King River Resources (ASX:KRR) completed a systematic drilling program across the historical Mindoolah waste dumps at its Mindoolah gold project in Western Australia, designed to establish definitive volumes and average gold grades, according to a Thursday Australian bourse filing.

The company said a high-resolution aeromagnetic survey has also been completed, with preliminary data from the recently completed low-altitude airborne magnetic survey delivered.

Samples are being prepared for immediate transport to the laboratory, with first assay results expected by the end of July to early August, the company added.

A light mobile reverse circulation rig has transitioned directly into testing shallow exploration extensions and reconnaissance holes beneath historic 1980s pits and 1900s shafts, the company said.

King River Resources' shares fell almost 4% in recent Thursday trade.