Lucara Diamond Corp. will spend an additional $163 million and one-and-a-half years to complete the underground expansion at its Karowe mine in Botswana.

The project, which was scheduled to be finished in the second half of 2026, will now be finalized in the first half of 2028, the miner said Sunday. The total cost will reach $683 million, up 25% from the original estimate of $547 million.

The delay and increased costs are due to higher-than-anticipated water volumes in the mine’s sandstone, resulting in unforeseen technical challenges with the structure, Lucara explained. While the project remains economically feasible, the slowdown may affect the miner’s potential revenue. Until the project is finished, the company will have access to lower-grade ore, rather than higher-grade ore from the underground as previously planned, it noted. However, Lucara believes it has enough stockpiles to last through completion of the underground.

“Lucara has made tremendous progress on the Karowe underground expansion project, despite many challenges over the last year,” said Lucara CEO Eira Thomas. “The project continues to deliver strong economics, paying back capital in under three years and adding approximately $4 billion in revenues from an extended mine life out to at least 2040, using conservative diamond-price assumptions.”

 

Image: The Karowe mine in Botswana. (Lucara Diamond Corp.)