Located in the southern Oquirrh Mountains, Mercur became internationally famous as a gold mining town around the turn of the twentieth century, at which time significant technological innovations were made by miners who sought to make the unusual ore profitable.
The West Valley mining district, the first in Utah, organized in 1863, included the entire Oquirrh range. The western sides of these mountains later were made part of the Rush Valley district. In 1870 the western section was further divided into the Tooele, Rush Valley (or Stockton), and Ophir (or East Canyon) districts.
The ore bodies in Ophir Canyon eventually were developed and mined. In the spring of 1870, prospectors moved past Lion Hill, the southern boundary of the mining district, into what was later called Lewiston Canyon. There they found outcrops of silver ore, and soon much of the area was being prospected and mined. The town of Lewiston was built as part of this activity, and the area became known as the Camp Floyd mining district.
At that time there were two known veins of ore at Lewiston. One was the gold vein containing large amounts of cinnabar, or sulphide of mercury; the other was a vein of stibnite rich in silver. Captain Ebenezer H. Shaw bought and developed what he called the Sparrowhawk Mine to explore the silver vein. Other claims of significance at the Lewiston camp in 1871 included the Silver Cloud, Mormon Chief, and Grecian mines.
Shaw built a mill in the canyon, and attempts were made to develop the ore bodies. A few silver bars were produced from the veins, but attempts to amalgamate the gold ore failed. The mill was modified, but the gold still could not be separated from the ore. Assays showed that gold was present, but there were no known techniques that could separate the millions of dollars of microscopic gold from the claylike ore. This was a unique situation for western miners, who had made most of their rich discoveries from placers. Amalgamating mills could not stamp the ore fine enough, nor could smelting furnaces reduce the ore so that the gold could be removed.
Captain Shaw abandoned the canyon, leaving behind his mill, offices, buildings, and the town, which soon became cattle pasturage. By 1873 the camp had produced its maximum in silver--11,000 ounces--but the ores were too low-grade and difficult to sort. After 1874 the ore produced was insignificant. From 1871 to 1881 this district produced 46,000 ounces of silver but no gold, lead, or copper.
After the abandonment of Lewiston, a prospector occasionally came through the canyon. One such prospector was a man of German descent named Arie Pinedo. He obtained the property from the government and also had a patent. But he was not interested in the area's gold or silver; he wanted to mine mercury, and it was from the German word for mercury, merkur, that the new strike was named Mercur.
It was at this time, 1891, that John Dern and E.H. Airis, prosperous farmers from Nebraska, secured options on the mining property from Pinedo. Visiting the United States at that time was William Orr, an Australian promoter of the McArthur-Forrest cyanide process, a new method for reducing low-grade ores, such as those found at Mercur. This process proved to be what was needed for Mercur mining. The Mercur Gold Mining and Milling Company had been organized in 1890 to treat the ore by pan amalgamation. A new mill was built at Manning, down the southern slope of the mountain.
As more experience was gained in processing the Mercur vein ores, the Manning mill was expanded, first to 50 tons daily, then in 1893 to 100 tons, to 200 tons in 1896, and soon after to 500 tons. In January 1895 the Salt Lake and Mercur Railroad completed a road from Fairfield up a twisting route through Manning Canyon to Mercur. Captain Joseph DeLaMar bought the Golden Gate group of mines next to the Mercur mine in 1895, and by 1897 the increased capacity of the Manning mill allowed the Mercur company to work on low-grade ores.
During 1897-98, the Golden Gate Mill was built with an original daily capacity of 500 tons, one of the largest production mills in the United States. The longest single electrical transmission line in the country carried power to the mill from a plant in Provo Canyon.
In 1899 DeLaMar's Mercur Mines Company and Dern's Mercur Gold Mining and Milling Company merged to form the Consolidated Mercur Mines Company. At this time all the ore from the combined mines was treated at the Golden Gate Mill; and, after its opening, the mill at Manning ceased treating Mercur ores and was used mostly for processing tailings.
In its first three years the company treated over a million tons of ore, extracted four million dollars in gold, and paid dividends of more than one million dollars, with the mill processing nearly 900 tons a day. However, tailing losses were high at $1.30 per ton, an expense that had to be reduced. For the next ten years, until the demise of Con Mercur, time was spent trying to solve extraction and profit problems.
The year 1902 was disastrous to the town of Mercur. A fire roared through the business district, destroying everything in its path. The town never quite recovered, because mining profits were diminishing. For the next few years tailing losses were heavy, but the use of lime instead of caustic soda proved to be cheaper in the cyanide process. The year 1907 was less profitable than expected because of the lack of storage capacity at the mill, mine trouble, a shortage of coal, power trouble, and repairs needed in the shafts. A new slime mill was built with some success, however.
More experiments in 1908, such as using zinc shavings instead of dust, did not prove efficient, but the slime plant was succeeding in reducing tailing losses. Finally, in 1913, the mines were shut down, operations at the Golden Gate Mill ceased, and the once thriving town of Mercur was abandoned.
Today, Mercur ore is once again being processed. Barrick Mineral Company is operating a newly built cyanide processing plant. Although great quantities of gold ore are being processed, there is no town in Mercur Canyon. Unlike the miners of the turn of the century, mine employees now commute to the mine and mill.