The $1.4bn Andina Transfer project turned the underground operation into an open pit mine located 3,500 metres above sea level, which holds 30% of Chile’s copper reserves.

Researchers found strange metal behaviour in a material in which electrical charge is not carried by electrons.

The world's largest diamond miner by value is said to have hiked prices by about 8% for big stones and 20% for small ones at the latest sale.

The four locomotives, scheduled for delivery in late 2023, will be supplied by Progress Rail, a unit of Caterpillar, and Wabtec Corp.