Native copper is an uncombined form of

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

that occurs as a natural

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

. Copper is one of the few

metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...

lic elements to occur in native form, although it most commonly occurs in

oxidized Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

states and mixed with other elements. Native copper was an important ore used by pre-historic peoples. The name copper comes from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''kyprios'', "of

Cyprus Cyprus (), officially the Republic of Cyprus, is an island country in the eastern Mediterranean Sea. Situated in West Asia, its cultural identity and geopolitical orientation are overwhelmingly Southeast European. Cyprus is the List of isl ...

", the location of native copper mines since pre-historic times. Native copper typically occurs as irregular masses and fracture fillings, and rarely as isometric cubic and octahedral crystals. It has a reddish, orangish, and/or brownish color on fresh surfaces, but typically is weathered to a state of

verdigris Verdigris () is a common name for any of a variety of somewhat toxic copper salt (chemistry), salts of acetic acid, which range in colour from green to a blue-green, bluish-green depending on their chemical composition.H. Kühn, Verdigris and Cop ...

and coated with a green or blue-green

tarnish Tarnish is a thin layer of corrosion that forms over copper, brass, aluminum, magnesium, neodymium and other similar metals as their outermost layer undergoes a chemical reaction. Tarnish does not always result from the sole effects of oxygen in ...

patina Patina ( or ) is a thin layer that variously forms on the surface of copper, brass, bronze, and similar metals and metal alloys ( tarnish produced by oxidation or other chemical processes), or certain stones and wooden furniture (sheen prod ...

of copper(II) carbonate. Its

specific gravity Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

is 8.9 and

Mohs hardness The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...

is 2.5–3. The mines of the Keweenaw native copper deposits of Upper Michigan were major copper producers in the 19th and early 20th centuries, and are the largest deposits of native copper in the world. (Web archive; click cancel when it asks for authentication.) Native Americans mined copper on a small scale at this and many other locations, and evidence using isotopic analysis exists of copper trading routes throughout North America among native peoples. The first commercial mines in the

Keweenaw Peninsula The Keweenaw Peninsula (, ) is a peninsula of the U.S. state of Michigan. Part of the greater landmass of the Upper Peninsula of Michigan, Upper Peninsula, the Keweenaw Peninsula projects about northeasterly into Lake Superior, forming Keweena ...

(nicknamed the " Copper Country" and " Copper Island") opened in the 1840s. Isle Royale in western

Lake Superior Lake Superior is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. Lake Michigan–Huron has a larger combined surface area than Superior, but is normally considered tw ...

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. A geological record of native copper being dragged by a

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

and deposited on the west branch of the Ontonagon River up river from Lake Superior is seen in the Ontonagon Boulder in the possession of the Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution. Another major native copper deposit is in Coro Coro, Bolivia.

Gallery

File:Copper-20856.jpg, Dendritic native copper covered in

from

Broken Hill, New South Wales Broken Hill is a city in the Far West (New South Wales), far west region of outback New South Wales, Australia. An inland mining city, it is near the border with South Australia on the crossing of the Barrier Highway (A32) and the Silver City Hi ...

, Australia (6.5 cm) File:Copper-130051.jpg, Native copper cementing host rock, Ray Mine, Arizona (11.5 x 7.4 x 0.7 cm) File:Copper-20862.jpg, Dendritic native copper from the Itauz Mine,

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...

(8 x 3 x 1.5 cm) File:Copper-18705.jpg,

Tsumeb Tsumeb (; ) is a city of around 35,000 inhabitants and the largest town in the Oshikoto Region, Oshikoto region in northern Namibia. Tsumeb, since its founding in 1905, has been primarily a mining town. The town is the site of a deep mine (the ...

, Namibia (3 x 1.3 x 0.5 cm) File:Copper-Gypsum-177370.jpg, Dendritic native copper encased in transparent

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk ...

, Mission Mine,

Pima County, Arizona Pima County ( ) is a County (United States), county in the south central region of the U.S. state of Arizona, one of 15 List of counties in Arizona, counties in the state. As of the 2020 United States census, 2020 census, the population was 1 ...

, US (9.9 x 4.2 x 1.1 cm) File:Copper-Silver-39566.jpg, "Halfbreed" copper-silver nugget,

Keweenaw County, Michigan Keweenaw County (, ) is a County (United States), county in the western Upper Peninsula of the U.S. state of Michigan. As of the 2020 United States census, 2020 census, the county's population was 2,046, making it Michigan's least populous coun ...

, US (8.3 x 4.6 x 2 cm) File:Native Copper from the Keweenaw Peninsula Michigan.jpg,

Michigan Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...

, US (6.4 cm) File:Miedź rodzima - Półwysep Keweenaw, stan Michigan, USA.jpg, Native copper with verdigris, Keweenaw Peninsula, Michigan, USA. (4.1 cm)

References

External links

{{commons category Native element minerals Copper Cubic minerals Minerals in space group 225

Gallery

See also

References

Further reading

External links