The Johnny Lee deposit at Black Butte is named for a homesteader/prospector who lived above the deposit in the early 1900s. The mineral deposit includes two sheet-like zones rich in extremely high-grade copper ore contained in a copper-iron-sulfide mineral (chalcopyrite). It is one of the highest-grade copper deposits currently under development in the world. In fact, it is more than 10 times higher in copper concentration than copper deposits mined by modern surface mining methods.

Although there are active fault zones in Montana, the fault closest to the deposit called the Volcano Valley Fault is dormant. This is a major fault zone passing between the upper and lower zones of the Johnny Lee deposit. Current geologic interpretations indicate that this fault is long dormant (80 million years) and poses no threat to the mining operation or environment.

The 1.4-billion-year-old deposit formed on the seafloor around hot springs system similar to the “black smoker” type known on today’s ocean floors. In the ancient sea bottom hot springs at Black Butte, hot water with high concentrations of dissolved metals and sulfur vented onto the seafloor and encountered very cold seawater. The change in temperature and chemistry caused the metallic elements including copper to bond with other elements including sulfur and precipitate onto the seafloor as metal-bearing sulfide minerals. The precipitated minerals built up into sheet-like layers later buried under thousands of feet of sediment. After formation of the Rocky Mountains, erosion exposed the deposits near the earth’s surface so that they can be mined.

Located completely on private land, our underground mine will have an extremely small footprint above and below ground. The underground workings contain approximately 14.5 million tons of copper-enriched rock encompassed in an area of 3,000 feet by 2,000 feet. The surface disturbance of the mine workings is planned for a footprint of 310 acres, within an overall permit boundary of 1,888 acres. A four-wire fence will surround the surface facilities which include the 80 acre cemented tailings facility, 20 acre process water pond, roads, parking areas, plant facilities, and the temporary waste rock storage areas. A tall wildlife protection fence will surround each pond and the dry cemented tailings facility.