[3] The Upper Miocene tonalite stock is a north-south oriented oval, 4.5 by 2.4 km in size, which has undergone hydrothermal alteration.

Glaciation during the Pleistocene carved the U-shaped Los Pelambres valley.

The head of the valley has the highest concentration of ore in a roche moutonnee.

A core of potassium silicate alteration contains the economic copper-molybdenum mineralization.

Sulfide minerals include chalcopyrite, bornite, pyrite and molybdenite.