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What geologists have to say about Summitville

Brief by Central Staff

Mining – July 2001 – Colorado Central Magazine

Ever since the Summitville Mine closed in 1992, it’s been often in the news. The open-pit gold mine, at the headwaters of the Alamosa River in Rio Grande County, had already been under state scrutiny for water pollution.

When the mine closed, its owner — Galactic Resources of Canada — filed for bankruptcy after producing $82 million in gold. And now clean-up costs have already exceeded $150 million.

There were all manner of environmental problems. The mine used a cyanide heap leach to treat ore, and cyanide solutions were leaking into the creeks, along with acidic water from other sources.

But not all of the acidic water that reached the Alamosa River was “unnatural” — those mountains are highly mineralized, and water flowing through such rocks will become acidic all on its own.

If this sounds interesting, you might want to read the April, 2001, edition of Rocktalk, the quarterly publication of the Colorado Geological Survey. Almost all of the 16-page newsletter is devoted to Summitville, from the volcanic geology of the region to its mining history and recent reclamation efforts.

It’s the best summary we’ve seen.

It’s available on the Survey’s website at, and it’s also free for the asking from Colorado Geological Survey, 1313 Sherman St. Room 715, Denver CO 80203, telephone: 303-866-2611,