Nighthawk Gold (TSX: NHK), which graduated to the TSX in May, is halfway through a 25,000-metre drill program at its Colomac project in the Northwest Territories, and all of the holes reported so far have hit gold mineralization.
The junior has released assays from nine holes that have expanded mineralization at Colomac’s high-grade Zone 1.5 by 90 metres to 350 metres deep, and extended the zone 25 metres north along strike. The zone, which outcrops at surface, is open to depth and along strike.
Hole 17-8 returned a 55.4-metre intercept grading 3 grams gold per tonne from 270 metres downhole, including 19.5 metres grading 5.58 grams gold, and 6.8 metres of 10.45 grams gold.
Colomac drilled its first two holes into the resource gap between Zones 1.5 and 2.0, immediately south.
Zone 2.0 was the site of Colomac’s historic open pit and accounted for most of the mine’s previous gold production, while Zone 1.5 lies 100 metres north of the pit. Zone 2.0 also accounts for a hefty part of Colomac’s inferred resource of 39.81 million tonnes, with an average grade of 1.64 grams gold for 2.10 million contained oz. gold.
The two holes were collared along the southern margin of Zone 1.5 and were designed to test for a possible merger of the two zones, and each one intersected broad mineralization. Hole 17-6B intersected 112 metres of 1.09 grams gold per tonne, including 33.1 metres of 1.84 grams gold, and 5 metres of 5.77 grams gold. Hole 17-6, the shallowest hole, returned 76.1 metres grading 1.17 grams gold, including 23 metres of 2.27 grams gold.
Preliminary results suggest continuity between the zones, Michael Byron, Nighthawk’s president and CEO, said in an interview. Although still early, the assays suggest the zones could merge and develop into a higher-grade domain extending 300 metres on strike. Both zones have only seen shallow drilling and remain open for expansion to depth.
One drill rig will test Zone 1.5 down-plunge and to depth, as well as laterally. It will also drill the gap between the two zones. “It was always intriguing to test the resource gap and see if they merged, and if they did, it would increase the strike length. Given the widths and any opportunities at depth, if it carried similar grade to 1.5, you could have a really good story,” he says.
A second rig has been moved up to Zone 1.0, about 2 km north of Zone 1.5. “We had drilled in the past there and found really good widths — up to 40 metres true width and 1.5 grams gold — so we’re trying to see if we were drilling marginal to something better, and we’ll try to track into some of the better stuff,” Byron says.
(Nighthawk named its zones at Colomac based on their geographical distribution along the sill. Zone 1.0 lies at its northern extent and Zone 3.5 is 7 km south. Zones 2.5 and 3.0 are a couple kilometres south of Zone 1.5.)
A third rig will be moved to the Goldcrest sill, a 4 km mineralization parallel to the Colomac main sill 400 metres west. “It’s also in our resource, so we’re following up on drilling we did in 2014 and 2016,” he says.
For now the drilling focuses on Colomac. The company is also undertaking detailed field mapping and bedrock sampling over much of the Colomac, Goldcrest and Nice Lake sills to hunt for more drill targets. The Nice Lake sill — discovered in February by prospecting geophysical targets outlined from airborne and ground magnetic surveys — is 1.5 km east of Colomac. Nice Lake’s mineralized quartz diorite intrusion is similar to the Colomac and Goldcrest sills.
Later this year the company plans to drill some of the regional targets on its land package within the Indin Lake gold property, 200 km north of Yellowknife.
Byron notes that before the company acquired Colomac in 2012, it was exploring elsewhere on the property, and had found a massive mineralized system running east–west at the north end of its 900 sq. km land package in the Indin Lake greenstone belt.
“We put in five holes in 2011 and got a quarter-of-a-kilometre intersections,” he says. “the size of the system and the structural corridor runs almost 6 km, so we want to know more … we have field-mapping crews who are helping unravel some of the complexities. I’ve hired solid structural geologists who also have industry experience and bring years of work in the Slave Province. They bring an academic background — they’re both PhDs — but they also spend a lot of time in the field, and we need that expertise.”
At Leta Arm, where two historic mines operated in the mid-1940s and early 1950s, there is a shaft and a couple of levels. “No one has been back since,” Byron says. “There are four deposits that sit in a 2.5 km section of a 10 km shear structure that is 500 metres wide and runs north–south through the lake. It was intriguing that you had all that mineralization sitting in a massive shear and no one has paid any attention to it for the last 50 years.
“We’re continuing with the same tact of chasing grade in a near-surface environment at Colomac, finding structures and testing, and stepping out and revisiting our regional deposits, and maturing that story line,” he says. “That was the point of acquiring all that land, and waiting for the market to be receptive to what we’re doing. This will be the first year that we’ve been able to do that.”
At the start of the 2017 drill program, Nighthawk had $36 million in cash. Today its cash balance stands at $33 million.
“We have enough money to pay for everything we want to do this year and next year,” he says.
Nighthawk expects to complete an updated resource estimate early in the first quarter of 2018.
The Indin Lake greenstone belt is the same age and has many of the same mineralization styles as the Timmins camp in Ontario. Unlike Timmins and Canada’s other Archean gold camps, however, the Indin Lake area has seen little exploration, except for brief periods in the 1950s, the late 1980s and the early 1990s.
Colomac has typical Archean gold mineralization. The host rock is a differentiated mafic intrusion, with gold in the silica-rich, upper part of the sill.