The Copper Basin
"MINERALS AND MINING OF THE COPPER BASIN"
The Copper Basin is found near the junctions of Tennessee, North Carolina, and Georgia. It covers about 60,000 acres, most of which lie in Polk County, Tennessee. A small area extends into Fannin County, Georgia.
GEOLOGY OF THE COPPER BASIN
The original deposition of rock in the Copper Basin occurred during the Cambrian Period when the sea advanced from the north. There have been many periods of deformation since that time. During the Ordovician Period, igneous rocks were intruding and the first of the ores were deposited. It was also during this time that nearby limestones were altered to marble. Sometime after the end of the Carboniferous Periods, the economically important ore deposits were formed.
The metamorphic rock of the Basin is of the Great Smoky Formation. Of this, about two thirds is metagraywacke (graywacke is a sandstone composed of irregular grains). Of the remaining rock, there is meta-arkose (arkose is a sandstone containing feldspar), metaconglomerates, schists, and slates.
Many of the schists contain staurolite. One exposure contains staurolite blades up to ten inches long. Much of the staurolite has altered to sericite, talc, or chlorite. On Little Frog Mountain, a graphitic schist occurs. Though no fossils have been found in the Basin, the graphite (carbon) gives evidence that life had once existed in the ancient sea which once occupied the area.
The graywacke may contain zeolites, calcite, or garnet. The garnets are crude masses up to one-half fist size.
Limestone or marble occur at depth, but are not found anywhere on the surface. The ore bodies seem to have replaced much of the original limestone through hydrothermal alteration. For the most part, the ore bodies run in parallel belts which are tabular or lens-shaped and curved. The belts tend to be unconnected and run to a depth of over 6,000 feet.
Scattered throughout the Basin are cylindrical or dike like bodies and nodules of pseudodiorite. These grade into the surrounding bodies of metagraywacke. When fresh, this material is often white or gray. It contains a matrix of quartz and feldspar. Running through the matrix may be found black to dark green crystals of hornblende and rounded pink garnets. Pseudodiorite makes an attractive cutting material for gemstones.
The igneous rock of the area is represented by gabbro, a dense, dark rock. This occurs in dikes which may be 100 feet wide and up to four miles long. In some places, narrow pegmatites cut through the metagraywacke. Some of the pegmatites contain rutile and hematite crystals.
The formations of the Basin tend to dip to the southeast. Folding is evident and many anticlines have been identified.
There are three types or ore deposits. Outcrops containing limonite with kaolin and quartz go down to about 100 feet. This ore is gossan. When seen on the surface, gossan appears black from iron hydroxides. The next ore occurs in the lower portion of the gossan. This is a three to four foot layer of chalcocite. Below the chalcocite lies the primary ores which are of economic importance.
MINING HISTORY OF THE COPPER BASIN
The Cherokee knew of the rich deposits beneath the Basin and had actually smelted copper from this area. In 1838, the Cherokee were relocated west of the Mississippi to open the area for settlement by the white man.
The official year of the discovery of copper in the area was 1843. This spurred a copper rush to the Basin. Most of the miners were American, although many arrived from Cornwall, England in the earlier days. Later, Poles and Slavs arrived. In 1847, casks of ore were transported by mule to the closest railroad located in Dalton, Georgia. 1850 saw the opening of the first mine. This was the Hiawassee Mine located at Hiawassee (later Ducktown, Tennessee). During 1853, a wagon road was cut through the Ocoee River Gorge. Ore was transported to Cleveland, Tennessee which was 30 miles closer than Dalton. At this time, Hiawassee resembled a western town. The miners worked hard and would carouse and fight for fun.
In 1860, J. E. Raht (the Cecil Rhodes of the Copper Basin) began to consolidate much of the mining in the area. Mining was the chief industry for miles around. 1861 saw the completion of the first copper-rolling mill. Federal troops occupied Cleveland in 1863. The mill was burned and mining ceased until 1865.
During the early mining days, mules pulled ore cars underground. Some mules, upon entering the mines, never again saw the light of day and hence became blind. Both mules and oxen powered a whim (the wheel where rope was wound) which turned and brought the ore to the surface. Later, steam replaced the animals and by the mid 30's, electricity was used. Battery powered locomotives replaced the mules for underground transport. Originally, work was done by pick and shovel. Later, blasting powder was used which allowed work to proceed at a faster pace, but was very dangerous. In 1872, both diamond drills and dynamite were first used. The dynamite was safer than the blasting powder, but blasts still were not "controlled".
