The Humboldt showing is 1.5 kilometres east of the Similkameen River and 15.5 kilometres south of Princeton.
The area is underlain by the eastern facies of the Upper Triassic Nicola Group, comprising mafic augite and hornblende porphyritic pyroclastics and flows. These rocks are intruded by diorite and monzonite, locally pyroxenite and gabbro, of the Early Jurassic Copper Mountain and Lost Horse intrusions.
This showing is hosted in diorite of the Copper Mountain stock (Copper Mountain Intrusions), about 360 metres southwest of the stock's contact with Nicola Group volcanics.
A shaft exposes a quartz-calcite vein 0.9 to 1.0 metres wide, striking 070 degrees. The vein is mineralized with pyrite and copper sulphides. The diorite is reported to contain chalcopyrite and bornite in the vicinity.
This showing was explored by a shaft, 11 metres deep, and several trenches between 1898 and 1901. Some diamond drilling occurred between 1902 and 1934.