Empire Mine State Historical Park
The Empire Gold Mine was the largest, most profitable gold mine in California’s history. It was located in the area that became the town of Grass Valley , about 50 miles northeast of Sacramento. Today that mine, out of service since the 1950’s, sits at the heart of a California State Historic Park. Going down to work in the mine In 1850, gold bearing quartz was discovered in the mountains of California. Gold in this form is much harder to mine. Since it is not pure, you can’t pan it out of the water. Instead “hard rock” methods must be employed. The rocks have to be drilled or blasted from the ground, and then crushed to a powder. The powder was then mixed with copper covered with mercury. The gold and mercury mixed together formed an amalgam that was separated from the copper. Then the gold was purified. In 1905, the mine adopted a method that used cyanide instead of mercury. These methods both created issues of water and ground pollution. The cleanup of the area went well into...