Stamp Mill

Foster’s Prospector Park is not your typical playground and is aimed more at history enthusiast who want to learn a little about the gold mining past of Sonora and the surrounding area. There are no picnic tables or benches for relaxing but there are three pieces of old mining equipment, each with a plaque explaining how each piece of equipment was used in gold production as well as the history and where it came from.


The first is the five-stamp mill which was used to crush rock and extract gold from the ore. This particular stamp mill was built around 1900 and was used to crush rock here in Tuolumne County. It was donated to the city of Sonora by Pete Tomasevich of Stent, CA.

The second piece of equipment is the arrastra, which comes from the Spanish word “arrastre” meaning to drag or pull. The purpose of this crude device was also to crush gold-bearing rock to free the precious metal, and it worked well provided the operator employed a hearty ox or mule to turn the spindle. The drag stones and two of the liner stones were used at Carson Creek during the gold rush. They are currently owned by the Bureau of Reclamation and are on loan to the City of Sonora for the purpose of this display.

The third and final piece of equipment is the impulse wheel, which is simply a water wheel used to convert the flow of water into electricity or mechanical energy. Impulse wheels were used to power stamp mills as well as remove unwanted ore and water from deep within the mine shafts. This particular impulse wheel was used at the O’Hara Mine at Brown’s Flat one mile north of Sonora. It was gifted to the City of Sonora by a resident of Copperopolis named Charles Stone.

Prospector Park is located on Bradford St. just off W. Stockton St.

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