Collahuasi porphyry has a granodioritic composition, and is between 50 to 300 m wide and up to 100 m long. Masterman (2003) suggests that this porphyry is Permian, with a U-Pb age of 245 Ma ± 12 Ma. Intruding the Collahuasi porphyry is the Rosario porphyry, which is 300 to 500 m wide and up to 1,500 m long.