The Ben occurrence is located within a large alteration zone which occurs along the contact of Middle Jurassic and Eocene age intrusive bodies. This zone is marked by a large gossan several kilometres in width. The zone separates medium to coarse-grained Eocene biotite granite and Middle Jurassic heterogeneous, fine to medium-grained quartz diorite to diorite to hornblendite. Recrystallized banded, dark and light grey limestone and associated foliated metavolcanic rocks and phyllitic rocks occur as small pendants within the dioritic rocks.

The contact of the two intrusive bodies strikes northwest and is characterized by moderate to pervasive silicification, argillic, sericite and pyrite alteration and a ubiquitous manganese oxide development. Alteration is best developed in the granite and in a non-descript felsic dyke which has intruded along the contact. Shearing or fault movement along the zone is uncertain.

Mineralization consists of disseminations and stringers of molybdenite and lesser chalcopyrite and tetrahedrite in quartz veinlets and stockworks and in pervasive silicified and breccia zones.