Critical Mineral Resources PLC (LSE:CMRS) said sampling at the Anzar copper-silver project in Central Morocco included exceptionally high copper and silver grades.
One hand sample returned 40.12% copper and 272 grams per tonne (g/t) silver while CMR said channel sample results elsewhere were "outstanding".
In September, 11 samples were collected from three locations across the property and generally the grades were higher than expected, the statement added.
Grades of 15.7% copper and 160g/t silver taken over 1.2 metres were the best of these channel samples, though the findings indicated a consistently elevated silver content.
Charlie Long, chief executive, commented: “Although high-grade copper is visible in the outcropping sandstones and good grades were expected, samples 4, 5, 6 and 10 have significantly exceeded our expectations.
“Our decision to invest in Anzar looks extremely positive, and we look forward to updating shareholders as field work continues.”