The Bronco occurrence is located at an elevation of approximately 1400 metres on an east-southeast–facing slope, west of Hellroaring Creek and approximately 4 kilometres south of St. Mary Lake.

Regionally, the area is underlain by argillite, greywacke, wacke, conglomerate turbidite and quartzite of the Mesoproterozoic Aldridge Formation (Purcell Supergroup) cut by numerous sills of the Mesoproterozoic Moyie Intrusions and pegmatite. To the east, granodioritic intrusive rocks of the Mesoproterozoic Hellroaring Creek Stock are exposed.

Locally, two zones of coarse-grained galena and sphalerite are associated with quartz in a fractured and silicified quartzite adjacent to a major regional fault. The zone strikes 300 degrees with a dip of 20 degrees. Reports indicate that this zone is likely the northwest extension of the mineralized zones exposed on the Warhorse (L.13077; MINFILE 082FNE061) occurrence to the southeast.

Later work in the area, in 2024, identified pegmatites hosting anomalous values of beryllium, rubidium and tin to the north of the occurrence.

Work History

In 1971, Kerr Addison Mines Ltd. conducted a regional program of geological mapping and geochemical (soil and silt) sampling on the are as part of the Dewar Creek project.

In 1980, Lacana Mining Corp. conducted a program of soil sampling and a 9.0 line-kilometre ground magnetic survey on the area as the Forson claims of the Bronco property. A chip sample assayed 1.2 per cent lead, 0.45 per cent zinc and 35.7 grams per tonne silver over approximately 1.8 metres (Assessment Report 8466).

In 1983, Noranda Mining and Exploration Inc. conducted an airborne magnetic and electromagnetic survey on the area as part of the Mount Evans property. In 1987, Esso Resources Canada Ltd. conducted a program of geological mapping, geochemical (rock and silt) sampling on the area as the Mac 1-10 claims.

In 1991 and 1992, Minnova, in conjunction with Kokanee Explorations, completed a regional program of prospecting, geological mapping, geochemical (rock and soil) sampling and a 12.0 line-kilometre electromagnetic survey on the area immediately north as the Horn and Darlin claims.

In 2024, a program of prospecting, geological mapping and geochemical (rock and soil) sampling was conducted by Giacomo Grassi on the area as the Gem Hunter claim. Rock samples (JKGHR008 through JKGHR010, BRGHR001, MHGHR003 and ACGHR015) of pegmatites, located approximately 250 to 900 metres to the north of the occurrence, yielded values from 0.015 to 0.056 per cent beryllium, 0.020 to 0.100 per cent rubidium and 0.003 to 0.018 per cent tin, and two nearby samples (ACGHR005 and ACGHR006) of silicified siltstone yielded 0.015 and 0.021 per cent lithium, respectively (Assessment Report 42322).