The Rosemont past-producing mine is located north of St. John Creek, approximately 9.5 kilometres northeast of Carmi.
The area occurs at a contact zone between metasediments of the Carboniferous-Permian Anarchist Group and quartz diorite of an unnamed Middle Jurassic intrusion. This intrusion was previously mapped as part of the Middle Jurassic Nelson Intrusions (Geological Survey of Canada Map 1736A). Contact metamorphism of the sediments and assimilation of country rock by the intrusives is common. Narrow contact zones are mineralized with 1 to 3 per cent pyrite and pyrrhotite.
Locally, mineralization occurs in quartz as mesothermal fracture fillings at the Anarchist-intrusive contact zone. Pyrite and pyrrhotite blebs and aggregates are found in the 2 to 40-centimetre-thick quartz veins that cut irregularly through small shear zones and the contact fracture zone. Gold is associated with pyrite and chalcopyrite.
In 1980, a select sample of mineralized quartz vein material assayed 16.0 grams per tonne gold, while the following year a sample from a shaft assayed 25.0 grams per tonne gold (Property File - Zygote Resources Ltd. [1988-02-17]: A Report on the Auriferous Property).
During 1937 through 1941, the mine produced 107 tonnes of ore from which 1462 grams of gold and 1928 grams of silver were recovered.
This area was an active exploration camp at the turn of the century, when the Highland Bell (MINFILE 082ESW030) silver mine was discovered. Early references to this general area are to the Knob Hill (MINFILE 082ENW047) occurrence where a 12-metre shaft was sunk in an "iron cap" in 1901.
The Rosemont mine began production in 1937 and closed in 1941. Highland Bell, who operated the mine in 1940 and 1941, carried out approximately 25 metres of drifting and 30 metres of crosscutting during this period, extending the total length of underground workings to approximately 122 metres.
In 1973, Austro-Can Exploration Limited had a VLF-EM geophysical survey carried out over the area that identified anomalies near the old workings. In 1974, prospector H.O. Plank drilled two diamond -drill holes, totalling 26 metres. No assays were recorded. Bulldozer trenching predates the above programs and is thought to have been carried out in the 1960s. In 1981, Cominco staked the property and carried out a soil geochemical survey. In 1984, M.S. Morrison carried out a VLF-EM survey. Three strong north west-trending anomalies were discovered. The claims were allowed to lapse but were re-staked in 1985. In 1986, a biogeochemical survey was carried out by Morrison that identified anomalous zones of silver, arsenic, iron, lead, and zinc coincident with the Rosemont workings and extending to the north west. The property was optioned by Zygote Resources Ltd. in 1987. They funded geological mapping, VLF-EM and magnetometer surveys and biogeochemical surveys. Although anomalous zones were identified, the property was allowed to lapse. It was re-staked in 1989 by Morrison who carried out another biogeochemical survey in 1990. A cadmium anomaly was discovered that coincides with previously identified VLF-EM anomalies. In 1993, Richard H. Lonsdale acquired the Rosemont Crown grant and conducted sampling.