The Black Bear ore is part of the "Main vein" system, of the Rossland mining camp, which forms a continuous well defined fracture system on a regional scale. The system strikes about 070 degrees for a length in excess of 1.0 kilometre. The Black Bear ore shoot was mined as part of the Le Roi deposit which produced from 1893 to 1942. Refer to the Le Roi deposit (082FSW093) for further details.
The Black Bear vein is hosted by the Lower Jurassic Rossland Group (Elise Formation) augite porphyry, known as the Rossland sill, and by the Early Jurassic Rossland monzonite Intrusive which is comprised of a biotite-hornblende-augite monzonite stock that intrudes the sill. A Tertiary lamprophyre dyke trending north 10 to 20 degrees west crosscuts the monzonite and the sill. The dyke, referred to as the Josie dyke, averages more than 20 metres in thickness. The Black Bear ore shoot has been faulted approximately 100 metres south along the Josie dyke on the south border of the monzonite stock which is in contact with the augite porphyry.
Mineralization consists of pyrrhotite, chalcopyrite, and minor pyrite which has replaced the wallrock along the well defined fault and infilling the associated fractures. Pyrite occurs as crystals in the pyrrhotite and as disseminations in the host rock. The gangue consists mainly of altered wallrock with minor lenses of quartz and calcite. The ore shoot ends abruptly against the dyke and cross structures.
In 1919, 1,314 tonnes of ore were mined from the Black Bear shoot after the Le Roi mine ceased producing in 1917. Recovery from the ore totalled 5,474 grams gold, 9,891 grams silver, and 4,214 kilograms copper.
The War Eagle mine is part of the "Main vein" system, in system on a regional scale. The vein system occurs on two general strikes of which the better developed is about 070 degrees. The veins have been traced in excess of 1.0 kilometre with veins dipping steeply to the north. The less developed vein system is the War Eagle type which strikes 120 degrees and dips 70 degrees north. The War Eagle system is at best only a series of detached ore shoots with marked stepping to the north. The series of ore shoots have narrow widths and short strike lengths with the greatest dimensions down dip. The ore shoots end abruptly against dykes or cross structures.
The system is hosted by the Rossland monzonite, a biotite- hornblende-augite monzonite stock that intrudes augite porphyry of the Lower Jurassic Elise Formation (Rossland Group), known as the Rossland sill. The porphyry is thought to have been a stock or dyke-like feeder for the sill exposed on the surface, prior to the monzonite intrusion.
The veins were formed by mineralization replacing the wallrock along well defined fractures and by filling fractures and faults with pyrrhotite and chalcopyrite. The gangue consists of altered host rock with minor lenses of quartz and calcite. Grayish banded wollastonite is associated with the ore near the altered host rock and gmelinite has been reported, occurring as reddish-white well-formed crystals. Pyrite occurs as well formed crystals in the pyrrhotite and as disseminations in the host rock. Native gold was reported to occur as disseminated fine specks in rusty patches of quartz-rich ore. Minor molybdenite occurs in quartz-rich veins. A brown to black variety of sphalerite was found cutting vein-like through chalcopyrite and pyrrhotite.
Native silver has been identified in pyrrhotite rich ore in the War Eagle mine. It occurs as blebs along grain contacts of pyrrhotite and at the contacts of pyrrhotite with magnetite and gangue. Small grains of a silver-bearing mineral, probably stromeyerite, which develop a very heavy surface stain are associated with the silver.
Between 1898 to 1905, 300,169 tonnes of ore were mined with recovery totalling: 5,659,751 grams gold, 12,036,613 grams silver and 5,021,436 kilograms copper.
Refer to the Le Roi deposit (082FSW093) for further details of the Rossland mining camp and the Main vein system.
