On the southeast side of the Frenchman's Cap Dome lies a series of nepheline-bearing gneisses complexly folded within a sequence of biotite, diopside and sillimanite schists and gneisses, amphibolites, quartzites and some calc-silicate rocks. The alkaline gneisses comprise three units. A variable syenitic gneiss occurs which is usually silica-saturated, but contains a little altered nepheline here and there, occasional analcime, cancrinite, biotite, aegirine, diopside and hastingsitic amphibole and carbonate, but with dominant K-feldspar. This passes into a unit of alkaline amphibolite and amphibole-biotite schist with nepheline. The third, central zone is a syenite with 15-60% nepheline, usually altered, aegirine (30%), microcline, perthite, and accessory cancrinite, sphene and zircon; locally fluorite and rinkite are significant. Nepheline-bearing lamprophyric dykes occur.
CURRIE, K.L. 1976a. The alkaline rocks of Canada. Bulletin, Geological Survey of Canada, 239: 1-228.
FYLES, J.T. 1970. The Jordon River area near Revelstoke, British Columbia. Bulletin, British Columbia Department of Mines and Petroleum Resources, 57: 1-64.