A crisis in aluminium’s supply chain has triggered a blistering rally in alumina prices, setting up a potential windfall for companies that produce the raw material known as bauxite, including micro cap Metro Mining.

The latest supply disruption took place in Guinea last week, where bauxite exports from Guinea Alumina Corporation, a subsidiary of Emirates Global Aluminium, were suspended because of customs issues. GAC accounts for nearly 4 per cent of global supply, which is then refined into alumina that is then smelted into aluminium.