In the Kennedy Lake occurrence area, calcareous sediments of the Upper Triassic Vancouver Group, Quatsino Formation are exposed along the south shore of Kennedy Lake and the north slope of Salmonberry Mountain. Limestone is thoroughly recrystallized to a medium or very coarse grain size and has been bleached white from its normal grey colour. Limited exposures suggest that the stratigraphically higher limestone may form part of a southwest plunging syncline, which has been truncated on the northeast slope of Salmonberry Mountain by granodiorite and quartz monzonite stocks of the Jurassic Island Plutonic Suite.
In general, the limestones are fairly pure with only limited indications of alteration. Rounded grains of quartz and ankerite are commonly present. Close to the intrusive contact, plates and nodules of brucite are disseminated through the altered limestone.
Brucite-bearing carbonate blocks can be seen in the proximity of the Kennedy Lake mine and are also present in the mine dump, accounting for less than 1% of rock by volume. Carbonates and skarn lithologies consisting of serpentine, garnet, amphiboles, magnetite and sulphides are more abundant than brucite-bearing rocks. The extent of brucite zones and brucite grade are unknown. The following table from the CIM Bulletin dated February 2008, showing sample KEN 5-9, indicates that the chemical composition of a representative brucite-bearing boulder from the Kennedy Lake area is equivalent of a dolomite.
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Element SiO2 Al2O3 Fe2O3 MgO CaO Na2O LOI Sum(%)
(%) 0.23 0.13 0.39 21.73 36.12 0.01 41.3 99.92
