The Cadwallader Creek talc showing occurs in sediments of the Mississippian to Jurassic Bridge River Complex (Group) consisting of chert and argillite. Serpentinite of the President Ultramafics, which are thought to be correlative with the Permian and older Shulaps Ultramafic Complex, also occur.

Generally, the talc is associated with approximately equal amounts of ankerite and contains serpentine, disseminated sulphides (mostly pyrite), magnetite and chromite. The colour varies from creamy white to dark reddish purple. The believed source of the altering thermal solutions are the late siliceous differentiates of the nearby Permian Bralorne Igneous Complex or, less likely, the Cretaceous to Tertiary Bendor pluton.

In the Pioneer Extension workings, a shaft cuts through 30 metres of highly talcose rock lying beneath an albitic dyke. Nodules of Bridge River chert and argillite are found within the talc bed. It has been suggested that this particular showing of talc may not be derived from serpentinite but directly from the metasediments. Magnesium, necessary for this transformation, could have been supplied from the nearby Bralorne gabbros and diorites or from late solutions emanating from the ultramafic bodies themselves. Analysis of the talc in 1937 yielded the following results (in per cent) (Geological Survey of Canada Memoir 213, page 71):

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Silica                           58.40
Ferric Iron (+ minor alumina)     8.07
Magnesia                         29.66
Water (by difference)             3.87
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A 30-metre-wide zone of talc rock is also found on the north border of a serpentinite belt separating the altered ultramafics from soda-granite. Albitite dykes intrude the talcose zones.