Tintic, Sioux Mill

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This page was last updated on November 10, 2025.

Sioux (Farrell) Mill

(The focus of this page is the surface workings of the Sioux mill, as visible in photographs, as well as a general description of the mine, with minimal coverage of the geology and financial returns. Also to establish a timeline using sources not previously readily available.)

"The Farrell mill works the ores from this group of mines, while a tunnel to go into the mountain 4,000 feet and already in a distance of over 1,000 feet since last May, is under direction of Mr. Robinson and is supposed to be connected with the mining companies named. The Sioux and Utah are on the east side of the mountain from the Mammoth and Ajax, and the tunnel is on the west side of the range, so that the ores from the mills, once the tunnel is completed, will all come to the west side on which are the mills and the railroads." (A Hand Book on the Mines, Miners, and Minerals of Utah, by Harry W. B. Kantner, published in 1896)

The Sioux mill at Mammoth (or Robinson) was first announced in mid-February 1895, and was to be built on property already owned by the Sioux Consolidated Mining and Milling company. The mill itself was built 200 yards east of the existing Mammoth mill at Robinson. The spur (or "switch") was built east from the New East Tintic line. In later years, the Sioux mill was known as the Farrell mill, named for Franklin Farrell, the largest investor, who lived in Ansonia, Connecticut, and visited Utah to oversee the construction of the mill. Farrell had purchased the rights to the milling process that was to be used. (Salt Lake Herald, February 19, 1895)

The Sioux mill had 20 stamps and a daily capacity of 60 tons, compared to the Mammoth mill, which had 60 stamps and a daily capacity of 180 tons. (Salt Lake Herald, May 9, 1895)

Construction of the Sioux mill began in late June 1895. Frazer & Chalmers had the contract for the mill machinery, and the building to house it, with a completion set for 90 days. Trent & Company had the contract for the boilers and other power equipment. The retaining walls and building frame was completed by late August, but there were delays in the delivery of the machinery. Carloads of machinery began arriving in late September, with the final delivery coming in mid-October. By the first of December, ore was being stockpiled in the ore bins, and the crusher had been running for "over a week" passing crushed ore to its own ore bin. By the third week of December, the Sioux mill was in production and was shipping three carloads of concentrates per week to the smelter. (Salt Lake Tribune, June 29, 1895; Salt Lake Herald, July 14, 1895; August 24, 1895)

(The new Sioux mill reached an agreement with the nearby Mammoth mill to use that mill's water supply, from the Cherry Creek Aqueduct completed in December 1894.)

August-September 1895
By late August 1895, the Sioux mill building was essentially complete, and the company was waiting for the delivery of the mill machinery. By late September, the mill building was being painted and made ready for the installation of the mill machinery, which was not yet delivered. Throughout October, the machinery was delivered in several separate shipments in a large number of car loads. (Salt Lake Herald, August 24, 1895; September 27, 1895; October 11, 1895; October 23, 1895)

January 28, 1896
"L. C. Trent visited Mammoth during the week. He reports the new Sioux mill doing splendid service and handling about eighty tons per day. This plant was designed by L. C. Trent & Co., who also furnished a portion of the machinery." (Inter-Mountain Mining Review, January 28, 1896)

December 26, 1897
"One of the long-felt wants of the district has been a custom mill. Messrs. Peyton and Snyder appreciated this fact and leased the Farrell combination mill at Robinson, which was erected by the Sioux Consolidated Mining company. For several months they have kept its 20 stamps dropping constantly on ores from all parts of the district, and have successfully treated ores from the Bullion-Beck and Mammoth dumps, and from the Humbug, Swansea and North Star mines. The average weekly shipments are one bar of bullion and three carloads of concentrate." (Salt Lake Herald, December 26, 1897)

(By mid 1899, ore from the Mammoth mine was being milled at the Sioux mill, with the Mammoth mill being idle due to needed repairs. After a recent breakdown of its concentrating tables, the Mammoth company had shut down the Mammoth mill, and laid off its master mechanic, who promptly took a similar position with the Sioux mill, which was being run as a custom mill by leasers.)

The Sioux mill shipped its last carload of concentrates in mid January 1900. It sat idle until November 1901 when it was sold by Franklin Farrell to a group headed by Robert Grant, the former general manager of the Sioux mine, with plans to restart it as a custom mill. But the plans never took shape and the mill remained inactive. The sale price was reported as $30,000, for the purchase of the mill in which the machinery alone was worth $80,000.

By May 1903, the Sioux mill was no longer in operation and its machinery was to be sold. In July 1903, the building and machinery were sold to a salvage dealer. By early September, all of the timber framework had been removed. The last of the timbers were moved to Santaquin in mid November.

Sioux Mine

The Sioux mine was on the east side of the Tintic mountains, across the Sioux Peak ridge from the Mammoth mine, which was on the west side. On the Mammoth side of Sioux Peak was the Ajax mine, near to the Mammoth mine.

(Read more about the Sioux Mine)

Sioux-Ajax Tunnel

The Sioux-Ajax Tunnel company was a separate enterprise; completely separate from both the Sioux Mining company, and the Ajax Mining company.

The Sioux-Ajax tunnel was a project of the Tintic Mining & Development company. The tunnel had its starting point between the Mammoth and Ajax properties on the west side of Sioux Peak, and was headed for the Sioux-Utah possessions on the east side of the mountain.

When finished, tunnel was meant to enable the companies to unload their ore by means of an underground tramway, into cars of the New East Tintic railway, on the Mammoth side of the mountain. From there it is a short haul to the Oregon Short Line and Rio Grande Western at Mammoth, so that the ore is handled but once from the mine to the smelter.

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