Prospech (ASX:PRS) said results from a sampling and assaying program of the historic drill cores from the Korsnäs rare earth elements project in Finland showed heavy rare earth elements results of up to 58 parts-per-million grade of terbium and up to 206 ppm grade of dysprosium, according to an Australian bourse filing on Friday.
Drill core from a total of 471 historical drill holes was preserved by the Geologic Survey of Finland and was validated by recent Prospech diamond core drilling, the filing said.
The results extended the firm's reported resource envelope and the data will be incorporated into a revised resource estimate.
The assays include an intercept of 21.5 meters at 25,827 ppm grade of total rare earth oxides.
A total of 493 more samples are currently undergoing analysis, it said.
Prospech's shares surged 45% in recent trading on Friday.