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As with many natural resources, the total amount of copper on Earth is vast, with around 10 14 tons in the top kilometer of Earth's crust, which is about 5 million years' worth at the current rate of extraction. However, only a tiny fraction of these reserves is economically viable with present-day prices and technologies.
Native copper is an uncombined form of copper that occurs as a natural mineral. Copper is one of the few metallic elements to occur in native form, although it most commonly occurs in oxidized states and mixed with other elements. Native copper was an important ore of copper in historic times and was used by pre-historic peoples.
The same deposits of native copper on the Keweenaw Peninsula and Isle Royale were later mined commercially. From 1845 until 1887, the Michigan Copper Country was the leading producer of copper in the United States. Masses of native copper weighing hundreds of tons were sometimes found in the mines.
As a natural element in the Earth's crust, copper exists in most of the world's surface water and groundwater, although the actual concentration of copper in natural waters varies geographically. Drinking water can comprise 20–25% of dietary copper. [64]
World Book Encyclopedia, Exploring Earth. HyperPhysics, Georgia State University, Abundance of Elements in Earth's Crust. Eric Scerri, The Periodic Table, Its Story and Its Significance, Oxford University Press, 2007 "EarthRef.org Digital Archive (ERDA) -- Major Element Composition of the Core vs the Bulk Earth". earthref.org
The copper cycle is the biogeochemical cycle of natural and anthropogenic exchanges of copper between reservoirs in the hydrosphere, atmosphere, biosphere, and lithosphere. Human mining and extraction activities have exerted large influence on the copper cycle.
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The standard atomic weight of a chemical element (symbol A r °(E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element weighted by each isotope's abundance on Earth. For example, isotope 63 Cu (A r = 62.929) constitutes 69% of the copper on Earth, the rest being 65 Cu (A r = 64.927), so