The Jumbo claim, located about 3.2 kilometres northwest of Rossland, was staked by A.D. Coplen in 1892 and Crown granted to J.A. Finch & associates in 1895. The Jumbo Gold Mining Company of Spokane operated the mine from 1896 until it closed in 1906. Development work, totalling over 244 metres of tunnel was carried on in three adits. Further work was done on the property during 1934-36 by Mr. Slubowski and associates. Lessees worked the property, owned by Mrs. C.F. Smith of California, during 1942.

Late in 1963 Torwest Resources (1962) Limited acquired a group of 10 claims, including the Jumbo and Coxey. Some diamond drill holes were put down on the presumed extension of the oreshoot on the Jumbo. (See: Coxey; Area, 82F/4, Ref. Mo 1).

The Jumbo Crown Grant is underlain by siltstone, hornfelsed siltstone, hornfels and a breccia complex of the Pennsylvanian and possibly Permian Mount Roberts Formation. The siltstone is rusty, sooty and massive or thinly bedded with minor disseminated pyrrhotite and pyrite. The hornfels and hornfelsic siltstones are thinly laminated, massive cherty rocks, which locally contain brown garnet and epidote.

The succession is thought to have been thrust over augite porphyry of the underlying Rossland sill of the Elise Formation (Rossland Group) prior to the intrusion of the Middle to Late Jurassic Trail pluton (Nelson Intrusions). The siltstone is also intruded by the Early Jurassic Rossland monzonite and monzonite breccia as well as by the syenitic Middle Eocene Coryell Intrusions and associated syenite dykes. Lenticular masses of andesite and late, steeply dipping, north-trending lamprophyre and diorite dykes have also invaded the siltstone.

A vein along a minor shear, ranging up to 9 metres or more in width, is mineralized with pyrrhotite, arsenopyrite, molybdenite, bismuthinite and native gold in a gangue comprised mainly of quartz with ankerite and calcite. The gold values were highest where the vein is crosscut by syenite dykes. The bismuthinite occurs in particles or aggregates up to a few centimetres in diameter and usually shows perfect cleavage with a lustre that is intermediate between lead-grey and tin-white. Pyrrhotite and other sulphides are associated with the native bismuth and bismuthinite in the country rock. It is often seen as a thin film along cracks and fractures. Visible free gold is frequently found with native bismuth.

Between 1903 to 1906, 28,829 tonnes of ore was mined and produced 415,878 grams of gold. And, between 1934 to 1942, approximately 1965 tonnes were mined and produced 19,719 grams gold and 12,347 grams silver.

The molybdenum mineralization occurs within the breccia complex which is comprised of angular blocks of siltstone and hornfelsic siltstone ranging up to 30 metres across. Molybdenite occurs in randomly oriented fractures in the breccia and locally, is concentrated at the junctions between the blocks. Pyrrhotite, pyrite and minor chalcopyrite with arsenopyrite also occur within fractures in the breccia and as massive lenses between the fragments. Magnetite is found in the ore as microscopic particles associated with the arsenopyrite-molybdenite. The magnetite adjoins or surrounds the arsenopyrite grains with a thin rim or coating. Hematite is represented only by pseudomorphs of magnetite.

Molybdenite occurrences are spatially related to the the Middle to Late Jurassic Trail pluton, especially its upper and western margins. In the region, both skarn and porphyry molybdenum mineralization occur along the margins of the Nelson Intrusions (Fieldwork 1990, pages 21-31). The characteristics of the molybdenite mineralization on Red Mountain indicate classification as a porphyry-type deposit (Bulletin 74, page 52). The copper-gold vein-type mineralization is apparently younger than the porphyry/skarn events.