Eureka Utah

www.sec.gov/Archives/edgar/data/19913/000095013607006226/file6.htm

Lead / Zinc

Lead / Silver

Copper / Gold




HISTORY

GENERAL

Ore, in the Tintic District, was initially discovered in outcrop in 1869. Within a few years most of the major outcropping ore-bodies were being mined and there were 15 -20 exploitation and exploration shafts. In addition to the initial Sunbeam lode (small fissure type ore body) major ore-bodies (replacement type) were discovered along three main structures known as the Gemini (Eureka) the Mammoth and the Godiva-Sioux ore runs (or zones). In 1905 the fourth and latest of the ore runs, named the Iron Blossom was found by Jesse Knight. Anecdotally, the Mormon, Bishop Knight was led to the zone via a vision. However, Knight was familiar with the district and no doubt recognized the altered appearance of the surrounding rocks even though the ore body did not outcrop. This “blind” discovery by Knight some distance east of the outcropping ore runs, opened up the possibility of further deposits to the east. (See sketch below)








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By the end of the 1871, three mining camps had been established – Eureka, Silver City and Diamond City. The growth along the discovered ore runs was steady and most of the early producers were still in operation 40 years later. The Mammoth, Martha Washington, Eureka Hill and Shavers were amongst the earliest producers. As a result of the high grade ores, shipments were sent long distances to smelters in San Francisco, Reno, Baltimore and as far as Swansea in Wales.

Even though many claims had been staked in the eastern portion of the district (Now East Tintic District) before the turn of the century, the only “sniff” of ore was a small outcrop of lead-silver near to the present Eureka – Lily shaft. This outcrop was in an area of intense alteration of both sediments and volcanics. All future discoveries of major deposits in the East Tintic would be blind ore-bodies, based on surface alteration and found by underground geologic interpretation. (See Figure No.3)

E.J. Roddatz became interested in the district about 1906 and acquired a major holding in what is now the Tintic Standard area. Roddatz reasoned that even though the surface rocks were inhospitable, there was a chance of discovery in the Ophir limestone at depth. His ideas worked out and, despite the complex faulting and folding in the area, and with great perseverance, in 1916, he discovered the Tintic Standard deposit. It took two shafts and thousands of feet of drift and winze to make the discovery. Roddatz was amply rewarded. The Tintic Standard Mine went on to become one of the major lead-silver mines in the world.

The Tintic Standard discovery stimulated activity in the eastern part of the district and since the Tintic Standard No.2 shaft (discovery shaft) was sunk in an area of pyritized volcanics, much of the prospecting concentrated on similar alteration zones. The Eureka Bullion, Iron King, Copper Leaf, Eureka Lily, Zuma and Apex Standard shafts were sunk in similar zones. With the exception of the Eureka Lily, none led to an immediate discovery, this would come later after much effort.

Mining geologists attracted by the discovery of the Tintic Standard began to study the district. Amongst these was Paul Billingsley, who, in the early 1920’s, provided the skills that led to the framework for modern prospecting. He observed that the volcanic cover in the east was pre mineral and altered by various stages of the mineralizing solutions contemporaneously with ore deposition. He also recognized that the dikes and fissures cutting the volcanics continued at depth into the underlying sediments. Based on these ideas a long drive on the 700 level of the Tintic Standard Mine was commissioned. The target was projected from a surface exposure of a strong alteration zone, along with persistent dikes in the volcanics. This exploration work intersected the ore deposit that became the North Lily Mine. Similar strategies led to the discovery of the Eureka Standard mine.

During World War II, the United States recognized that in the event of a long war, new sources of raw material would be essential. The US Geological Survey spent 1942 – 1943 studying the East Tintic District. An exploration program seeking blind ore-bodies, was commenced towards the end of 1943. The work progressed slowly and by 1945, four targets had been defined. One of the targets was the Chief Oxide area. This area was centered on a prominent outcrop of oxidized and pyritized volcanics. No major discovery was made via the 75ft deep Chief Oxide zone shaft. (It is interesting to note that Paul Billingsley, late in the 1920’s, had defined the Chief Oxide zone as a prime target.) A drift was driven from the Apex Standard and exploration holes drilled downwards, This also was unsuccessful. It has been subsequently proven that both Billingsley and USGS were correct in their thinking. The Burgin deposit lies within the Chief Oxide zone and below the Billingsley exploration holes.





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In summary, district production slowly increased through discovery of new mines and peaked between 1921 and 1930, when according to data from the U.S. Bureau of Mines (Morris and Mogensen (1978)) production for the decade from the combination of the Tintic and East Tintic Mining Districts reached 4,250,000 tons. From that peak, production decreased to a low of 662,000 tons between 1961 and 1970. Production from the Burgin Mine led to a second peak of 1,200,000 tons between 1971 and 1976.



The comet struck during Devonian Times.

pubs.usgs.gov/bul/1142k/report.pdf