Jupiter Mines has announced a "company transforming" deal that delivers the junior explorer a 49.9 per cent stake in a world-class manganese project in South Africa.

The Perth-based company, which lists mining identity Brian Gilbertson and leading South Korean steelmaker Posco as major investors, has entered an agreement for the Tshipi Kalahari Manganese Project.

Shares in the junior were up 4.4 per cent at 24 cents in late afternoon trading.

Under the terms of the proposed Tshipi transaction, Jupiter will issue new shares to the Pallinghurst co-investors, taking their interest in the company up to 85 per cent.

Jupiter's non-executive chairman, Geoffrey Wedlock, said it was a company transforming transaction for Jupiter.

"We have recently announced our intention to be a focused steel feed raw materials company, and this transaction is consistent with this strategy,'' he said in a statement.

Mr Wedlock said Jupiter was also expanding its manganese asset base with an aggressive exploration program on its 890sq km Oakover manganese project in the East Pilbara region of Western Australia.

Mr Gilbertson said Pallinghurst recognised Jupiter's significant potential.

"This transaction provides commodity and geographical diversification, and fast-tracks Jupiter's transition from explorer to a developer and producer. Upon completion, a priority will be to bring Tshipi into production at an early date.''

Jupiter's proposed acquisition of 49.9 per cent of the Tshipi Project has an implied value of $245 million. Mr Gilbertson will join Jupiter's board as non-executive director at the closing of this transaction.

The aim is to fast-track the mine into development and have it producing by 2013.