We regret that an error was introduced in Table 2 in Spira et al. (Reference Spira, Kirkby, Kujirakwinja and Plumptre2017) during the production process. The correct unit for the mean price of gold is USD g−1, not USD kg−1. The correct table is presented below.
Table 2 Mean sale price of cassiterite, coltan and gold at various points along the value chain. Blank cells indicate no data.

*InfoMine (2015)