29Metals (ASX:29M) said the restart of mining at its Xantho Extended orebody in Western Australia has been delayed by extra geotechnical works, cutting zinc, gold and silver forecasts while leaving copper guidance unchanged, according to a Thursday Australian bourse filing.

The company stated that ground support upgrades needed to re-enter the decline and production levels are still on schedule for completion in April, although additional work is now underway following revised geotechnical assessments of the impacted areas, per the filing.

The company will develop alternative level access to reduce exposure to higher-stress zones, due for completion in the December quarter, while continuing mining and milling from other ore sources with no change to full-year copper production guidance, the filing said.

The company has cut its full-year outlook for other metals, with zinc now expected at 5,000 to 25,000 tonnes compared with 40,000 to 50,000 tonnes previously, gold at 6,000 to 14,000 ounces compared with 12,000 to 20,000 ounces, and silver at 400,000 to 600,000 ounces compared with 600,000 to 800,000 ounces.

The company also lowered its selling costs guidance to AU$20 million to AU$45 million from AU$50 million to AU$70 million, reflecting the changed production mix, the filing added.