In its more than a century-long career, Coeur d’Alene has earned the distinction of one of the world’s largest silver-zinc-lead producing districts and has birthed a number of world-class mines; including Lucky Friday, Galena, Sunshine as well as Bunker Hill-the oldest and largest producer in the Silver Valley.
Today, resource companies are still exploring and developing projects in the region, creating further opportunities for investors.
This INNspired Article is brought to you by:
Bunker Hill Mining. (CSE:BNKR) is implementing an ambitious plan to re-commission one of the largest silver-lead-zinc mines in the Americas not in production.Send me an Investor Kit
Large tonnage, long mine life deposits in Idaho’s Panhandle
The Coeur d’Alene mining district is seated near the base of Idaho’s northern Panhandle region, and within the Coeur d’Alene Mountains. The district owes its genesis not to silver but to gold, first discovered in the North Fork of the Coeur d’Alene River in 1881. Noah Kellogg’s famed Bunker Hill discovery would follow a few year later.
Coeur d’Alene’s geology is characterized by large ore bodies that occur in long, steeply dipping narrow veins ranging from centimeters to several meters in width that can also extend to great depths of one mile or more below surface. The majority of these ore-bearing veins are associated with a the Osburn fault, a major structural feature that extends the length of the Silver Valley. Most veins are found in one of three stratigraphic horizons, which can determine the mineral composition and deposit type: the Prichard Formation near the middle quartzite hosts primarily zinc-rich deposits; the Prichard Burke transition zone hosts lead-zinc-rich deposits; and the Revett St. Regis transition zone hosts lead-silver-copper-rich deposits.
After geology laid the fuse, enterprise and geography together lit the spark that would spur breakneck growth in the district. The Northern Pacific Railroad lured passengers aboard with the promise of gold to be found in northern Idaho-bringing in a rush of prospectors and mine labor. The district sits in the South Fork the Coeur d’Alene River, considered the highest navigable river in the world-allowing for the easy transport of ore.
By the 1970s, zinc, lead and copper production were in full swing in the Coeur d’Alene district and nearly half of US silver production occurred in Coeur d’Alene. Today, the district has produced well over 1.2 billion troy ounces of silver, more than 3.3 million tonnes of zinc and more than 8 million tonnes of lead.
Bunker Hill, a major player in US zinc history
The Coeur d’Alene’s most famous mine, Bunker Hill was first discovered in 1885 by Noah Kellogg-the region’s first major deposit discovery. Eventually, Bunker Hill would come to include several deposits with a mill, smelter and lead-zinc refineries combined into one large complex.“Bunker Hill was instrumental in developing uses for zinc and contributed much to the zinc die-casting industry,” according to the Idaho Geological Survey.
Between 1887 and 1981 the mine produced 35.9 million tonnes of ore, with lead grades of 8.76 percent, 3.76 percent zinc and 4.53 ounces per ton silver. Prior to its closure in 1981, the mine complex was responsible for 20 percent of US refined lead and zinc production and 25 percent of silver.
Today’s Coeur d’Alene
Hecla Mining’s (NYSE:HL) Lucky Friday silver-zinc-lead mine has been in operation since 1942 and is strong model for production potential of other deposits in the district. In recent years, Hecla has increased the mine life of the Lucky Friday by another 20 to 30 years with the acquisition of the Lucky Friday Expansion area in 2008 and the 2016 completion of the 9,600 foot #4 Shaft, the deepest mine shaft in all of the United States. In 2