At the start of this year the once-mighty global mining industry looked like roadkill: squashed and left for dead by investors. Since then worries about a recession in the West and a hard landing in China have faded, prompting a stunning change in fortunes. In Europe the shares of firms such as Glencore and Anglo American have been the best-performing among large companies in 2016. The same is true in America, where Newmont Mining and Freeport-McMoran have led the S&P 500 index. The industry’s total market value has risen by more than 40%, to $1.9 trillion, since January. September was a particularly good month. One number that hasn’t changed, though, is the industry’s huge debts, run up during the boom years, which still stand at a towering $1.2 trillion. Until more of those are paid off the revival will be far from complete.