Almaden near New Almaden in Santa Clara County, California — The American West (Pacific Coastal)
The Rossi Retort
Photographed By Barry Swackhamer, March 7, 2018
1. The Rossi Retort Marker
This two-tube inclined retort, known as a "Rossi Retort," was named for Louis Rossi who came to New Almaden in the 1920s and built a reduction plant based on his patented design. This style of retort allowed rapid recovery of valuable mercury from high-grade ore.
In operation, the retort was charged with up to 400 pounds of crushed ore per cylinder, sealed, then heated for 8 to 24 house. The mercury sulfide vapors traveled up through the two condenser pipes, where the vapor cooled back to liquid mercury. The condenser pipes terminated into rubber buckets filled with water. Sulphur gases, a byproduct of the roasting process, were released through the chimney on top of the bucket cabinet.
Ore for the retort sat in the dump-truck bed above the retort. A knife gate mechanism regulated the ore feed and would only permit pieces less than 3 inches in size. Fresh ore was fed into the tubes by way of the triangular apron at the bottom of the truck bed.
The Rossi retort was unique because it used a perfect "angle of repose" to ensure the ore chambers were never completely full, thereby allowing freedom of gas movement and ready collection of the escaping mercury vapor.
Erected by New Almaden Quicksilver County Park Association and Santa Clara County Parks and
this page online
Topics. This historical marker is listed in these topic lists: Industry & Commerce • Natural Resources.
Location. 37° 10.483′ N, 121° 50.659′ W. Marker is near New Almaden, California, in Santa Clara County. It is in Almaden. Marker can be reached from Hicks Road near Mount Umunhum Road. Touch for map. Marker is in this post office area: San Jose CA 95120, United States of America. Touch for directions.
Other nearby markers. At least 8 other markers are within walking distance of this marker. Mine Hill (a few steps from this marker); SpanishTown (approx. 0.2 miles away); The “Main Tunnel” (approx. ¼ mile away); The Yellow Kid (approx. 0.3 miles away); English Camp School (approx. 0.4 miles away); English Camp (approx. 0.4 miles away); Site of English Town (approx. 0.4 miles away); Camp Mt. Madonna (approx. 0.4 miles away).
More about this marker. This marker is located in New Almaden Quicksilver County Park near the junction of Wood Road Trail and Yellow Kid Trail.
Photographed By Naqcpa, October 11, 2014
2. This is the Rossi Retort.
It was originally in use on a nearby hill. It was removed and placed in a pile on the other side of Wood Road from the rotary furnace during the cleanup of Mine Hill in 2000. A crew of volunteers with NAQCPA moved it to this site next to the rotary furnace and reassembled it...
Photographed By Unknown
3. The Rossi Retort blueprint
Credits. This page was last revised on February 7, 2023. It was originally submitted on March 13, 2018, by Barry Swackhamer of Brentwood, California. This page has been viewed 414 times since then and 54 times this year. Photos: 1, 2, 3. submitted on March 13, 2018, by Barry Swackhamer of Brentwood, California.
