Catalyst Metals (ASX:CYL) said it has completed grade control drilling for the first 15 months of underground production at its Trident underground deposit in the Plutonic Gold Belt, Western Australia, according to a Thursday Australian bourse filing.

The results were up to 17 meters at 42.7 grams per tonne (g/t) gold and nine meters at 17 g/t gold.

The company said the soon-to-be-completed open pit at the Trident gold deposit brings closer a step change in Plutonic's annual gold production to about 200,000 ounces from roughly 100,000 ounces, with underground gold production from Trident forecast to commence in 2027.

Catalyst Metals said Trident underground reserves stand at 397,000 ounces at 5 g/t gold and resources at 795,000 ounces at 5.3 g/t, with an anticipated annual production rate of about 60,000 ounces for about 10 years.

The company has now developed three mines on the Plutonic Belt, including Plutonic East, the Trident open pit, and K2, with Trident underground set to become the fourth.