2008a, 2008b, and 2014a; Roskill 2010; Trelawny and Pearce 2009.
Not considered in these estimates is the recoverable indium in copper, lead, tin and silver
in these non-zinc deposits are not currently quantifiable, according to Indium Corporation of
America (Indium Corp.) ~15,000 tonnes of indium are contained residues, slag, and tailings, and
annual increases from new residue generation are ~500 tonnes (Mikolajczak 2009). Major
quantities of indium are believed to lie in urban waste in discarded consumer products. In 2008,
the Japanese National Institute for Materials Science estimated that Japan alone had more than
1,700 tonnes of indium in the form of consumer waste
(Ogo and Takeishi 2010).
Because indium has relatively low economic importance for most large mining companies, it bypasses disclosure requirements.
The USGS defines reserves as the known metal content of ores or that is technically and economically capable of being mined
and processed at a profit given conditions at the time of the reserve estimate (Jorgenson and George 2005).
It is not known whether these resources would be economically recoverable given current technologies and prices.