During the California Gold Rush, Napa’s Oat Hill Mine was one of the leading producer’s of the ore, cinnabar. When processed, cinnabar produces quicksilver, more commonly known as mercury.
Quicksilver was a popular material for gold miners, and as the Gold Rush boomed, so did the demand for mercury. Quicksilver was unintentionally discovered in Napa County in 1860 by a group of businessmen from Napa who were out inspecting the hills in hopes of finding silver, but they ended up finding large quantities of cinnabar.
The Oat Hill Mine, also known as Napa Consolidated Mine, produced the largest amount of quicksilver in Napa County. The mine was constructed in 1876 and operated sporadically until the mid-1980s, when it was disabled for safety reasons. The mine was located above the Palisades Mountains to the east of Calistoga and about three miles north of the Aetna Springs Resort. As more people ventured to the Oat Hill Mine, a modest town sprouted. The population of the mine town was approximately 350 people and included a church, a Wells Fargo Express office, post office and store. During the height of its production, the mine employed 150 Chinese laborers and about 115 white men.
It took almost 20 years and three attempts to construct the Oat Hill Mine Road. The road was used to accommodate travelers between Calistoga to the mines, and it also allowed some travelers to bypass the Lawley Toll Road. 1873 marked the first attempt to build the road. If successful, this road would have connected Calistoga to the town of Knoxville, another prominent mining town. Construction stopped for unknown reasons. In 1876, a second attempt was made to build the road, but again it was halted for unknown reasons. Finally, from 1892-1893, the road from Calistoga to Pope Valley was completed, one fork leading to Aetna Springs Resort, another to the Oat Hill Mine.
This road is now the popular Oat Hill Mine hiking trail. This trail is part of Robert Louis Stevenson Park and intersects with the Palisades Trail. The intersection of these trails holds the historic foundations of a homestead referred to as Holm’s Place. This homestead was built in the late 1890s by Finnish settler Karl Gustov Holm. The wagons carrying heavy loads of quicksilver to the railroad in Calistoga had wooden wheels capped with steel treads to protect them from destruction. These wheels carved deep wheel ruts into the stone of the Oat Hill Mine Road and can still be seen today.
The Oat Hill Mine Trail has two trailheads. One is located at the east end of Calistoga where Highway 29 and the Silverado Trail intersect. This portion of the trail, referred to as the Lower Oat Hill Mine Trail, hikes into the Holms Place intersection. It is about 4.5 miles in length and the elevation climbs from 400 feet in Calistoga to about 4,200 feet. The Upper Oat Hill Mine Trailhead is located on Aetna Springs Road in Pope Valley and leads 3.5 miles to Holms Place. The elevation change is not drastic.
Evans-White is research and volunteer coordinator for the Napa County Historical Society. Research for this article was conducted at the Napa County Historical Society, in the historic Goodman Library Building. The society is open Tuesday-Saturday from 12-4 p.m. and the Society’s Research Library is open Tuesday-Thursday, 12-4 p.m. The society houses an extensive research library, changing exhibition space and presents a variety of programs and events. The Society is a non-profit 501 (c) 3 organization. For more information or become a member visit www.napahistory.org or call 224-1739.
Editor’s Note: This is the first in a series of monthly articles highlighting the county’s past, researched and written by staff, volunteers and members of the Napa County Historical Society.