Industrial metals have been on a roller coaster kind of ride in the past couple of years, falling and rising. But for nickel and aluminium multiple pressure points suggest the recent pullback in prices may not sustain. Nickel had a rough 2012, and so far it looks like 2013 will not be much better. Prices have fallen 14 per cent from the start of the year and are down 33 per cent from the peak of $..