Caribou Dome's metal endowment is now 160% greater with an increase to 224,375 tonnes contained copper grading 3.1% and the addition of a maiden silver resource at 1.5 million ounces at 6.5 grams per tonne.
PolarX was able to reinterpret its understanding of the lenses at the deposit, increasing the resource for the first time since 2017.
Together with the nearby Zackly deposit, the wider Alaska Range project now boasts 269,000t copper, 213,000oz gold and 3.1Moz silver.
The resource is based on a 0.5% copper cut off and is limited to 300m below surface, although the steeply dipping Caribou Dome resource is expected to continue at depth.
The target was discovered in the 1960s, but had been little exploration since the 1970s.
PolarX acquired a right to acquire an 80% interest in 2015 and has completed just two diamond drilling programs, with the last in 2021 suggesting the mineralisation was thicker than previously believed.
PolarX says both resources, which are some 250km northeast of Anchorage, are open in all directions, and could be developed from a central processing hub.
The company has more recently been looking south of the 48th parallel towards the Humboldt Range project in Nevada, where it has defined extensive low-grade gold mineralisation within the Rochester Rhyolite formation close to known mines including the 3Moz gold and 400Moz Rochester mine.
There are also bonanza-grade veins at Star Canyon.
Work continues to generate targets for drilling.
PolarX started the quarter with $1.7 million cash.
The stock has traded between 0.7c and 3.2c over the past year and was last traded at 1.5c, valuing the company at $20 million.