It was all about iron ore and the red earth of Western Australia. Now it's about the bright and stainless glitter of aluminium and China's chronic shortage of electricity.

The battle for control of Rio Tinto has shifted metals — a Chinese state-controlled aluminium producer is in cahoots with an American rival, Alcoa, to acquire 12 per cent of Rio. We have hopped from one primary material, iron oxide, to bauxite and alumina — steps in the process of manufacturing aluminium.

Rio Tinto is a tower of aluminium as well as an iron giant, having recently absorbed Canada's Alcan. It was the merger of Rio and BHP Billiton's iron ore mines that entranced Marius Kloppers, the BHP chief, and appalled the global steel industry, terrifying China's steelmakers.

Days from a bid deadline for Mr Kloppers, a single share deal has made Beijing the dealmaker at the centre of the world's metals industry. Only weeks ago, China was at risk of being stuffed like a dead pheasant shot by a pair of elderly Anglo-Australian miners.

It's a huge sum, $15 billion, but it may seem cheap to Chinalco and its political masters. Chinalco has opened a second front in China's campaign to secure the metals needed by its mills and factories. It is a piece in the struggle by the People's Republic for control of resources — oil, copper, iron ore and aluminium.

China leads the world in aluminium; its smelters account for 28 per cent of supply, but demand surges ahead from manufacturers of cars, drink cans and window frames.

China is still an exporter, but within a year or two, according to Nick Moore, a metals analyst with ABN Amro, the People's Republic will be putting out tentacles into the world market, seeking more metal. Copper, iron ore and now, aluminium — China is short of the building blocks of industry.

It is also short of electricity and the recent power cuts caused by winter storms expose China's weakness. Bauxite is the raw material for aluminium, but the biggest cost is power — hence the emergence of the energy-rich countries Russia and the United Arab Emirates in the aluminium business.

In value terms, an aluminium exporter is selling more electricity than metal.

China cannot afford to use scarce energy to make lumps of metal and so it needs to find alternative sources and Chinalco has spotted Rio and its friend, Alcoa. A tripartite deal would be a colossus.

A combination of Rio, Alcoa and Chinalco would represent about a third of global aluminium production, a prospect that would attract the attention of competition regulators.

It might create as big a row among aluminium consumers in the motor industry as did Mr Kloppers's iron ambitions among the world's steelmakers.

There is no hurry - the shares are safe in a Chinalco subsidiary, appropriately named Shining Prospect. It is now BHP's move. If Mr Kloppers is desperate, he might bid high for Rio and offer the Chinese a quick, dirty profit.

More likely is a stalemate in which BHP makes a modest bid and the four companies, Rio, BHP, Chinalco and Alcoa sit around a table, awkwardly waiting for the first person to speak.

It is like the good old days when Edwardian railroad and mining barons carved up the spoils in a gentlemen's club in Pall Mall.

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