The drilling included a headline grabbing 19.1m grading 7% copper from 45m, with the true width estimated at 12.6m.
Caribou Dome current resource is 2.8 million tonnes at 3.1% copper, while the nearby Zackly resource is 3.4Mt at 1.2% copper and 2 grams per tonne gold.
Scoping work is due to be completed this quarter.
Caribou Dome project is located about 250km northeast of Anchorage in Alaska, USA.
On 25 February 2015, PolarX secured the right to acquire an 80% interest in the weather season-constrained project.
Last year the company broadened its focus to a gold project in Nevada to better optimise its exploration business and help ensure more consistent market newsflow.
PolarX had A$1.6 million cash at the end of the December quarter.
Shares in PolarX were up 6% to 3.7c in morning trade, capitalising the company at $26.4 million.