The Jim May Garnet occurrence is located near the headwaters of Jim May Creek, about 51 kilometres northwest of the community of Germansen Landing.

Sedimentary and metasedimentary strata of Hadrynian age, of the Ingenika and Misinchinka groups, underlie much of the Aiken Lake-Mesilinka River area (Geological Survey of Canada Memoir 274). Ingenika Group strata outcrop west of the Rocky Mountain Trench and include amphibolite facies rocks which were previously assigned to the Tenakihi Group (Geological Survey of Canada Memoir 274) and migmatites of the Wolverine Complex.

At the Jim May Garnet showing, near Jim May Creek in the Tenakihi Range, Neoproterozoic Swannell Formation (Ingenika Group) rocks (probably pelitic schists) are exposed in an anticlinorium and locally contain abundant garnet and kyanite. Garnets are by far the most common porphyroblasts developed. Approximately 2000 metres of strata occur, in which garnets are reported to comprise as much as 50 per cent of the rock volume (Geological Survey of Canada Memoir 274). The garnets may be up to 2.5 centimetres in size, but are more commonly 1 to 3 millimetres in diameter. A few hundred metres stratigraphically above the garnet-rich strata, pelitic layers locally contain approximately 10 per cent kyanite in crystals which are up to 7.5 centimetres in length (Geological Survey of Canada Memoir 274). Minor amounts of sillimanite are present in the lowest stratigraphic units exposed in the Jim May Creek area.