The Teditua Creek showing is hosted by the Upper Mississippian to Permian Nahlin ultramafic body, part of the Cache Creek Complex. The Nahlin body is 100 kilometres long and up to 8 kilometres wide and is the largest alpine-type ultramafic in the Canadian Cordillera. On the southwest it is faulted against Lower Jurassic sedimentary rocks (Inklin Formation, Laberge Group, and Upper Triassic Stuhini Group volcanic rocks) and on the northeast against Upper Paleozoic rocks of the Cache Creek Complex.

The ultramafic body typically consists of hard, dark green to black peridotite with crystals and crystal clusters of pyroxene, ranging from 0.3 to 1.3 centimetres across. The principal variation in the body is the degree of serpentinization, which is most intense along contacts and sheared or brecciated zones.

Exposed contacts between the Nahlin ultramafic body and layered Jurassic and Triassic rocks are invariably marked by fault zones adjacent to which the peridotite has been sheared and serpentinized. The Nahlin fault, which bounds the southwestern margin of the body, comprises a subparallel network of anastomosing shear planes and fractures with steep north or vertical dips.

Locally, the highly serpentinized rock contains a filigree of fine chrysotile veinlets usually less than 1 millimetre across. An asbestos occurrence is located along the Nahlin fault as shown on GSC Map 1262A. The thicker chrysotile veins, ranging up to 2 centimetres across, apparently contain brittle slip-fibre that are deemed as of no commercial value.

Adjacent to this major fault network the serpentinized peridotite has also been carbonatized (listwanite). Ankerite is the principal carbonate but veins of pure white, microgranular magnesite and coarsely crystalline dolomite are also present. Where serpentinization is complete, veinlets of antigorite blades with disseminated magnetite grains also occur.