Colorado open-pit mining

Twenty years ago, the old mine head-frames, piles of ore and relics were the only evidence that mining ever existed in Cripple Creek. But when technology and the rising price of gold made open pit mining economically feasible in 1994, the landscape was changed forever. My dad and I took an escorted company tour of the Cripple Creek and Victor Gold Mining operation, and we bounced around in a van to the very bottom of the mind-boggling pit.
Here's Open Pit Mining for Dummies:

1. An international company secures exclusive mining rights to some 6,000 acres of Colorado high country behind Pikes Peak. They put up a fence and lots of no-trespassing signs.

2. They scrape off the ancient forests, the paper thin top soil and "overburden" rock. With massive equipment, this takes only a few minutes per acre. They start making a new mountain with all the worthless stuff.

3. They pulverize the bedrock with carefully mapped underground explosions, and pile the rubble on Euclid trucks. This is done in 12 hour shifts, 24/7.

4. The ore is hauled to a crusher, where it is ground into pieces no bigger than 3/4 inch.

5. A gigantic mountain is made with the crushed ore, and the top is drenched with sodium cyanide.

6. After 6 months, the cyanide finally leaches to the bottom of the mountain.

7. The "mud" that runs out is captured. It contains gold and silver.

8. This poisonous liquid is processed at high heat, and the $700,000 gold bars are sent out of the country. (40,000 tons of Colorado mountain might yield 1/2 oz. of gold.)

The Pit

Smiling in the maw of the monster shovel

The crushing operation

A 80,000 pound load arrives at the crusher

The cyanide leach pad viewed from Cripple Creek. The black lines on the top left are the cyanide hoses.

All that glitters...

This method of mining is used in places where minerals are near the surface. The pits typically just keep getting bigger until the minerals are exhausted, or the increasing ratio of overburden to ore makes it uneconomic. When this occurs, the best use of old pits is for solid waste landfills, provided the pit doesn't fill first with toxic water.

Of course the mine company has a well-publicized "reclamation" process, but it can take thousands of years for waste dumps to become acid neutral and stop leaching into the environment. At 9,000 feet, forests take centuries to regenerate. Mining does bring a few good jobs to the area, but the profits leave the country. There are no long term studies on harm to the environment with cyanide leaching. It hasn't been done long enough. I'm looking down at my gold wedding ring right now-- we're all guilty.

And here's a final thought: All the gold produced worldwide in a year could fit in the average person's living room.