Chilwa Minerals (ASX:CHW) said a phase one drilling program at the Mpyupyu West prospect in Malawi is 80% complete and intersected a mineralized, free-dig saprolite unit from near-surface, according to a Friday filing with the Australian bourse.

At that completion rate, the target depth to the base of the mineralized interval can now be estimated as averaging eight meters, the company said.

Two rigs continue to drill the prospect and will start infill drilling when the phase one program is complete.

The first two batches of samples have been shipped internationally for a sink-float assay to determine the total heavy mineral content, with results expected late this month.

Chilwa Minerals shares fell nearly 5% in recent Friday trade.