The Zenith zinc deposit, near Schreiber, Ontario, is a small massive sulphide deposit yielding sphalerite, chalcopyrite, and pyrrhotite. It is hosted by a metadiorite sill. The country rocks are metasediments and metapyroclastic rocks in the foot wall in the western part of the map area, while a mafic metavolcanic unit forms the hanging wall in the northeast part of the area. The entire series is bounded on the west and south by granite. Metamorphic grades vary from high-grade (Winkler, 1974), indicated by migmatites at the contacts with the granite, to amphibolite and greenschist facies (medium and low-grade) in the country rocks.
The main sulphide ore, massive sphalerite, occurs in fracture fillings which form the matrix of a zone of fault breccia. The mechanism of hydraulic fracture is proposed to explain the localization of the sulphide ore. These sulphides are postulated to have been remobilized from sulphide rich xenoliths contained in the sill which originated as metasedimentary-metapyroclastic foot wall rocks.