I sing in a choir <a href=" http://www.balanceability.com/azithromycin-to-buy.pdf#practice ">can you order zithromax online </a> Last year, 86pc of Rio Tinto&rsquo;s underlying earning came from iron ore. The second largest commodity exposure is aluminium, which contributed 10pc. The outlook for these two commodities is therefore critical for Rio&rsquo;s future earnings power.