May 07

Mining Mercury

Inside the Rinconada mercury mine in December 1965. ©2010The Tribune/Jim Vestal

Some elements get all the breaks, like gold and silver.
Not mercury or chromium. They live in the hard-knock-life neighborhood of the periodic table.
No respect, no accolades. How many books have you seen about the gold rush? Shelf loads. Who’s ever heard about a mercury rush? Yeah, and how many books are there about mercury mining?
Let me think a minute.
California’s gold rush of 1849 and Nevada’s silver rush 10 years later brought a flood of experienced miners and trained thousands of rookies. When work in the Sierra Nevada tailed off they needed to find something to do.
The industrial revolution and subsequent wars created an appetite for raw materials. The Coast Range, had ore that could be refined into mercury and chromium.
In his novel “Angle of Repose”, Wallace Stegner describes workers riding down the elevator of the New Almaden mercury mine and looking up to see stars winking in a mid-day sky. The shaft was so deep that daylight could not wash the starlight out.
Mercury is an odd metal that fascinated the ancients. Liquid at room temperature, it will splash into quickly rolling spheres when spilled on the floor.

Paul Merrick, ex-sheriff turned mine operatator, heads for the upper level entrance to the historic Rinconada quicksilver mine near Pozo. © Jim Vestal/Telegram-Tribune

The heavy metal can also acts as a poison when enough is absorbed by the body.
The term “mad as a hatter” grew from the hat making materials treated with mercury. As the poisonous metal built up in the systems of hat makers, they went insane. Daguerreotype photographers used mercury vapor to develop images and destroy their health. I’ll stick to digital, thank you.
There are 17 historic mine locations documented in San Luis Obispo county at one website, though I am not aware of a current active operation.
According to a Riverside Press-Enterprise story by Janet Zimmerman published Nov 25, 2008:

Fish consumption restrictions because of mercury are in effect in many Northern California bodies of water, including San Francisco Bay, the San Joaquin River, Clear Lake and Lake Nacimiento. The source in many cases is earlier mining activities, officials said.

When the Telegram-Tribune article below was written, the Environmental Protection Agency and other work safety regulations we take for granted today had not been created.

December 18, 1965

Mercury mines in the county — the price is right

By Elliot Curry
Staff Writer
In the quicksilver mines of San Luis Obispo County they play a game called “The Price Is Right.”
The game has been going on at the historic old Rinconada mine southeast of Santa Margarita for more than 80 years.
The game is the same, only the players are new.

David Merrick reflected in a pool of mercury in a storage cauldron at the Rinconada mine.© 2010 The Tribune/Jim Vestal

Today the players at the Rinconada are Paul Merrick, former supervisor and county sheriff, and his partner, Gene Monson of Los Osos. They are leasing the mine from George P. Bell, who’s family has owned the property since sometime in the 1880′s.
In 1963 the average price per flask for mercury (quicksilver) on the New York market was $189. This week the quotation has been around $540 per flask. Earlier this year it had soared to over $700.
The price is right, and all through the mountains of the Santa Lucia range the old mines are stirring with life again — like a mercury thermometer on a hot summer day.
Some, like Harold Biaggini’s Buena Vista in the Adelaida district and the Cambria on Pine Mountian, were already in operation in 1964. Others like the historic Oceanic, are being explored to discover what potential is left after the off-and-on exploitation that extends clear back to the 1860′s.
Merrick thinks that the old Rinconada still has a lot of valuable mercury left in her red-hued tunnels and underground “rooms” blasted out of the cinnabar ore.
So far the Rinconada has been shipping only an “occasional” flask of mercury but a new condenser is now being installed to improve the recovery ratio at the mill and it is hoped with better equipment to get into a regular production schedule.
The Rinconada has been mined until the mountain looks from the inside like a Swiss Cheese. A central gallery has been burrowed out of the mountain, opening to the sky from above and leading to chutes below, down which ore can be dumped to cars waiting at still lower levels.
The mine is fully equipped with electric power, compressed air and water systems. Some new exploratory work is being done at what is called the “lower level” now but Merrick points out that no exploration ever has been made of the base of the mountain which spawned the rich cinnabar ore above.

Paul Merrick pours mercury at the Rinconada mine. ©2010 Jim Vestal/Telegram-Tribune

Merrick plans to remove the remaining “crust” of the mountain on one side, exposing it to an open pit type of mining.
When the cinnabar ore comes from the mine, it is dumped through a “grizzly,” a grid of iron rails, which takes out the larger boulders before the ore drops into the crusher. The crushed ore is stored in a 150-ton bin to await treatment.
The Rinconada mill is equipped with a rotary furnace, fires with propane gas. As the rotary furnace turns on a slightly inclined axis, the ore moves toward the heat at the lower end. The heat turns the mercury to vapor before it is drawn into the pipes of the condenser.
As the mercury cools and liquefies it is collected under water which seals the openings in the lower pipe connections.
The new condenser to be installed at the Rinconada has 4,800 feet of steel tubing.
As the mercury is drawn from the condenser it is put into flasks, actually metal cylinders, which hold 76 pounds of mercury each. The flask[s] from the Rinconada are shipped to Quicksilver Products, Inc., of San Francisco, a company which once operated the Rinconada.
In 1963, ore treated in he United States averaged 12.8 pounds of mercury per ton.
Mines in San Luis Obispo have been known to go much higher, however. The Rinconada has taken out ore at times that ran as high as 40 to 50 pounds to the ton.
Merrick has the assistance of his son, David, in working the mine, while a frequent visitor is Bell. Bell’s two daughters, Mrs. John E. Blake of Pozo and Mrs. Junelyn Whiteford, are co-owners of the mine.
Bell’s grandfather, Ruffino Pedriata, an early day hotel operator in both Cayucos and San Luis Obispo, acquired the Rinconada not long after its discovery. It passed to Mrs. Teresa L. Bell, George Bell’s mother, who became one of the better know mine operators of the county.
Bell lives on a farm near the Rinconada now and expresses great hope that Merrick and Monson can make a success of the lease. Bell has had many offers to buy the mine but it has been in the family so long that he refuses all offers.
The first practical working of cinnabar ore in San Luis Obispo County was in 1862 when a party of Mexicans located the Josephine mine, situated on the summit of the Santa Lucia range, about midway between San Simeon bay and Paso Robles. This is still one of the most productive areas.
California produces over half the mercury mined in the United States and most of it comes from the coastal ranges stretching from Santa Barbara to Lake County.
The soaring price of mercury is due to heavy new demands, U.S. consumption having increased about 40 per cent in 1964. The space program is said to be a new user of mercury.
The Atomic Energy Commission sold some of its mercury earlier this year in a move to stabilize the price, much as the government has done since then with aluminum and copper.

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