For over a century, the mines of Silver Valley in the Coeur d’Alene Mountains in northern Idaho have been a source of tremendous mineral wealth.
From the mid-1880s, those mines have yielded almost 10 million tonnes of zinc, lead and silver.
The region’s most famous mine, Bunker Hill, was first discovered in 1885 by Noah Kellogg. (In 1894, the nearby Milo prospecting camp was renamed in his honour, eventually leading to the establishment of Kellogg city.)
Between 1887 and 1981, Bunker Hill was one of the most productive mines in America. The mine and its associated electrolytic zinc processing plant and lead smelter produced over 35 million tonnes of ore concentrate, with an average grade of 8.67% lead, 3.67% zinc, and 171.56 grams silver per tonne, including 165 million oz. silver as a by-product.
However, the mine closed in 1981 due to a combination of low base metal prices and the cost of upgrading its processing and smelting operations to meet new environmental regulations introduced by the U.S. Environmental Protection Agency (EPA).
Continue reading at www.northernminer.com.