Market report: Investors give Rio Tinto's Arizona cash plan the cold shoulder

Investors on Monday chose not to dig deep into their pockets for Rio Tinto. They ditched the mining giant, seemingly unimpressed by its new plans to invest another $302 million (£231 million) into a long-running US copper project.

The firm said the money for the Resolution Copper scheme in Arizona will be used for additional drilling, studies and infrastructure improvements.

Rio Tinto chief executive JS Jacques said: “The rise of electric vehicles, battery storage, new transmission technology and other green energy innovations are highly copper intensive.

“We need to prepare now to meet this future demand. Resolution will be well positioned to provide North American manufacturers the copper that is essential to their products.”

The City didn’t look quite so enthusiastic about the funding announcement, which brings the total spent by Rio Tinto and its partners on the project up to over $2 billion since 2004. Shares in Rio Tinto dived 68.5p to 4703p.

Other miners to fall on the blue-chip index included Anglo American, down 27p to 2182.5p, and Fresnillo, which lost 10.49p to 785.11p.

The FTSE 100 was 4.33 points lower at 7432.81.

The FTSE 250 was up by 42.94 points to 19,754.01. One of the biggest risers was Energean Oil & Gas, which said it has made a “significant” gas discovery at its Karish North exploration well, offshore Israel.

The update was welcomed by the Israeli minister of energy, Dr Yuval Steinitz, who said: “I congratulate Energean for the significant amount of natural gas discovered in Karish North. I am sure that further discoveries will follow.”

Shares in Energean leapt 76p, or more than 9%, to 856p.

It wasn’t such a good day on the FTSE 250 for Acacia Mining, which fell 4.68p to 187.32p. The miner said gold production for the first quarter at its North Mara mine in Tanzania was 66,324 ounces, down 14% from last year. The firm has been grappling with a long-running tax dispute in the country.

On London’s junior AIM Immotion Group, which produces virtual reality experiences for shopping centres and theme parks, last month released its latest short film: Swimming with Humpback Whales.

It said it has been appointed to install immersive experiences which feature the video, which allows viewers a close-up look at whales migrating from Antarctica, into two major US aquariums in Arizona and Connecticut. Shares in Immotion edged up 0.2p to 5.9p.

The chairman of the Emirates airline group has invested £534,000 in AIM-listed MX Oil. In total £680,000 was raised through a share placing, with Sheikh Ahmed bin Saeed Al Maktoum becoming a holder of 29.86%.

The natural resources investment group’s shares fell 6% to 0.052p.