Sinclair Gold (ASX:SGC) said the mineral resource estimate for its Mt Henry gold project in Western Australia has doubled to 1.8 million ounces at 1.2 grams per tonne (g/t) grade of gold, according to a Monday filing with the Australian bourse.

The news came after the project added 900,000 ounces in six months since the company acquired it in February, with all of that resource growth coming from the Mt Henry and Selene deposits, per the filing.

The updated mineral resource estimate incorporates drilling results that include 28.6 meters at 2 g/t gold from 224 meters, nearly 27 meters at 1.6 g/t from 207.8 meters, 33.2 meters at 1.6 g/t from 230.7 meters, and 21.4 meters at 1.6 g/t from 159.6 meters.

Sinclair Gold said known mineralization already extends beyond the new 1.8 million-ounce resource, with a fifth drill rig now on-site. Drilling will continue through this year targeting further growth ahead of another resource update before the end of fiscal 2027.

Assays are pending from a further 25 holes drilled outside the resource, with results for many of them expected imminently, the company said.

Sinclair Gold's shares jumped 5% in recent Monday trade.