The Jay occurrence consists of a minor copper showing in mountainous terrain 5 kilometres south of the southern end of Knot Lakes, just south of Tweedsmuir Provincial Park.

The occurrence is located in a unit of metavolcanic rocks in the Gambier overlap assemblage near the northeastern margin of the Jurassic to Tertiary Coast Plutonic Complex (Geological Survey of Canada Open File 1163, Map 1713A). Very little information is available on the mineralization, or even on its precise location (Geology, Exploration and Mining in British Columbia 1969).

In 1969, American Smelting and Refining Company conducted a geological survey and a geochemical survey comprising 50 silt samples on the Jay 1 to 49 claims.

Chalcopyrite occurs as a replacement in chloritized metasedimentary rocks.