The Foster's Ledge occurrence is located on the north side of the San Juan River, near the junction of Williams Creek and the river.
The area is underlain by deformed metasediments, schist, shale, wacke and siltstone of the Jurassic to Cretaceous Leech River Complex.
Mineralization identified comprises pyrrhotite, both disseminated and along fractures. The mineralization is similar to that developed at Valentine Mountain (092B 108) to the southeast.
The Foster's Ledge claim was located in 2000 and covers several creek outcrops showing irregular quartz veining and boudinaged quartz veins.