"We are just in the initial phase of developing the Ogee Zone for mining and these results confirm the high-grade nature of one of our primary underground targets at Granite Creek," i-80 senior geologist Tyler Hill said.

"Our previously released surface drill hole, iGU21-15, intersected multiple high-grade zones within a broader intercept of 7.4g/t Au across 73.2 metres at depth, demonstrating the substantial upside opportunity of multiple structures at depth that will complement the new South Pacific Zone," he added.

Canaccord Genuity Capital Markets analyst Michael Fairbairn said the results deliver grades well above the current resource and may have a near-term impact on the Granite Creek mine plan.

The current underground resource is 337,000oz of measured and indicated grading 10.37g/t and 319,000oz of inferred grading 13.35g/t, he said.

He noted that i-80 is advancing Granite Creek towards production with ore initially expected to be processed at Nevada Gold Mines' nearby Twin Creeks facility—with production expected to begin in the second half of this year.

The ore is to be processed at i-80's own Lone Tree facility once developed. CG estimates it will come online in 2025.

"We believe i-80's next resource update, following the 2022 drill programme, could add material ounces to Granite," Fairbairn said, adding that it already has one of the highest resource grades out of all underground North American gold projects.

The company's share price was quoted as C$3.50 (US$2.72) on May 5, giving it a market capitalization of C$840.39 million.