The Geology of Asarco’s Young Mine
The Young Mine is located in Jefferson County, Tennessee, on U.S. Highway 11-E about 15 miles (25 kilometers) northeast ofKnoxville. It is situated near the center of the Mascot - Jefferson City zinc district which lies within the Valley and Ridge Province. Sphalerite deposits occur within the Kingsport and Mascot Formations, located in the upper part of the Lower Ordovician Knox Group.
The mine is located atop a physiographic do mal structure known locally as Hodges dome (Fig. 1 0). Geographically, it lies between two low-angle thrust faults: the Mill Spring. to the north, and the Rocky Valley to the south. This structure is cut by numerous high-angle faults, most of which exhibit minor to moderate vertical and/ or horizontal displacement. One exceptional high-angle reverse fault displaces the north flank of the dome downward approximately 100 feet (30 meters). The dome is considered to be of pre-Cambrian age, while the faulting is post-ore and is thought to have occurred during the Appalachian orogeny (Upper Paleozoic).
The mine was developed from a rectangular 7 -compartment shaft which was sunk on the north flank of the domal structure to a depth of 936.4 feet (285.4 meters). Production was started in 1955. Output has increased, due to increased mechanization and the addition of the Beaver Creek shaft in 1989, to a point where the current production of crude ore is approximately 4787 tons per day, yielding an annual production in excess of 1. 25 million tons. Mining is generally by selective open stoping involving three stages: slabbing, backstoping, and benching.
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Zinc Deposits in East Tennessee
The mining of zinc in Tennessee dates back to 1854 although the presence of zinc minerals had been reported as early as 1844 by Gerard Troost, the first State Geologist. When the Mossy Creek open pit mine, in what is now Jefferson City, Jefferson County, was opened, it became the first mine in what is now known as the Mascot-Jefferson City Zinc District. In these early years, only the oxidized ore was removed, and mining stopped when the sulfide ore zone was reached because a method to treat “hard ore”, as it was called, had not yet been developed.
Mining continued at the Mossy Creek operation until 1858, then ceased through the Civil War years until 1867, at which time the property was taken over by the East Tennessee Zinc Company. This company built a smelter to manufacture zinc oxide, but after only a few months of operation, the company became involved in litigation and mining ceased.
In 1882, the Mossy Creek property was sold to the Eades, Mixter and Heald Zinc Company which operated intermittently until 1894, becoming the first substantial zinc mining company in Tennessee as well as the first to produce significant amounts of sulfide ore. This latter was made possible by the construction of a zinc smelter at Clinton, Tennessee, some 45 rail-miles to the west. The Mossy Creek mine was operated or prospected only sporadically thereafter, and was closed by its final owner, the American Zinc Company, in 1919.
In the meantime, the discovery of lead and zinc ore in the Powell River area of Claiborne and Union Counties, some 30 miles northwest of Jefferson City, caught the attention of the mine operators. In 1883, the New Prospect mine was opened with only the lead recovered. By 1889, Eades, Mixter and Heald had taken over, erected a mill and mined the property intermittently until 1897. The lead was handpicked and shipped to New Jersey while the zinc was barged to the smelter at Clinton. There was little further activity until World War II when the very high grade pillars were robbed.
The only other producing mine in the Powell River district was at Straight Creek. It operated from 1880 to 1894, the latter part of this period by Eades, Mixter and Heald Zinc Company, which also built a mill. Beyond this there was only a short period of exploration and mining from 1906 to 1908 and another effort by Universal Exploration Company in the latter part of World War II.