The Jumbo prospect is located 4 kilometres north-northwest of Vernon, between Swan and Okanagan Lakes.

In this area, west of the Okanagan Valley fault zone, volcanic and sedimentary rocks of the Devonian to Triassic Harper Ranch Group are unconformably overlain by Upper Triassic to Lower Jurassic Nicola Group sedimentary and volcanic rocks. These units are intruded by Middle Jurassic granitic rocks. Patches of Eocene Penticton Group volcanic rocks underlie the older rocks.

Quartz veins and veinlets in Nicola volcanic rocks, adjacent to argillites, host gold and silver mineralization. A series of north- south stringers is cut by an east-west vein. This irregular drusy vein is fractured and faulted, up to 1.2 metres thick and traceable for 20 metres. The vein carries disseminated free gold and sparse to heavy pyrite mineralization. Native sulphur is reported as a weathering product of pyrite. The vein contains erratic grades; the best values are 93 grams per tonne gold and 10 grams per tonne silver (Minister of Mines Annual Report 1930, page 208).

The first reference to the occurrence is from 1897. In 1929, a 3.5 metre shaft was sunk and a short crosscut driven. In 1940, a 49- tonne shipment produced 373 grams of silver and 342 grams of gold.