The Joy showing lies within the Cariboo Terrane of the Omineca Belt underlain by rocks of the Cariboo Group, Cunningham Formation. The Pleasant Valley Thrust, a major thrust fault which marks the division between the Cariboo and Barkerville terranes, lies about five kilometres to the west of the showing.

The Cunningham Formation is characterized by limestone, dolo- stone and fine-grained marble in gradational contact with the under- lying, dominantly clastic, rocks of the Isaac Formation and the over- lying clastic Yankee Belle Formation. These three formations are considered to be Hadrynian (Upper Proterozoic) in age.

Mineralization consists of galena, sphalerite and minor chalco- pyrite within quartz-barite veins hosted by thin-bedded limestone.