They said seven of the nine holes intersected significant mineralisation, including 68.3m of spodumene-pegmatite from 82.7m.
Drill core has been sent for analysis and Pioneer managing director David Crook said the results were expected in March.
"At this time the joint venture will further update the market and describe plans for future drilling, as at this stage mineralisation has not been closed off," he said.
Australian-based Pioneer funded the nine-hole programme as part of its earn-in to Mavis Lake. It is also earning into the second (Raleigh) of ILC's three pegmatite projects in Canada.
Pioneer had A$5.44 million (US$4.3 million) in cash at the end of December and is also exploring its lithium, gold, nickel and cobalt projects in Western Australia.
ILC last month approved a US$17 million budget with majority partner Jiangxi Ganfeng Lithium for continued work at the pair's Mariana lithium brine project in Argentina.
ILC and Ganfeng also recently approved a C$1 million (US$0.8 million) budget for work at their Avalonia lithium pegmatite joint venture in Ireland.