THE GEOLOGY OF THE BUNKER HILL MINE

The Bunker Hill Mine is located within the prolific Coeur d’Alene silver belt district. The mine has produced more than 165 million ounces of silver and 5 million tons of base metals over nearly 100 years. Gulf Resources was the last major owner of the mine who closed operations in 1981.

It is hosted in the Belt Supergroup, specifically the St. Regis and Revett units. The district has undergone several folding and faulting events to arrive at where our deposits are located today. The mineralization seems to have occurred at two different times. There are two main styles of mineralization, veins and disseminated.

Understanding the structure of the district is important. The major faults tend to offset mineralization while the minor faults tend to open up the ground for fluid flow. The mineralizing fluids prefer the quartzites of the St. Regis and Revett units.

The Newgard area mineralization was recognized to be strata bound, which is a little different than other known styles of mineralization at the Bunker Hill mine. Large scale folding has occurred to reorient the beds and often are classified as parasitic folds. The Newgard orebody is one of these parasitic folds that will be the starting point for the next mining phase at the Bunker Hill Mine in Q4 2024. The parasitic folds of the Newgard orebody were recognized once the 3D model was build.

The main minerals of interest are galena, sphalerite, and tetrahedrite. There appears to be two mineralization events, one for the lead/zinc and a second for the silver. Tetrahedrite occurs with the galena and in parts of the mine with very little galena. There are several recognized styles of mineralization at the mine and each style is classified based on orientation, lithology and structure.

The exploration potential at the mine is enormous. Over 95 years of mylar plan and section maps were used to build the first digitized geologic model in 2020. Being able to put the data into 3D has significantly increased the geological understanding of the deposit. With the use of 3D models there are areas along several known mineralization trends that have little to no drilling. The trends are open in all directions to mineralization. The current focus is working above the flooded workings but eventually, the dewatering will continue to access new drill platforms to explore the deeper extents of the mine.