Copper
A variety of Copper Group
What is Copper?
Copper has a remarkable array of uses, from the construction of pipes to conducting electricity. The history of its usefulness in society dates back to the "New Stone Age," when humans made a slow transition from using stones to using metals. Copper is found and mined globally, with the largest mines currently in Chile.
Etymology & Origins
In the Roman era, copper was mined principally on Cyprus, the origin of the name of the metal, from aes сyprium (metal of Cyprus), later corrupted to сuprum (Latin). Coper (Old English) and copper were derived from this, the later spelling first used around 1530.
Uses & Applications
Copper was the first metal to be worked by humans, and was often added with tin to create bronze (hence, the Bronze Age). This metal is currently used in coins, guns, surgical instruments, construction, and industrial machinery. It is also a great conductor, making it valuable for electrical equipment. Chefs treasure copper kitchen equipment because of this metal's high heat transfer. Even after thousands of years, there is no sign that copper will lose its usefulness anytime soon.
Healing Properties
Copper has long been associated with the relief of inflammation and pain and is worn by many arthritis sufferers. It is believed that the metal allows the positive energies in the body to flow freely for healing. Many believe that it stimulates motivation and hope. It works on the Base and Sacral chakras to balance the energies of sexual desire and metabolic changes within the body. When kept in the home, it is said to bring good luck to all.
Discover Values
This stone excels in popularity, cultural value.
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Associated Chakras
Key Characteristics
Characteristics of Copper
Copper, silver, and gold are in group 11 of the periodic table; these three metals have one s-orbital electron on top of a filled d-electron shell and are characterized by high ductility, and electrical and thermal conductivity. The filled d-shells in these elements contribute little to interatomic interactions, which are dominated by the s-electrons through metallic bonds. Unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of copper. At the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is usually supplied in a fine-grained polycrystalline form, which has greater strength than monocrystalline forms. The softness of copper partly explains its high electrical conductivity (59.6×106 S/m) and high thermal conductivity, second highest (second only to silver) among pure metals at room temperature. This is because the resistivity to electron transport in metals at room temperature originates primarily from scattering of electrons on thermal vibrations of the lattice, which are relatively weak in a soft metal. The maximum permissible current density of copper in open air is approximately 3.1×106 A/m² of cross-sectional area, above which it begins to heat excessively. Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air. The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells corresponds to orange light. As with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. Copper does not react with water, but it does slowly react with atmospheric oxygen to form a layer of brown-black copper oxide which, unlike the rust that forms on iron in moist air, protects the underlying metal from further corrosion (passivation). A green layer of verdigris (copper carbonate) can often be seen on old copper structures, such as the roofing of many older buildings and the Statue of Liberty. Copper tarnishes when exposed to some sulfur compounds, with which it reacts to form various copper sulfides.
Formation of Copper
Copper is produced in massive stars and is present in the Earth's crust in a proportion of about 50 parts per million (ppm). In nature, copper occurs in a variety of minerals, including native copper, copper sulfides such as chalcopyrite, bornite, digenite, covellite, and chalcocite, copper sulfosalts such as tetrahedite-tennantite, and enargite, copper carbonates such as azurite and malachite, and as copper(I) or copper(II) oxides such as cuprite and tenorite, respectively. The largest mass of elemental copper discovered weighed 420 tonnes and was found in 1857 on the Keweenaw Peninsula in Michigan, US. Native copper is a polycrystal, with the largest single crystal ever described measuring 4.4×3.2×3.2 cm.
Health & Safety Information
- ⚠️Gram quantities of various copper salts have been taken in suicide attempts and produced acute copper toxicity in humans, possibly due to redox cycling and the generation of reactive oxygen species that damage DNA. Corresponding amounts of copper salts (30 mg/kg) are toxic in animals. A minimum dietary value for healthy growth in rabbits has been reported to be at least 3 ppm in the diet. However, higher concentrations of copper (100 ppm, 200 ppm, or 500 ppm) in the diet of rabbits may favorably influence feed conversion efficiency, growth rates, and carcass dressing percentages. Chronic copper toxicity does not normally occur in humans because of transport systems that regulate absorption and excretion. Autosomal recessive mutations in copper transport proteins can disable these systems, leading to Wilson's disease with copper accumulation and cirrhosis of the liver in persons who have inherited two defective genes. Elevated copper levels have also been linked to worsening symptoms of Alzheimer's disease.
Quick Facts
Physical Properties
- Color
- Red, tarnishes to black, green in air
- Hardness (Mohs)
- 2.5 - 3
- Density
- 8.93 g/cm³
- Streak
- Copper-red
- Luster
- Metallic
- Crystal System
- Isometric
Chemical Properties
- Chemical Formula
- Cu
- Elements
- Cu
Also Known As
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