The Sunshine Mountain chromite prospect is on the west spur of Sunshine Mountain between Noel and Craxy creeks and is within the "Pioneer Ultramafite" of Wright (1974) (part of the President Ultramafics which are correlative with the Permian and older Shulaps Ultramafic Complex). These units consist of well layered harzburgite, dunite, orthopyroxenite, olivine orthopyroxenite and serpentinite; all ultramafic rocks are serpentinized to some degree, contain chlorite and are limonitic on weathered surface (a characteristic rusty appearance due to limonite). They are knobby surfaced due to orthopyroxene being more resistant to weathering. Adjacent to the ultramafic body, on the west, is chert of the Mississippian to Jurassic Bridge River Complex (Group) and, on the east, clastic sedimentary rocks of the Upper Triassic Hurley Formation (Cadwallader Group).

The chromitite concentrations are stratiform layered to lens- shaped bodies composed of up to 85 per cent chromite with interstitial orthopyroxene (enstatite) and serpentine minerals. Individual chromite grains are 1 to 15 millimetres in size, rather equant in shape and form a slight mega-cumulate texture. Chromite concentrations range from a few centimetres in thickness, continuous along layering for several centimetres, up to approximately 10 centimetres in thickness and continuous along strike for approximately 200 centimetres. Chromatite layers bifurcate in places (rare). Nearby, layered harzburgite has disturbed layering - possibly due to turbulence within the still molten ultramafic magma chamber.