ASX-listed gold minnow ABM Resources has announced an almost 50 per cent downgrade in gold at its Buccaneer deposit in the Northern Territory.

The Perth-based company (ASX: ABU) announced an updated resource for Buccaneer of 10 million tonnes grading at 1.82 grams per tonne for 585,000 ounces gold above a 1g/t cut-off. The resource was independently estimated by Optiro.

This compares to the previous resource estimate conducted by ABM back in 2013 of 15.3 million tonnes grading at 2.23 grams per tonne for 1.1 million ounces of gold.

The 2017 Buccaneer Resource model update was triggered after the current management reviewed diamond drilling underpinning the interpretation. The resource now includes drilling completed after the 2013 resource update including 48 aircore holes and 4 diamond holes.

ABM said the 2017 resource estimate only includes higher confidence drilling methods including reverse circulation, diamond and aircore drilling.

The company also carried out re-logging of three Buccaneer diamond holes, substantial validation of the database data, and the review of the geological model.

“This work showed that mineralisation is challenging to predict from drill hole to drill hole and the mineralisation tonnages reported in 2013 are difficult to support with the current drilling density,” ABM said.

The Buccaneer porphyry gold deposit is part of the Twin Bonanza Project area in the Northern Territory and located 5km north-northwest of the Old Pirate High-Grade Gold Deposit.

Shares in ABM were trading at 11c in morning trade.