CopperCopper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity. Pure copper is rather soft and malleable and a freshly-exposed surface has a pinkish or peachy color...
, as
native copper, is one of the few
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
lic
elementA chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons.Common examples of elements...
s to occur in uncombined form as a natural
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
, although most commonly occurs in oxidized states and mixed with other elements. Native copper was an important
oreAn ore is a type of rock that contains minerals such as gemstones or metals that can be extracted through mining and refined for use. Samples of ore in the form of exceptionally beautiful crystals, exotic layering visible when sectioned or polished or metallic presentations such as large nuggets or...
of copper in historic times and was used by pre-historic peoples.
Native copper occurs as rarely isometric cubic and octahedral crystals, but more typically as irregular masses and fracture fillings.
CopperCopper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity. Pure copper is rather soft and malleable and a freshly-exposed surface has a pinkish or peachy color...
, as
native copper, is one of the few
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
lic
elementA chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons.Common examples of elements...
s to occur in uncombined form as a natural
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
, although most commonly occurs in oxidized states and mixed with other elements. Native copper was an important
oreAn ore is a type of rock that contains minerals such as gemstones or metals that can be extracted through mining and refined for use. Samples of ore in the form of exceptionally beautiful crystals, exotic layering visible when sectioned or polished or metallic presentations such as large nuggets or...
of copper in historic times and was used by pre-historic peoples.
Native copper occurs as rarely isometric cubic and octahedral crystals, but more typically as irregular masses and fracture fillings. It has a reddish, orangish, and/or brownish color on fresh surfaces, but typically is
weatheredWeathering is the decomposition of Earth's rocks, soils and minerals through direct contact with the planet's atmosphere. Weathering occurs in situ, or "with no movement", and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice,...
and coated with a green
tarnishTarnish is a layer of corrosion that forms over copper, brass, silver, aluminum, and other semi-reactive metals as they undergo oxidation. It is analogous to rust, but with a slower rate of occurrence. Tarnish is mainly caused by chemicals in the air, such as sulfur...
of
copper(II) carbonateCopper carbonate is a blue-green compound forming part of the verdigris patina one sees on weathered brass, bronze, and copper...
(also known as
patinaPatina is a film on the surface of bronze or similar metals ; a sheen on wooden furniture produced by age, wear, and polishing; or any such acquired change of a surface through age and exposure...
or
verdigrisVerdigris is the common name for the green coating or patina formed when copper, brass or bronze is weathered and exposed to air or seawater over a period of time. It is usually a basic copper carbonate, but near the sea will be a basic copper chloride...
). Its specific gravity is 8.9 and its hardness is 2.5-3.
The mines of the Keweenaw native copper deposits of
Upper MichiganThe Upper Peninsula of Michigan is the northern of the two major land masses that comprise the U.S. state of Michigan. It is commonly referred to as the Upper Peninsula, the U.P., or Upper Michigan. More casually it is known as the land "above the Bridge"...
were major copper producers in the 19th and early 20th centuries, and are the largest deposits of native copper in the world. Native Americans mined copper on a small scale, and evidence exists of copper trading routes throughout North America among native peoples, proven by isotopic analysis. The first commercial mines in the
Keweenaw PeninsulaThe Keweenaw Peninsula is the northern-most part of Michigan's Upper Peninsula. It projects into Lake Superior and was the site of the first copper boom in the United States...
(which is nicknamed the "
Copper CountryThe Copper Country is an area in the Upper Peninsula of Michigan in the United States, including all of Keweenaw County, Michigan and most of Houghton, Baraga and Ontonagon counties. The area is so named as copper mining was prevalent there from 1845 until the late 1960s, with one mine ...
" and "
Copper IslandCopper Island is a local name given to the northern part of the Keweenaw Peninsula , separated from the rest of the Keweenaw Peninsula by Portage Lake and the Keweenaw Waterway.- Geography :The area was "isolated" by dredging in 1859 and construction in the...
)", opened in the 1840s.
Isle RoyaleIsle Royale is an island of the Great Lakes, located in the northwest of Lake Superior. The island and the 400 surrounding smaller islands and waters make up Isle Royale National Park. It is , with a long "I" in Isle and the accent on the first syllable of Royale, not the second...
in western Lake Superior was also a site of many tons of native copper. Some of it was extracted by native peoples, but only one of several commercial attempts at mining turned a profit there.
Another major native copper deposit is in Corocoro,
BoliviaBolivia, officially Plurinational State of Bolivia , is a landlocked country in central South America. It is bordered by Brazil to the north and east, Paraguay and Argentina to the south, and Chile and Peru to the west....
.
The name copper comes from the
GreekGreek , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical...
kyprios, of
CyprusCyprus , officially the Republic of Cyprus , is a Eurasian island country situated in the eastern Mediterranean, south of Turkey and west of Syria and Lebanon....
, the location of copper mines since pre-historic times.
Further reading
- Thurner, Arthur W. Strangers and Sojourners - A History of Michigan's Keweenaw Peninsula (Detroit, Michigan, U.S.A.: Wayne State University Press, 1994) ISBN 0814323960.B