A Canadian-owned mine in northern Mexico spilled over a half-million gallons of a cyanide solution used in heap-leach gold mining, after heavy rains caused a retaining pond to overflow.
The accident occurred at the Proyecto Magistral mine in the northern state of Durango. The mine is owned by a subsidiary of Toronto, Canada-based McEwen Mining Inc.
The Attorney General for Environmental Protection said Wednesday that the cyanide-laced solution contaminated an area of about a half-kilometer (quarter mile).
The office ordered the company to install membranes in holding ponds and raise the height of containment dams.
It was the second mine spill in as many weeks in Mexico. Earlier this month, a mine in Sonora state spilled 10 million gallons (40,000 cubic meters) of mining acids into a river. It is suspected that the spill included a mix of cyanide, the mine company disputes the use of any cyanide at their mines.