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Historical Uses for Mercury in Washington

In the past, mercury was mined in our state. It was used to extract gold, and it was used in a variety of now-obsolete equipment.

Older mercury-containing equipmentbarometer

As many uses of mercury are phased out, we will be left with the legacy of old equipment and even antiques that contain mercury. Some older temperature and pressure-measuring devices, clocks, switches, and other items can contain pounds of mercury, often right in people's homes and businesses.

If older mercury-containing equipment is ever broken or burned, the mercury can be released into the environment. Washington residents may call 1-800-RECYCLE to learn where to take older mercury-containing items.

Mercury Mines

There are two historical deposits of naturally occurring mercury ore in Washington state. The largest source of mined mercury in Washington was in eastern Lewis County near Morton.  The second was in King County, in the Green River District near Cumberland. Both deposits contained cinnabar, mercury sulfide.

The Barnum-McDonnell mine began processing cinnabar after its discovery near Morton in 1913. Miners installed a retort furnace in 1916. A larger retort furnace installed in 1926 brought a period of substantial production until 1929. All production ceased in 1942.

The Roy Mine (also called Morton, Gillespie, or Fisher Mine) opened in 1926 by the Morton Cinnabar Company. This mine was most active in the late twenties. However, it also produced elemental mercury from 1933 - 1938 and during World War II.mine

Inactive and Abandoned Mine Lands--Roy and Barnum-McDonnell Mines, Morton Cinnabar Mining District, Lewis County, Washington is a Department of Natural Resources Division of Geological and Earth Sciences investigation of this old mine site in 2001. The image to the right shows a 10-foot diameter opening 26 feet deep in the center of the Barnum-McDonnell Mine access road. Photo: Department of Natural Resources, 2001.

The Royal Reward and Cardinal Reward mines in in King County produced mercury in the late 1950's.

From 1916 - 1961, mercury mines in Washington produced 503 thousand pounds of mercury. Most of this was used in industry, and some was used to concentrate gold-bearing ores.

Gold Mining

Historically, gold miners used mercury to extract placer gold from streams and seams. More recently, a hardrock gold mine in Ferry County, Washington that emitted 777 pounds of mercury in 2000, closed in 2003.

According a California study by the US Geological Survey, hydraulic mining with water cannons was a cost-effective and popular mining method by the mid-1850's. Gold particles were recovered by mechanical settling in troughs (riffles) within the sluices and by chemical reaction with liquid mercury to form gold-mercury amalgam.

The California study further says that during the late 1800s, under the best operating conditions, sluices lost about 10 percent of the added mercury per year, but under average conditions, the annual loss was about 25 percent. Overall mercury loss is estimated to be 10 to 30 percent per season, resulting in highly contaminated sediments at mine sites, especially in sluices and drainage tunnels. See Mercury Contamination from Historic Gold Mining in California (leaving Ecology).

Mercury was also used to recover gold by amalgamation in non-placer mining, such as in hardrock mines, drift mines, and dredging operations. Modern suction dredging for gold allows mercury to be trapped in the riffles of the sluice box, where it can be readily collected.

Mercury Medicines

Mercury has even been used in medicine. Merbromine, marketed as Mercurachrome, was an antiseptic that was nationally banned in 1998.  Mercury was also used as a treatment for syphilis until antibiotics were invented.