Block-cave mining, implemented at Climax Mine in 1927, was one of the most significant technological advances in the mine’s history. It cut the production cost of molybdenum in half and kept the mine open and profitable through the Great Depression. “Big Shots” were central to this method, with explosives placed at carefully calculated points throughout the orebody and detonated all at once so the fractured rock would gradually collapse under its own weight. The most memorable Big Shot at Climax came in 1964, when more than 2,000 tons of explosives were set off in the largest underground blast in mining history. On that warm spring day, Colorado 91 was closed and Climax employees lined the highway with picnic lunches as they watched a section of Bartlett Mountain a quarter-mile wide and 1,000 feet high collapse into the Glory Hole. With most of the orebody now exposed, mining has shifted toward gathering ore from the surface with excavators and haulage trucks, though some underground ore still remains.
