Modern bulk methods for processing metal ore, particularly precious metal ore, often use liquid cyanide compounds to precipitate out small traces of the metal from huge piles of ore. It's cheap, it's relatively easy to set up, and it can be deadly if the cyanide leaks out of what is called the leach pad.
In 1998 Montana voters passed a proposal that banned the use of cyanide in mining. The owners of a huge and highly lucrative gold deposit sued the state for the loss of value of their property. That suit is still pending. But, this year those owners also got a proposal on the Montana ballot that would have overturned the cyanide ban. That proposal was rejected 58 to 42 percent.
(Comments are open to all. After clicking on "Comments," click on "Or Post Anonymously" if you don't have an account.)