The 72K showing is located southeast of the Craig River, approximately 8 kilometres southwest of its junction with the Jekill River.
The area is underlain by a sequence of metamorphosed Upper Paleozoic rock of the Stikine Assemblage consisting of sediments and volcanics comprised mainly of argillite, chert, quartzite, slate, shale, schist, minor limestone and tuff. The Paleozoic rocks are unconformably overlain by rocks of the Upper Triassic Stuhini Group and the Lower Jurassic Hazelton Group. The stratigraphy is intruded by Late Triassic dioritic and quartz monzonitic plutons, Lower Jurasssic monzodioritic to gabbroic plutons and Eocene plutons (undivided).
72K Creek drainage appears to cut a sequence of shaly metasediments which include black shales and limy metasediments, which locally contain brecciated quartz-carbonate veins and stringers mineralized with pyrite and pyrrhotite. In 1987, two samples collected from these mineralized veins assayed 0.02 gram per tonne gold, 1.2 grams per tonne silver, 0.012 per cent copper, 0.01 per cent zinc and 0.02 grams per tonne gold, 0.9 gram per tonne silver, 0.096 per cent copper with 0.01 per cent zinc (Assessment Report 16620, Figure 4).
In 1983, a large area between the Craig and Jekill rivers was covered by Star 1-8 and 10 claims and was explored by Energex Minerals Ltd, who collected 31 rock, 44 silt and 26 heavy mineral concentrate samples. The company identified several significant gold anomalies in heavy sediment samples. Values ranged from 3000 to 72,000 parts per billion Au in several creeks draining into the Craig River from the south (Assessment Report 11342).
In 1987, operator Tanker Oil and Gas Limited conducted a prospecting and geological work program on the Zeehan 8-14 claims that resulted in the collection of 31 heavy mineral concentrate, 90 silt, 169 soil and 160 rock samples. The owner of the property was Skyline Explorations Ltd. The Zeehan claims covered much of the western and northern parts of the ground previously covered by the Star claims in 1983.
In 1989 Skyline Explorations Ltd collected a total of 428 contour soil samples, 3 stream silt samples, 15 rock samples and 16 heavy mineral samples from the Zeehan 10, 12 and 13 claims east of the Craig River. The contour soil lines ran from N6 Creek in the northeast to 72K Creek in southwest (Figure 7a, Assessment Report 19366). The widely spaced contour soil lines covered the drainages where documented MINFILE occurrences exist which include: Pyrite Creek (104B 266), Log Jam Creek (104B 265), N2 (104B 267), 72k (104B 304). Prospecting with geological evaluation occurred on known mineral occurrences on the Zeehan 10, 12 and 13 claims.