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Mercury mining in Napa County

Mercury mining in Napa County


While the California gold strike played a significant role in Napa County history, it was the discovery and mining of local cinnabar deposits that exerted a greater local influence. Beginning in the mid-1800s, this unassuming reddish-brown ore and its refinement into quicksilver, aka. mercury, generated a thriving and prosperous Napa County industry for decades.

In the 1860s, two pairs of local prospectors, A.J. Bailey and J. Cyrus, discovered significant cinnabar ore deposits in the eastern hills near Calistoga. The Phoenix Mining Company, the first cinnabar mining company in Napa County, was established on that site in 1861.

A second prospecting duo, Seth Dunham and L.D. Jones, discovered cinnabar about 14 miles north of Berryessa in the northeastern corner of the county. The resulting mining company was originally known as Excelsior, then Redington and finally Knoxville.

Over the next decade, many other cinnabar deposits were found throughout Napa County. With  names like Red Elephant, Great Western, Ida Easley, Aetna, Ivanhoe and Mammoth, they were located primarily in the north, northeast and northwest hillside regions of Napa County  

A second sizable cinnabar deposit was found in the western hills between Oakville and Rutherford. The La Joya Mine, later the Summit Quicksilver Mining Company, was established in 1865 west of Oakville. Two more mines in this vicinity were the Oakville and Bella Union. In 1868, they merged to become the Bella Oak Mine, the namesake of the Oakville-Rutherford lane.

With all these nearby mines, Rutherford became a cinnabar boomtown. It was once a bustling community in the days when the raw ore and refined mercury were loaded onto the trains at the Rutherford depot, and workers needed housing and goods.

To produce quicksilver, or mercury, the extracted cinnabar was first coarsely crushed and then loaded into retorts, large metal kettles that were heated to convert the cinnabar into mercury.

At first, the kettles were open, which allowed the poisonous fumes to escape freely. Soon, the vegetation nearby died and the soil became barren. Eventually, condensers were placed over the retorts to capture the gases, but the odor of the refining process could still be detected for miles. The finished product was poured into large, nonbreakable flasks for transportation to markets throughout the nation.

The cinnabar operations were financed by the sales of stock, and many fortunes and community improvements were made due to the stock dividends. The list of the shareholders are those now considered to be the “movers and shakers” from Napa County’s past.

Those dividends were generated in part by the great industrial demand for quicksilver. It was a key element in the amalgamation process used to recover gold and silver from their raw ore. It was also used in the manufacturing of fulminating caps for explosives, as well as in the production of drugs and paints. In later years, it was used in weaponry production, heat gauges, dental fillings and early radio electronics.

Between 1864 and 1903, Napa County was one of California’s leading quicksilver producers. By the end of World War I, a total of $15.2 million worth of quicksilver had been produced in Napa County. The Knoxville mine, the third largest mercury producer in California, survived longer than all the other local cinnabar operations. During  World War I and II, the Knoxville profitably produced large quantities of mercury for weapons.

While cinnabar, its mining and processing has been proven to be toxic, at one time it mades its own contribution to the growth of Napa County.

Rebecca Yerger is a Napa historian who contributes a monthly column to the Register.

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