The Jack of Hearts occurrence is described as being located on Twenty Mile Mountain, which does not occur on modern maps but should be northeast of Eighteen Mile Creek, 25 kilometres east of Hazelton. Geological Survey of Canada Open File 2322 shows an occurrence (#242) in this same area, on the southeast side of Natlan Peak. These are likely the same showing.

Lithologies in the area comprise argillites and greywackes of the Middle Jurassic to Lower Cretaceous Bowser Lake Group. A diorite to granodiorite plug of the Late Cretaceous Bulkley Intrusions outcrops west of the reported location of the occurrence.

The occurrence is described as a 45-centimetre seam of sphalerite, with thin bands of greyish white magnesian ankerite and minor galena. The seam occurs in a quartz gangue and appears to follow a bedding plane in altered sedimentary rocks. The sedimentary rocks strike 030 degrees, dipping 50 degrees northwest. The footwall consists of rusty argillite and the hangingwall of hard silicified sandstone.