By editor
Butte, Silver Bow County
They called Butte "The Richest Hill on Earth." Sixty-six million years ago, hydrothermal fluids deposited a staggering concentration of copper, silver, gold, and zinc. In 1955, miners began tearing the mountain apart from the top down, creating the Berkeley Pit. When mining ceased, groundwater flooded the mile-wide hole. Today, the water in the pit is a toxic soup of heavy metals and sulfuric acid, with a pH of 2.5.
Visitor Access
The Berkeley Pit is an active Superfund site. Collecting is strictly prohibited. However, from May through October, visitors can pay a three-dollar fee to walk through a tunnel to a designated viewing stand suspended over the toxic water—a stark, terrifying monument to industrial scale.