Mining giants Rio Tinto and Glencore have reportedly held talks to merge, in what would be the largest merger involving an Australian company in history.

The Financial Times reported the two companies held early stage talks in October, but a deal has not been reached.

Under discussion was a full merger or the combining of part of their businesses.

Central to the potential merger is copper, one of the most important metals when it comes to green energy.

Rio Tinto has a market value of $166 billion, while Glencore is valued at $89 billion. 

Rio Tinto is a British-Australian company listed on both the London Stock Exchange and the Australian Securities Exchange.

Glencore is a Swiss company listed in London and Johannesburg, South Africa.

A merger would raise questions about the combined company’s coal operations.

While Rio Tinto sold off their coal assets to focus on other commodities, Glencore still has significant investments in coal.

Glencore is Australia’s largest coal producer, operating in NSW and Queensland.

It also has copper interests in north Queensland, zinc and lead mines in north Queensland and the Northern Territory, and nickel and cobalt in Western Australia.

Rio Tinto’s Australian operations span across every state but South Australia.

Rio’s shares dropped 1.25 per cent when the market opened this morning.

Neither company has commented on the merger talks.