Launched in 1928, the Park City Consolidated Mine (Park Con) was a significant ore producer through the next decade. In 1936, the mine’s general superintendent, Gloyd M. Wiles, wrote a detailed report for the U.S. Bureau of Mines on mining methods and costs in the mine. This technical document provides a look into the complexities of hard-rock mining in the Park City area.
From its inception to November 1935, the mine produced 4,525 ounces of gold and 2.4 million ounces of silver from 155,135 tons of ore. This works out to about 12.5 ounces of silver to the ton.
The mine, located near today’s St. Regis Deer Valley hotel, was served by the Denver & Rio Grande Western and Union Pacific railroads. The railroads shared trackage rights on the spur connecting the mine to Salt Lake City, and ultimately transported ore to a concentrating plant in Midvale.
Most of the ore mined at the Park Con was confined to lode deposits in three main fissures of Weber quartzite – called the Silver, Roosevelt, and East Crescent, respectively. A vertical shaft was sunk to the 400-foot level, and then two winzes (inclined shafts) drove to the 1,000-foot levels of the Silver and East Crescent fissures. Drifts (side tunnels) were worked at multiple levels along the winzes. At the time of the report, a crosscut was being driven at the 900-foot level to improve ore transfer, water mitigation, and ventilation.
Exploration (a.k.a. “development”) was carried on by crosscutting, drifting, and raising. Diamond drilling of core samples into the shattered veins and native quartzite “country” rock wasn’t worth the effort, Wiles noted.
One difficulty underground had to do with the swelling and sloughing faced when mining operations encountered porphyry and limestone adjacent to the fissures. “Swelling then takes place within a few hours after they are opened to the atmosphere,” Wiles wrote. “…Walls and ore matrices such as these demand individual attention in the various parts of the mine and present individual problems of wall support if safe, clean mining is to be accomplished.”
In other words, the geology posed a danger of collapse. This called for a lot of cut-and-fill and open-stope mining with timber support. The report describes sophisticated 8 x 8-inch Douglas Fir “post, bridge, and cap” timber structures and other carpentry necessary to shore up the workspaces.
Credit: Park City Historical Society & Museum, Park Con Mining Company Collection
When it came to mining, pneumatic drilling and blasting were the order of the day. In the rock typically encountered, a miner and two muckers could advance a 6 x 8-foot heading as much as five to six feet in eight hours. “Usually 12 holes and 60 to 80 sticks of 30-percent-strength powder suffice to break the round,” Wiles wrote.
Ventilation also proved a challenge. “The country rock contains an inert gas, probably nitrogen and carbon dioxide, which ebbs and flows from the workings in accordance with the barometric pressure. When the barometer is falling this gas enters the mine workings and so replaces the air to such an extent that even a carbide lamp will not burn. Conversely, when the barometer is rising, the air flows into the rock from the workings, and the most remote heading will contain pure fresh air.”
[Mines can breathe? Indeed! Anybody who has stood in the cool breeze emanating from the Spiro Tunnel on a hot July day knows that is true!]
The company had a 30-horsepower centrifugal fan to draw air from the surface and deliver it to the working faces through galvanized iron tubes. “Four hours are allowed between shifts so that the mine air will be as pure as possible when workmen go on shift,” Wiles noted.
The mine also had four pumps capable of lifting 1,100 gallons of water per minute, and an electrical system to power the various equipment needed.
Not surprisingly, the workforce reflected a range of talents. Beside a cadre of miners and muckers, job functions included an electrical/mechanical engineer, two electricians (and two helpers), three mechanics, three pumpmen, two timber framers, a blacksmith, and a steel sharpener. In administration, roles included geologist, assayer, cost-and-time clerk, and stenographer, among others.
Wages reflected the labor spectrum. For an eight-hour day, shift bosses earned $6.75. Master mechanics made $6.50; hoistmen $5.50; and electricians $5.25. The shaft timbermen and shaft miners made $5.75. Regular miners made $5.25 and muckers $4.75.
Rounding out the report is a dollars-and-cents analysis. It cost about $3.41 to produce and hoist one ton of ore. Development accounted for 29% of the cost, mining 36%, transportation 22%, general 2%, pumping 6%, and surface operations 5%. Across all those categories, labor accounted for 71% of the costs. Quite a way to make a buck!
Some of this information was discussed during a members-only hike for the Museum this summer, lead by Michael O’Malley and Utah Open Lands’ Wendy Fisher. To find out about the hikes, and join them as one of your benefits, become a member with the Museum. The author expresses appreciation to David Nicholas for assistance in preparing this article.