The Jumbo occurrence is located 3.5 kilometres north of Toby Creek in the Golden Mining Division. The occurrence is on the south flank of Monument Peak at 1900 metres elevation above sea level.

Regionally, the area is underlain by Proterozoic clastic sedimentary rocks of the Purcell and Windermere supergroups and by lower Paleozoic strata of the Beaverfoot and Mount Forster formations (Geoscience Map 1995-1).

The Purcell Supergroup strata include the Aldridge, Creston, Kitchener, Dutch Creek and Mount Nelson formations. The Windermere Supergroup unconformably overlies the Purcell Supergroup rocks and includes the Toby Formation and Horsethief Creek Group (Paper 1990-1).

In the vicinity of the occurrence, rocks of the Kitchener and Dutch Creek formations have been further subdivided and assigned to the Van Creek and Gateway formations. The Van Creek Formation correlates with the Lower Kitchener Formation while the Gateway Formation is equivalent to the lower portion of the Dutch Creek Formation. The Mount Nelson Formation has been subdivided into seven discrete members, a lower quartzite, a lower dolomite, a middle dolomite, a purple dolomite, an upper middle dolomite, an upper quartzite, and an upper dolomite (Open File 1990-26).

Rocks of the Horsethief Creek Group, Beaverfoot and Mount Forster formations are folded and overthrusted by rocks of the upper portion of the Dutch Creek Formation and the lower members of the Mount Nelson Formation. The sedimentary rocks have undergone regional metamorphism to at least greenschist facies.

The occurrence is hosted within dolomite of the Gateway Formation and comprises galena, sphalerite, pyrite and minor bournonite as replacement. Mineralization is believed to be of similar character to that found at the Mineral King (082KSE001) (Geology, Exploration and Mining in British Columbia 1971).

In 1970, a plant was installed on the property to recover barite from the old tailings pond of the Mineral King mine. For records of this production please see 082KSE001.