Heritage District in Sunnyvale in Santa Clara County, California — The American West (Pacific Coastal)
Hendy Stamp Mill
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Hendy's "California" Stamp Mill
Following the 1906 Earthquake, John Hendy moved the iron works from San Francisco to Sunnyvale, lured here by the offer of free land, and was operational in 1907. Hendy Iron Works was the first heavy industry in Sunnyvale and was Santa Clara Valleys largest manufacturing concern at that time.
This Hendy “California” stamp mill represented the finest machine technology available in the early nineteen hundreds. This type of gravity stamp mill was one of the most important factors in the extraction of gold, silver and copper ores, from hard rock mines.
The stamp battery was activated by rotating the pulley wheel, made of a dried California Yellow Pine, which turned the camshaft and cams, made of “Adamantine” chrome steel, at 50 to 55 RPMS. The cams raised the 1,000 lb. stamps to a pre-set height. Then the stamps would fall, pulverizing the gold ore between the stamp heads and the mortar dies. The pulverized ore was sifted by a special screen placed across the front of the mortar so the precious metal could be retrieved. It could take as much as 50 tons of ore-bearing rock to recover as little as 2 ½ ounces of gold.
“The reputation and superiority of Hendy mortars is based on experience, design and quality, to the interested engineer, investor or miner. This results in the best gravity stamp battery units of five stamps and over.”
Source: Henry Iron Works Catalog – July, 1911.
In 1986 the mill was purchased by the Iron Man Museum of Sunnyvale from Fredericks great-grandson, Eric.
The restoration and installation of this mill was completed in April of 1996 through the efforts of the Iron Man Museum, the Sunnyvale Historical Society and Museum Association, Mountain Charlie Chapter 1850 – E Clampus Vitus and many members of the Community.
A gift to the City of Sunnyvale and its citizens
Erected 1996 by Mountain Charlie Chapter 1850 E Clampus Vitus,
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Topics and series. This historical marker is listed in these topic lists: Industry & Commerce • Natural Resources. In addition, it is included in the E Clampus Vitus series list. A significant historical month for this entry is April 1996.
Location. 37° 22.886′ N, 122° 1.619′ W. Marker is in Sunnyvale, California, in Santa Clara County. It is in the Heritage District. It can be reached from North Sunnyvale Avenue near East California Avenue. Marker is located at the northwest corner of the Martin Murphy Historic Park. Parking is available via E. California Street. Touch for map. Marker is at or near this postal address: 219 North Sunnyvale Avenue, Sunnyvale CA 94086, United States of America. Touch for directions.
Regionally, this marker is in California’s San Francisco Bay Area, in Silicon Valley, and on the Coast Ranges. It is also on the American Pacific Coast. Globally, it is in North America, on the Ring of Fire, in the Pacific Rim, in the Western Hemisphere, in the Western World, and in the Anglosphere. Historically, it finds itself in what was once New Spain and also Mexicos Alta California.
Other nearby markers. At least 8 other markers are within 2 miles of this marker, measured as the crow flies: Home of Martin Murphy, Jr. (about 300 feet away, measured in a direct line); De Anza Expedition 1775 - 1776 (about 300 feet away); F.E. Cornells Country Store (approx. 0.3 miles away); Del Monte Building (approx. 0.3 miles away); Hendy Ironworks (approx. 0.4 miles away); Joshua Hendy Iron Works (approx. 0.4 miles away); Murphy Station District (approx. 0.4 miles away); City Hall Bell & City Hall Cornerstone (approx. 1.7 miles away). Touch for a list and map of all markers in Sunnyvale.
Also see . . . Joshua Hendy Iron Works. The history of the company transcribed from History of Santa Clara County, California, page 818. Published by Historic Record Co. – 1918 (Submitted on April 30, 2010.)

Photographed by Syd Whittle, April 25, 2010
5. Plaque Mounted on the Stamp Mill
Manufacturers
Sunnyvale, Cal.
Hendy Stamp Mill Manufactured circa 1918
Refurbished by the Iron Man Museum
February 1996
Eusibio Aribas Jerry Morris Lou Tambini Tom Hashimoto John Plaza Lou Spincich John Tullis
Credits. This page was last revised on February 7, 2023. It was originally submitted on April 30, 2010, by Syd Whittle of Mesa, Arizona. This page has been viewed 3,763 times since then and 62 times this year. Photos: 1, 2, 3, 4, 5, 6, 7, 8. submitted on April 30, 2010, by Syd Whittle of Mesa, Arizona.






