Rio Tinto’s revelation that Glencore had contacted it about a potential merger indicates that Glencore’s mega merger-and- acquisition appetite has returned after fully digesting Xstrata. Investec mining analysts see such a merger as being potentially aided by Chinalco, Rio’s 9.8% Chinese shareholder, which is still sore from being prevented five years ago from increasing its Rio shareholding, which would have given it direct stakes in the Australian company’s aluminium, copper and iron-ore assets. As Glencore is iron-ore light and Rio iron-ore heavy, not many competition authority barriers are expected, except in copper where Rio’s La Granja project, in Peru, and Oyu Tolgoi, in Mongolia, would be juicier bait for Chinalco, with which Rio is again toying by pussyfooting on the Simandou iron-ore project, in Guinea.