Omco (Mineral County) We Visited: 6-7-2003
Our Dinner: Home-made garlic beans and Hebrew National Beef Knockwurst
38 36' 29"N, 117 53' 32"W - STEWART SPRING quad

Directions: Highway 50E from Fallon 47 miles to Middlegate and the junction of Highway 361; Turn S on SR361 for 36.1 miles, through Gabbs, to a large dirt road; drive S for 15 miles; turn right on local dirt road for 8 miles

From Fallon: 106.1 miles

4WD or high clearance desired

What Was

The Olympic Mines Company built this seventy ton cyanide mill way back in 1917 after gold was discovered in the area two years before. It burned down and was rebuilt as an 80 ton mill in 1919, where it produced refined ore until 1921. Mining continued on a lesser basis on individual claims for another 20 years or so, even after an earthquake caused the mine workings to collapse. (Paher)

The Royal George group of nine claims was located in 1915 by James P. Nelson. The property was sold shortly after to San Francisco interests that organized the Olympic MInes Co. Omco is an abbreaviation of the name of this company.

The Olympic Mines Co. erected a 70-ton cyanide mill in 1917. This mill burned down in 1919 and another of 80 tons capacity was built in 1920, which was closed in 1921. The mine has been operated at various times by lessees, and in 1929 it was sold at a tax sale. On December 20, 1932, the mine workings were caved in by a severe earthquake that occurred in this vicinity. In 1936, the mine and mill were being rehabilitated by .H. Simpson and associates of Simon.

Production, principally by the Olympic Mines Co., has been about $700,000, princeipally in gold.

The Omco mine is developed by a shaft 225 deep, inclined 43 degrees. Total lateral worksings comprise about 3,000 feet.

The Omco mill equipment includes a Hendy crusher, Hendy tube mill, Hendy ball mill, a Door duplex drag classifier, two 12 x 14' Oliver filters, two Door agitation tanks, three Door thickener tanks, pumps, refinery, and other cyaniding quipment. An extract of 93 percent is reported to have been made in milling.

The mine and mill are served with power by a branch transmission line from Simon.

In 1936 a 2 inch diamter pipe 4 miles long was laid to carry water from teh collar of the Simon shaft to Omco by gravity.

-W.O. Vanderberg, DISTRICT REPORT; PROPERTY REPORTS; PRODUCTION; GEOLOGY; ASSAYS; USBM IC 6941 1937

Diagram of Omco Mine from USGS Bulletin #725-H "Ore Deposits of Cedar Mountain, Mineral County, Nevada" by Alfred Knopf

Post Office: Apr 1917 to March 1921

Newspaper: None

What is

Omco is an interesting site for us chiefly because we discovered a couple of things we'd never seen before- empty cans of cyanide, for one- and a giant, fabric-covered wheel, the use of which is a mystery to us at present. Lots of debris including corrugated metal, barrel hoops, and the usual cans and glass.

UPDATE: We have an educated guess as to the purpose of the Mysterious Wheel. Mr. Wayne Kirk from the University of Nevada responded to my query as follows:

The honest answer is that I don't recognize just what the barrel may have been used for, but I would like to offer a couple of ideas to consider. First let's assume that the barrel had closed ends, and that the barrel could be rotated. I notice in one of your photographs that very little iron remains at the mill, so salvaging could account for the fact that the ends are missing. As you may know, at many mills the iron and steel parts were salvaged as scrap for World War II,

I don't think that the barrel was directly involved with the cyanide process because the leaching stage was traditionally done in vats and the precipitation was usually done in zinc boxes.

I am more inclined to think that the device you found was an amalgamation barrel. It takes cyanide a long time to completely react with coarse gold, so the coarse gold was usually removed from the ore by some sort of amalgamation process. Amalgamation barrels were one way of doing this. The barrel was partly filled with ore, a charge of mercury introduced, and water kept the ore in a slurry.

The outer wire and canvas layers you mention are a bit unusual. I suppose that the canvas could have been a way to insure the water tightness of the barrel. The photo doesn't show the wire you mention, but could it have been structural reinforcement?

Please remember that I am not certain what it is, and that I do not represent the Keck Museum, the Mackay School of Mines, or UNR. Gads, that doesn't sound very friendly, but I don't want it to be misunderstood.

So there you have it, folks. For those of you who are interested, I've slapped together a separate page just for this item, with some higher resolution pictures.

UPDATE: We have an answer. The Mystery Cylinder is part of a device called an Oliver Filter. We found one intact at Camp Douglas.


The remains of the mill, with lots of debris
The headframe still standing proudly
A strange fabric-covered wheel
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