Bornite and Stromeyerite
Bornite is an important copper ore mineral found in many different types of copper deposit. It is also known as peacock ore because of its iridescent purple-blue-green tarnish. Fresh bornite, however, is copper red. Bornite commonly occurs with other copper sulphide minerals such as chalcocite and weathers, or “oxidizes”, to malachite.
Stromeyerite is a copper-silver sulphide mineral. It forms metallic dark grey-blue crystals. It was named after Friedrich Stromeyer, a German chemist, who first analyzed the mineral. Stromeyerite is usually found in veins that contain copper and silver, where silver replaces some of the copper in bornite.
This sample is from the Silver King mine about 7 km south of Nelson in the Kootenay region of southeastern BC.
The Silver King mine was active between 1896 and 1949. In that time, it produced over 200,000 tonnes of ore at grades of 672 grams per tonne silver, 0.5 grams per tonne gold and 3.2% copper. It was once Nelson’s largest mine, putting the town on the map as one of BC’s major silver mining centres. A mining camp, the Silver King Camp, was also home to about 200 people at the mine site, but it was burned down in the early 1900s in a forest fire.
The property was discovered in 1886 by the Hall brothers, who were prospecting for placer gold. They staked three claims: Kootenay Bonanza, Silver Kings and American Flag. The first high-grade ore was shipped in 1889. Initially, ore was transported down the mountain by a process called raw hiding. This was a very dangerous job for the men that transported the ore down! Ore was wrapped in cow hides, hair side down, and attached to a length of rope and pulled down the mountain by horse. A rider sat on the last hide in the train, attempting to control the speed and direction of the hide train using chain brakes. Trails were often icy and extremely slippery, making it very difficult to control the loads. Thankfully a tramway was soon built to transport the ore instead!
In 1893, Hall Mines Limited purchased the property and developed the underground workings and a tramway to transport ore to Nelson for smelting. A 100 tonne-per-day smelter was opened in town in January of 1896. Mining continued until 1919, with small operations in 1936, 1946-1949, 1956 and 1958. Exploration has continued intermittently since then. For several years in the 1960s and early 1970s the slope around the mine hosted a ski hill. The founders of that ski hill eventually went on to establish the Whitewater hill, still open today.
The ore at Silver King is mainly in veins that run parallel to a shear zone, or faulted deformation zone. The veins contain pyrite, chalcopyrite and galena (lead ore), with minor amounts of sphalerite (zinc ore), bornite (copper ore), malachite and azurite (secondary copper minerals), and stromeyerite, as seen in this sample. The main gangue (waste) mineral is quartz, with minor carbonate.
Store: Association for Mineral Exploration (AME)
Accession #: AME 994
Primary Mineral: Bornite & Stromeyerite
Secondary Mineral: –
Site Locality: Silver King Mine
Location: Nelson, British Columbia
Special Features: n/a