Between the end of the Civil War and the turn of the century, about 24 million tons of ore had been produced. In 1890, a rail line was completed between Marietta, Georgia and Knoxville, Tennessee. It bypassed Hiawassee. A station was opened at McCays (later Copperhill), Tennessee. An interesting feature along the railroad was called "the Loop". It circled the mountain, enabling the trains to travel the change in grade more easily.
The Tennessee Copper Company was formed in 1899. During the same year, the Burra Mine opened in Ducktown. Construction of a smelter was begun in Copperhill. In the early 20th century, the Tennessee Copper Company merged to form a British corporation, The Tennessee Copper Company and Ducktown Sulfur, Copper, and Iron Company, LTD. By 1907, the Tennessee Copper Company was trapping sulfur dioxide gas, which had previously been polluting and denuding the surrounding area. It was condensed to produce sulfuric acid. Copperhill (population 600) was born when the name of the Post Office at McCays was changed in 1908. Copperhill was burned nearly to the ground on two nights in December of 1910.
After the turn of the century, products from the Basin became more diversified. For a short while near the beginning of World War I, TNT was produced and sold to the Russian government. 1922 saw the opening of a flotation plant at nearby London, Tennessee. This plant concentrated copper for the production of copper sulfate. Iron concentrate was produced in 1925. In 1927, London Mill produced the first zinc concentrate.
By 1936, the Tennessee Copper Company was the only company operating in the Basin. The company provided housing for the miners. When promoted, a miner would move to another house higher up on the hill. Then someone would move into his old house. The company store provided food, clothing, and hardware items. Purchases were deducted from paychecks. Unfortunately, many miners never got out of debt.
In 1942, a large sulfuric acid plant was built at Copperhill and liquid sulfur dioxide was produced in 1949. 1959 saw the closing of the Burra Mine. It had operated for over 80 years and had produced 15,636,000 tons of ore! In 1960, the Central Mine began operation. This was a central point between the Boyd, Cherokee, and Calloway Mines. Drifts (tunnels) were cut to the other mines. The ore was transported to this point, the Central Mine, and brought to the surface.
The Tennessee Copper Company was bought by Citiservices in 1963. Tennessee Copper Company became the Tennessee Chemical Company in 1982. To the dismay of the people throughout the region, in 1985, plans were announced that the mines would be closed. On July 31, 1987, mining ceased in the Copper Basin.
Today, you can see the Copper Basin and visit the Ducktown Basin Museum in Ducktown, Tennessee. The information provided there as well as the outdoor views are both educational and interesting.
The Copper Basin is easily accessed from Atlanta by taking Interstate I-575 to Georgia highway 5 to Copperhill. Other ways to get there are by following U.S. 64 East from Cleveland, Tennessee or West from Murphy, North Carolina.
While in the area, be sure to see the Ocoee River Gorge. It is beautiful and has, for many years, been a popular site for whitewater rafting.
MINERALS FOUND IN THE COPPER BASIN
There have been four stages in producing materials in the Copper Basin: (1) Locating the ore bodies; (2) Developing-getting to the ore bodies; (3) Stoping-drilling, blasting, loading, and hauling of the ore; (4) Processing of the ore.
During early mining days, skilled labor was supplied by men who migrated to the Basin from mines in Corwall, England. The ore veins were located on the surface. Often this would be accomplished by looking for gossan. Ground waters of this area, seeping upward, carried iron hydroxides. This infiltrated the surface rocks (in this case schist) causing a darkening of the rocks. This is an indication of possible ore bodies below. These darkened rocks are gossan. After the vein was located, a shaft was sunk and horizontal tunnels (drifts) were dug. The levels were about 100 to 200 feet apart. Drill holes were bored in a pattern covering about 8 x 8 or 9 x 9 feet. Blasting powder was used and the charges were set. The ore would be removed and the drifts extended by the same process. During the early days, one man held a steel rod while another man hit it with a sledge hammer. Later, a water air drill, using compressed air, was put into use. The development of diamond drifts and dynamite greatly improved the efficiency and production. Dynamite was safer than blasting powder though it took many more years to develop a controlled blast.
