The Ice River valley is situated in Yoho National Park in the westerly ranges of the southern Rocky Mountains, British Columbia. The region is the site of a nepheline syenite-ijolite-jacupirangite complex which is intruded into Cambro-Ordovician sediments and is dated (potassium-argon method with biotite) as Devonian in age.

Associated with the ijolite-jacupirangite differentiates is a mass of brown-weathering carbonate (dominantly iron carbonate with calcite and iron oxide) at least 2 miles long and 900 feet across. This mass was originally described as a "stoped block or roof pendant" but recent field observation indicates that the carbonate is intrusive. Two traverses are described.

The carbonate is succeeded by an intensely fractured and brecciated ferruginous zone, which merges into carbonatized aegirine-feldspar gneisses which in turn merge into and alternate with ijolite or the aegirine-feldspar pegmatite dykes that cut the ijolite. Augen of unaltered to partly altered pegmatite occur commonly in the gneiss. Pods and lenses of carbonate (similar in composition to that of the main mass and as much as 500 feet from it) are associated with the gneiss.

A 10-foot zenolith of aegirine-feldspar pegmatite occurs in the main mass of carbonate. Toward the periphery of the zenolith the pegmatite merges into gneiss, then gneiss with carbonate and finally carbonate.

The carbonate mass may be termed carbonatite.

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