The geology in the Potter Mine area of Ontario consists of very old, Late Archean-aged Kidd-Munro Assemblage rocks (2.711 to 2.719 billion years old). This unit consists of ultramafic and mafic volcanic rocks intruded by mafic to ultramafic dikes and sill-like bodies. Minor felsic volcanic rocks are also present. Polymetallic volcanogenic massive sulfide deposits occur in the Kidd-Munro Assemblage - these are the mining targets at the Potter Mine. Five to six million tons of orebodies are available here. The orebodies consist of seafloor-deposited massive sulfides and sulfide-mineralized sub-seafloor volcanic rocks.

Rocks in the Potter Mine area include a lower komatiite unit, a middle tholeiite unit, and an upper komatiite unit. The latter is well exposed at nearby Pyke Hill, a world-class komatiite locality. The volcanic succession was originally deposited more or less horizontally, but has since been structurally tilted. Volcanic beds are now nearly vertically oriented.

The Potter Mine has 8 levels that go down to 1,100 feet (~300 meters). It was shut down in 1972. The mine made copper concentrate. Recovered metals include copper (Cu) and a little silver (Ag). A drill hole study was done after the mine's shutdown and the subsurface geology has now been explored down to over 3000 feet. Massive sulfide mineralization occurs down to that depth, at least. Sulfides were encountered in the drill cores that contained cobalt (Co). The main mineralization is now recognized to be copper, zinc, and cobalt. The zinc is in the form of sphalerite (ZnS). There is also some silver and low-grade gold.

A volcanogenic massive sulfide (VMS) deposit should not be thought of as one ancient, shut-off, seafloor black smoker. The black smokers had to be long-lived, with multiple inputs of material. The Potter Mine area has stacked, stratiform VMS deposits. They were originally horizontal but are now nearly vertical. The deposits were originally on the seafloor, in an island arc basin environment. Eleven zones of sulfide mineralization have now been defined and 3-D visualized, within the limits of current exploration data (= drill holes).

Pre-shutdown ore samples consist of sulfidic hyaloclastites, plus some massive sulfide samples. The sulfides are dominated by pyrrhotite (Fe1-xS - imperfect iron monosulfide), which is not an ore mineral. Triclinic pyrrhotite and monoclinic pyrrhotite varieties occur at the Potter Mine - one of them is magnetic and the other is not. Some chalcopyrite (CuFeS2) also occurs - this mineral contains copper - it is the principal ore mineral at the mine.