The ore was blasted and transported to the surface. The copper-haulers then made the trip to the smelters in Cleveland, Tennessee. Originally, teams of four mules, each carrying 500 pounds, made the trip in two days. Later, wagons pulled by mules or oxen were used. One night was spent camping at a halfway house. Upon arrival, the haulers would camp in an area known as Frogtown. Frogtown, Tennessee was bordered by marshes occupied by hundreds of frogs and "contained the shabby establishments of a bevy of morally-loose characters of both sexes who lived off of the campers". When leaving Cleveland, the haulers would transport goods back to Hiawassee.
Later, stopes were used in mining. A stope was drilled upward from a drift and broadened into a V-shaped pattern. The material was blasted and would fall down into the drift for hauling. During the 1940's, compressed air-loading shovels were used to fill a series of connected ore cars. More ore could be brought out at one time using this method. At the time of the mine closings, dynamite had been replaced by another explosive. Blasting techniques had been improved to a science for a "safe" and controlled blast.
In 1985, 59 tons of explosives were set into place with 750 blasting caps. These were all connected by fuses and timed to go off in a sequence. Upon detonation, the entire blast took only 1.5 seconds! The blast broke up 300,000 tons of ore which provided material for eight months!
The original method of processing the ore was to pile it up with wood. The wood was then set on fire and the ore smelted. Processing at the time of the mine closings differed considerably.
The ore was blasted and dumped down a shaft for primary crushing. At the Cherokee Mine, the primary crusher was below sea level. The crushed material was loaded into cars or huge dump trucks and taken to be hoisted to the surface. The trucks were brought down into the mines in pieces and assembled in rooms larger than a high school gymnasium. Upon arrival at the surface, the ore went to secondary crushers where it was crushed to 1/2 inch size. It then went to a ballmill and was ground to a powder. The crushed ore went to the flotation plant where chemicals and oils were added. The slurry was agitated and the valuable minerals floated to the surface. The waste, known as gangue, went to the tailings (dumps).
The material from the flotation plant was separated into three concentrates: iron, zinc, and copper sulfides. The water was removed and they were filtered. The copper concentrate went to the smelters where some of the sulfur content was removed and recovered for sulfuric acid. The remaining copper, called calcine, was roasted in a furnace. The molten calcine, called matte, was poured into ladles to go to the converter. The matte contained about 45% copper.
The copper converter was a brick-lined cylinder into which air was blown through the matte. The sulfur was oxidized into sulfur dioxide which was collected for sulfuric acid. The iron formed iron oxide. Molten impurities were combined with silica to form slag. Being lighter than copper, the slag floated up to the surface and was skimmed off. The slag then went back to the furnace where any residual copper could be recovered. The final slag was then granulated and sold for filler in cement.
Molten copper from the converter was poured into molds (pigs) where it cooled into ingots of blister copper. It was either sent off to be purified by electrolysis or poured molten into water to form shot copper. The shot was used to produce copper salts.
The iron concentrate was roasted. The sulfur dioxide was captured for the acid plant. The sulfur dioxide gas carried off large amounts of iron oxide dust. By slowing the flow of gas, the dust was dropped. The iron oxide was treated with sulfuric acid to produce Ferri-Floc. This is the iron sulfate used in treating water and sewage.
The roasted calcine concentrate was transported by water to settling tanks. The settled solids were sent to the sintering plant. The residual sulfur was burned and the remaining material was fused into lumps. The resulting product, known as sinter, was a very high grade iron oxide used in steel production and pig iron. Again, the sulfur gas was cleaned and cooled for use in the acid plant.
From the original ores, the following products were produced:
- Granulated slag-- for cement
- Blister copper-- for further copper purification
- Copper salts-- for chemicals
- Ferri-Floc-- for water and sewage treatment
- Sinter-- for steel and pig iron
- Zinc concentrate-- for zinc
THE ENVIRONMENTAL IMPACT OF PAST MINING IN THE COPPER BASIN
The mining of the Copper Basin ores was a magnet for people to come into the area during the early days. The work was usually steady and supported generations of people. At the same time, the effects of mining and processing were proving to be disastrous not only to the Basin, but to many surrounding areas.
