Chile saltpetre is a natural source of  $NaN{O}_3,$  it also contains  $NaI{O}_3.$ The  $NaI{O}_3$ can be used as a source of iodine. Iodine is produced from sodium iodate in a two-step process occurring under acidic conditions:
$\begin{array}{l}I{O}_3^{-}\left(aq\right)+HS{O}_3^{-}\left(aq\right)\stackrel{ }{\to }{I}^{-}\left(aq\right)+S{O}_4^{2-}+H^{+}\left(aq\right)\left(notbalanced\right)\\ I{O}_3^{-}\left(aq\right)+H^{+}\left(aq\right)+I^{-}\left(aq\right)\stackrel{ }{\to }{I}_2\left(s\right)+H_{2}O\left(l\right)\left(notbalanced\right)\end{array}$
 In the illustration, a  $5.00L$ sample of a  $NaI{O}_3\left(aq\right)$ solution containing  $5.80gNaI{O}_3/L$ is treated with the stoichiometric quantity of $NaHS{O}_3$ (no excess of either reactant). Then, a further quantity of the initial $NaI{O}_3\left(aq\right)$  is added to the reaction mixture to bring about the second reaction. 
 $[\text{Molecular weights: }NaI{O}_3=198g/molandNaHS{O}_3=104g/mol)$