Riverside Resources Inc. regained a 100% interest in the drill-ready Thor copper project in Sonora, Mexico, after its joint-venture partner, an Antofagasta Plc unit, opted not to move forward with its option to earn a 65% interest in the property.
The option allowed Antofagasta Minerals SA to earn the stake by funding C$5 million in exploration over four years.
The companies completed an initial proof-of-concept drill program to test for a Laramide-aged, porphyry-intrusive system.
The initial drill holes did not return sufficient gold or copper assays for Antofagasta to continue with the partnership, but the limited drilling was successful in hitting alteration and providing support for further exploration, Riverside said June 1.
Riverside owns three quality copper porphyry prospects in northern Mexico and will explore partnership opportunities to advance the copper portfolio as a package or individual prospects going forward.