In 1861, it was noticed that the trees were becoming scarce in the Basin. Wood was needed to fuel the smelters. The ores contained a significant sulfur content. When roasted, the sulfur was released, forming sulfur dioxide which later 'rained" down as sulfuric acid. After the trees had been cut, the gases from the open smelting destroyed the remaining vegetation. In 1876, there was no wood left in the immediate area. Logs were floated down the Ocoee River from Fannin County, Georgia to fuel the smelters. By 1878, about 50 square miles had been stripped of vegetation. Without trees and undergrowth, the top soil began to erode and huge gullies formed. Very few plants or animals survived.
Starting about 1885, the State of Georgia began filing lawsuits because of the damage to timber and crops. In 1904, smoke stacks 150 feet tall were erected to solve the problem and a year later 325 foot stacks were erected. The stacks helped locally but dispersed the gases over an even wider area. Instead of settling lawsuits, it created more from a broader area. In 1907, the Supreme Court gave Georgia the power to rid itself of the smoke by injunction. An injunction would have probably meant the end to mining which would have killed the Basin economically. Mining engineers proposed the idea of condensing the gases to produce sulfuric acid. Georgia officials agreed to wait and see if the new process would help the situation. Successful versions of the acid plants were built a year later in Isabella and Copperhill.
In total, about 32 thousand acres were denuded by the smelter fumes. The first replacement trees were planted in 1939 through a joint effort by the Tennessee Copper Company and the TVA (Tennessee Valley Authority). The first plans to restore the ruined Copper Basin were announced in 1945. As of 1984, more than 14 million trees had been planted, many of them Black Locust and Japanese Fleeceflower. A variety of grasses, including Love Grass, were planted extensively. In some areas, our most famous ground cover, Kudzu, gained a foothold.
Replanting during the 1980's cost about $3,400 per acre in Tennessee. At the same time, Georgia was planting Loblolly Pines at a cost of about $625 per acre. Today, some planting is still being done by hand, but aerial reclamation is used extensively. Each acre receives about 500 pounds of fertilizer and 75 pounds of acid-tolerable plant seed at a cost of about $210 per acre.
Since the closing of the mines in 1987, most structures, including headframes, have been dismantled and the mines have been capped. Much of the land had been divided and auctioned off. The Burra Burra Mine site and the land surrounding the Central Mine (including the headframe) have been donated to the Ducktown Basin Museum. A visit to this museum is well worth the time and provides a good education in the local mining history.
With the end of mining also came the end to the pumping of water from the mines. Water levels have risen, causing widespread collapse of the surface. Large cracks have opened in many areas. The old cemetery at Mary Mine has been "swallowed up". At several sites, it is questionable whether the ground will support the weight of a vehicle. It is dangerous to travel off the main roads.
The problem of collapse is a local one. Erosion and contamination is a bigger environmental dilemma. Potato Creek, the largest stream draining the Basin, carries huge amounts of silt. The silt is building up behind the TVA dams in the Ocoee River Gorge. This material threatens to fill in the reservoirs. A dam has been constructed on Potato Creek in order to trap the silt before it enters the Ocoee River. This is a short term solution. The area behind the Potato Creek Dam will rapidly fill with silt.
The Ocoee River is, for the most part, devoid of fish and most forms of aquatic life. The water quality in the Basin and the Gorge has been impaired due to acid and metal contamination. The re-vegetation project will lessen erosion and silting to a great extent when it is completed. About 40 acres have been set aside to be preserved in its present state. Although the silting problem may have an answer, the water contamination is another story. Ground water, carrying acids and metals, will continue to seep into the streams. This environmental nightmare may never end.
Barclay, R. E., The Copper Basin, l890-1963. 1975; Barclay, R.E., Ducktown Back in Raht's Time, 1974; Ducktown Basin Museum, Burra Burra Historic Mine Site, Ducktown Basin Museum, 1992; Copper Basin, Commemorative Calendar; Emmons, W. H. and Laney F.B., Geology and Ore Deposits of the Ducktown Mining District. Tennessee, 1926; Polk County Publishing, A Tribute to the Miners; Quin, M.L., Tennessee's Copper Basin: A Case For Preserving an Abused Landscape, 1988; Rush, Ken, Curator, Ducktown Basin Museum; Soil Conservation Service, Tennessee Chemical Company; Tennessee Valley Authority, A Cooperative Erosion Control Plan for the Copper Basin, Polk County, Tennessee.
Copyright © Georgia Mineral Society, Inc.