Morella (ASX:1MC) reported a maiden inferred mineral resource estimate of 5.4 million tonnes at 0.2% rubidium oxide for its Mt Edon critical minerals project in Western Australia, according to a Thursday filing with the Australian bourse.

The estimate covers only the Sophie and Miles & June prospect areas, which contain about 8,300 tonnes of rubidium oxide, within a "much broader mineralized pegmatite system" that offers "significant resource growth potential," the company said.

It added that mineralization outcrops or occurs close to surface and remains open beyond the currently defined mineral resource estimate footprint.

The Mt Edon project comprises three exploration licenses. Under the E59/2092 license, the pegmatite-related mineral rights, including lithium, rubidium, caesium and tantalum, are subject to Morella's joint venture with Elevra Lithium (ASX:ELV).

Elevra Lithium's shares fell nearly 5% in recent Thursday trade.