The Manitou mercury deposit, 800 metres northeast of the confluence of Relay and Tyaughton creeks, is within foliated greenstone and along contacts between greenstone and ribboned chert of the Mississippian to Jurassic Bridge River Complex (Group). Adjacent rocks include flow breccia and argillite also assigned to the Bridge River Complex, tuffaceous chlorite sandstone, pebble conglomerate and arkosic sandstone of the Lower Cretaceous Lizard Formation, Taylor Creek Group and serpentinite assigned to the Permian and older Shulaps Ultramafic Complex. North to northwest trending dykes of felsite and porphyritic andesite crosscut most rock types; the distribution of dykes is not necessarily coincident with mineralization. The rocks are extremely faulted and principal shear zones trend north and northwest.

Mercury occurs as cinnabar, chiefly with foliated green and purple volcanic rocks (greenstone) along foliation and shear places, and less commonly as: 1) kidney shaped concentrations of cinnabar in calcite veins that cross cut greenstone; 2) discrete dissemination grains of cinnabar within greenstone; and 3) cinnabar in calcite- filled amygdules in amygdaloidal greenstone. Cinnabar is also found along contacts between ribbon chert and greenstone. Cinnabar is commonly accompanied by calcite and less commonly by quartz and rare native mercury, finely crystalline pyrite, an unidentified hydrocarbon material and possibly metacinnabar. Marcasite has tentatively been identified. Recorded production, from 1938 to 1939, is 141.5 tonnes of ore which yielded 542.5 kilograms of mercury (National Mineral Inventory 092O2 Hg1). The irregular distribution of cinnabar makes assessment of the property extremely difficult.

Cinnabar was most likely deposited at a relatively shallow depth from low temperature hydrothermal solutions, probably later than the pervasive calcite veining. Faulting and shearing enhanced the permeability of the greenstone (in particular) and facilitated movement of hydrothermal solutions. The role of igneous dykes in cinnabar deposition and distribution is not known.