DY6 Metals (ASX:DY6) said preliminary metallurgical test work at the Tundulu rare earth elements-phosphate carbonatite project in Malawi on a 120 kilograms composite sample from a high-grade historic trench returned grades of 1.88% total rare earth oxides and 9.1% phosphorus pentoxide, according to a Thursday Australian bourse filing.

The firm added that it considers through further test work, it will be possible to achieve a concentrate grade suitable for treatment via a centralized hydrometallurgical plant.

The phosphate grades of the deposit are amenable to being upgraded into a flotation concentrate, it noted.

DY6 Metals' shares tumbled 8% in recent Thursday trade.