Chalcopyrite (copper)

What is chalcopyrite? Chalcopyrite is the ore of copper found in Tennessee. It is copper iron sulfide (CuFeS2) It has a hardness of 3.5-4 and a specific gravity of 4.1-4.3

Chalcopyrite is mined primarily for copper. (hardness 2.5-3; specific gravity 8.9
Where are they found geographically? Copper is found only in Polk County in southeast Tennessee

When were they deposited? The USGS explains that copper was deposited in the Proterozoic (Pre-Cambrian Period) from geothermal vents called “black smokers” which formed in the period 750-570 million years ago when the region was diverging plates. 
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Pennsylvanian
Mississippian
Devonian
Silurian
Ordovician
Cambrian
Proterozoic
What are copper's uses? The primary use of copper is for electrical wiring. It is also used in common alloys, brass (copper and zinc) and bronze (copper and tin) The Mineral Institute has a good history of the use of copper
History of the use of copper in Tennessee The Cherokee had mined and smelted copper from Polk County.  In 1843, shortly after the Cherokee were relocated in 1838 , white settlers to the area discovered the copper.

 Mining started in 1847 and was expanded and consolidated for nearly 140 years.  Several histories of copper mining in Tennessee are available on the web.  “Minerals and mining of the Copper Basin” by Kim Cochran

At the start the operation was mostly mining, but after a processing plant was opened more and more of the ore was imported. In addition to mining copper, zinc and iron were also mined here. After sulfur pollution became a serious problem, the owners started producing sulfuric acid, and by the time operations ended in 1987, sulfuric acid was the most profitable product.

How is it mined and used? Chalcopyrite was mined both in surface pits and underground.

The processing of chalcopyrite to extract copper is complex, multi-step process. There are several sites which outline the process
Environmental consequences of chalcopyrite mining: The mining of chalcopyrite was devastating for Polk County and the surrounding areas. Releases of sulfur in the air killed much of the vegetation in the area. Cleanup started in the 1920's and continues today.

Abandoned mine in Polk County. Photo by USGS