Antofagasta PLC (LSE:ANTO) shares tumbled as first-quarter production of gold, copper and molybdenum all dropped significantly.
Copper output was down by 41% compared to three months earlier at 138,800 tonnes on the back of ongoing drought at Los Pelambres in Chile and lower grades at Centinela.
Grades were also an issue in gold production from Centinela, while the lower ore throughput at Los Pelambres affected molybdenum production.
Iván Arriagada, chief executive, said copper production of 138,800 tonnes and net cash costs of $1.75/lb in the first quarter was in line with the plan for the period.
Copper production is expected to rise quarter-on-quarter through the year, he added, while rising metal prices have helped revenues.
"The copper, gold and molybdenum markets have been strong throughout the quarter, and we expect this to continue as structural supply and demand dynamics support a tight physical market,” said Arriagada.
"With completion of the Los Pelambres desalination plant expected in H2 2022 and no precipitation until the rainy season, full-year guidance is retained at 660-690,000 tonnes of copper at a net cash cost of $1.55/lb.
“Following the completion of the review of the Los Pelambres expansion project, total capital expenditure for the full year is expected to be $1.9 billion, at the top end of the previously guided range of US$1.7-1.9 billion."
Shares fell 8.5% to 1,496p.