In a June 13 resource update, Nighthawk Gold Corp. said resources at its Colomac gold project in Canada's Northwest Territories grew 24.4% to 2.6 million ounces.
Colomac now hosts inferred resources of 50.3 million tonnes grading 1.62 g/t of gold, compared to a 2013 estimate of 39.8 million tonnes grading 1.64 g/t gold for 2.1 million ounces of gold.
The update includes results from 145 more drillholes than the 2013 resource and used slightly higher cutoff grades in some cases.
Nighthawk increased the cutoff to 0.7 g/t for the Colomac and Goldcrest deposits in the new analysis while retaining a 0.6 g/t cutoff for the Grizzly Bear, 24 and 27 deposits; in 2013, it used a 0.6 g/t cutoff across the board.
The company also refined its deposit model, describing the gold mineralization as "relatively flat lying with a broader distribution than was modeled in the previous resource estimate."
Nighthawk plans to further assess the potential to use lower-cost heap leach technology at Colomac.
"We believe that assessing a heap leach opportunity for Colomac is not only warranted, but if proven, could drastically change the nature of the opportunity," Nighthawk President and CEO Michael Byron said in the statement.
In May, the company said early stage metallurgical testing looking at a heap leach option indicated gold recoveries ranging from 34.30% to 81.8%, while a combination of gravity and cyanide leaching returned recoveries ranging from 96.5% to 98.0%.
Nighthawk started a drill program of at least 25,000 meters at Colomac in early March targeting expansions and an upgrade to resources.