Centennial Eureka Mine -- 1910
THE CENTENNIAL EUREKA MINE
The Centennial Eureka also known as the Blue Rock Mine is the number one single producer of gold and silver ores in the entire Tintic Mining District, with: 656 thousand ounces of gold (0.42 opt); 23.4 million ounces of silver (15 opt); 80 million pounds of copper (2.56%); and 20 million pounds of lead (0.64%); from 1.56 million tons of ore, subsequent to 1900. These were “recovered metals” and not total metals contained in the mined ores. Antiquated early smelting methods were inefficient. The Centennial Eureka mine dump was re-processed in 1993 and 1994. An additional 0.10 opt. gold was recovered from the mine dumps.
Noranda Mining Company carried out an underground mapping and sampling program in 1988, and determined that over 1 million tons of possible ore remains unmined in the Centennial Eureka Mine with an estimated average grade of 24 opt silver; 0.42 opt gold and 2.5% copper. Noranda did not move ahead toward production because an important portion of the mine property was owned by another company, and could not be acquired at that time. Gemini Mines LLC now owns a full 100% of the Centennial Eureka mine property. A copy of Noranda’s final report is available.
The Centennial Eureka mine has a 2,000 foot deep shaft (partially repaired) plus a 2,600 foot long haulage tunnel (Holden Tunnel) which accesses the 550 level of the Mine. The Holden Tunnel connects the mine shaft to a proposed mill site adjacent to U.S. Highway 6, and 2 miles from a loading facility on the Union Pacific Railroad. The Holden haulage tunnel remains open.
The Centennial Eureka Mine was the “Flagship Mine” for the former USMS&R. Mine-run ore from the Centennial Eureka Mine was smelted at the Midvale Smelter near Salt Lake City, and was transported from the mine to the smelter by railroad.
The Centennial Eureka Mine was referred to locally as the Blue Rock Mine and began operations in 1886. Initial production came from ore that was exposed at the surface in the New Years stope. Later, a shaft was sunk to test for ore at depth. Three major blind ore pipes, the California, Virgina, and North Carolina were developed beginning at approximately the 500 foot level of the mine. Mining stopped at the water table located at approximately 2,000 level of the mine.
USMS&R records indicate that from 1886 to 1897, 48,571 tons of ore was produced averaging 1.22 ounces per ton gold and 67.76 ounces per ton of silver. No copper recovery was reported. Mining during this period focused on the near surface high grades ores. From 1898 to 1913, 1,190,006 tons of ore was produced, averaging 0.44 ounces of gold per ton, 14.26 ounces silver per ton, 9.55% copper and 2.18% lead. The mine continued oporations until 1928, when mining were ended. From 1928 to 1953, lessees produced small lots of ore from the mine.
The Centennial Eureka Mine did not close down for lack of ore, its closure was due to property boundary limitations, antiquated engineering, and unfavorable economic conditions. Many targets that were proposed by early geologists were never developed. No exploration have been directed toward testing the projections of the many mineralizing structures both above and particularly below the water table.
Recently, the Holden Tunnel has been reopened and rehabilitated, which was a haulage tunnel from the main Centennial Eureka shaft. A manway has been installed in the shaft to access the 400, 500, 600, and 700 levels of the mine. This rehabilitation work has allowed for detailed sampling and mapping of the upper levels of the mine.