Final answer:
During the gold rush in California, miners used mercury to extract gold and unintentionally caused environmental pollution. The amount of mercury left in the environment was nearly three times the amount of gold extracted.
Step-by-step explanation:
During the gold rush in California, miners used a technique called amalgamation to extract gold from the stream. This involved adding mercury to their pans, which would collect the gold into an amalgam. However, over time, small amounts of mercury were lost, leading to environmental pollution. The amount of mercury left in the environment was nearly three times the amount of gold that was extracted.