The Yellow Creek occurrence is located at the head waters of Yellow Creek on the west side of McNaughton Lake, approximately 13 kilometres south-southeast of Boat Encampment. Warsaw Mountain is located approximately 3.25 kilometres to the northwest.

Mineralization at the Yellow Creek occurrence consists of two types: kyanite and mica hosted in schists and gneiss, and mica and beryl hosted in pegmatite sills and dykes.

The area is underlain primarily by folded metasedimentary rocks of the Hadrynian Horsethief Creek Group. The regional foliation in the area strikes 294 degrees and dips 66 degrees. Upper amphibolite facies metamorphic conditions were reached in the northern Monashee Mountains at circa 100 Ma (Geology Vol. 18, pp. 103-106). An expanded description of the regional geology is given in the Warsaw Mountain showing (083D 041).

At the Yellow Creek occurrence, kyanite is present near the base of the Semipelite-Amphibolite unit (Geological Society of America Memoir 153) or equivalent Aluminous Pelite unit, both of the Horsethief Creek Group (Open File 1988-26). A recent regional compilation, however, shows these lithologies as belonging to the underlying Lower Pelite unit of the Horsethief Creek Group (Geological Survey of Canada Open File 2324).

Kyanite is found mainly in schists and coarse gneisses with muscovite, biotite, quartz, feldspar and garnet. Greyish-blue flat kyanite crystals vary in size from place to place, ranging from 0.6 to 7.0 centimetres long. Kyanite comprises up to 10 to 15 per cent by volume of the rock in the area.

A micaceous pegmatite sill is exposed at about 1524 metres elevation over approximately 45 metres. Muscovite comprises 15 per cent per rock volume in isolated patches, generally averaging much less. A second pegmatite sill, 1.5 to 6.0 metres thick is exposed at 1951 metres and intrudes schist and gneiss. Muscovite averages approximately 10 per cent rock volume, reaching as high as 20 per cent over 3 square metres. Individual muscovite booklets reach a maximum of 20 centimetres diameter and 5 centimetres thick, the average being much smaller. Most of the muscovite is twinned, badly cracked and iron stained. Nearby exposures of pegmatite contain minor amounts of tourmaline (Watson, 1944).

A beryl crystal was observed at the locality of the pegmatite mentioned above (ibid.). Beryl was reported seen in pegmatites at the Head of Yellow Creek. Spectrographic analyses recorded trace beryllium in muscovite and biotite from pegmatite and in kyanite and garnet from the wall rock schist (American Mineralogist, Vol. 18, p. 94, 1947).