200px|thumb|srebro rodzime, Meksyk
200px|thumb|srebro rodzime - [[skupienia minerałów|skupienie drutowe]]

'''Srebro rodzime''' - rzadko spotykany minerał z gromady pierwiastków rodzimych, w skład którego wchodzi głównie metaliczne srebro. 

Nazwa minerału pochodzi od greckiego określenia tego minerału - ''silbur'', a także od ''łac.argentum = biały''.

== Właściwości ==
*Wzór chemiczny:   '''Ag''' – srebro (Argentum)
*Układ krystalograficzny: regularny
*Barwa: srebrzystobiała, biała, szara, a wskutek utleniania czarna
*Rysa: srebrzystobiała, szara, błyszcząca
*Twardość: 2,5-3
*Gęstość: 9,6 -12
*Łupliwość: brak
*Przełam: haczykowaty
*Połysk: silny, metaliczny

Rzadko tworzy kryształy izomorficzne o postaci sześcianu lub ośmiościanu. Przeważnie występuje w skupieniach ziarnistych, blaszkowatych, płytkowych, włóknistych, kłębiastych. Często tworzy duże bryły (samorodki), wypryśnięcia, naloty. 

Jest izostrukturalne ze złotem i miedzią rodzimą, z którymi często tworzy naturalne stopy. 

Zawiera niekiedy znaczne domieszki: rtęci (amalgamaty), złota (elektrum), bizmutu (chilenit), antymonu (animikit), arsenu (huntilith), oraz miedzi i platyny.

== Występowanie ==

{{Elementbox_isotopes_decay2 | mn=105 | sym=Ag
 | na=syn | hl=41.2 d
 | dm1=ε | de1=- | pn1=105 | ps1=Pd
 | dm2=γ | de2=0.344, 0.280,<br /> 0.644, 0.443 | pn2=| ps2=- }}
{{Elementbox_isotopes_decay2 | mn=106m | sym=Ag
 | na=syn | hl=8.28 d
 | dm1=ε | de1=- | pn1=106 | ps1=Pd
 | dm2=γ | de2=0.511, 0.717,<br /> 1.045, 0.450 | pn2=| ps2=- }}

{{Elementbox_isotopes_decay3 | mn=108m | sym=Ag
 | na=syn | hl=418 y
 | dm1=ε | de1=- | pn1=108 | ps1=Pd
 | dm2=IT | de2=0.109 | pn2=108 | ps2=Ag 
 | dm3=γ | de3=0.433, 0.614,<br /> 0.722 | pn3=| ps3=-}}

{{Elementbox_isotopes_decay2 | mn=111 | sym=Ag
 | na=syn | hl=7.45 d
 | dm1=β<sup>-</sup> | de1=1.036, 0.694 | pn1=111 | ps1=Cd
 | dm2=γ | de2=0.342 | pn2=| ps2=- }}

'''Silver''' () is a chemical element with the symbol "'''Ag'''" (, from the Ancient Greek: ''ἀργήντος'' - argēntos, gen. of ''ἀργήεις'' - argēeis, "white, shining"  ) and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal. It occurs as a pure free metal (native silver) and alloyed with gold (electrum), as well as in various minerals, such as argentite and chlorargyrite. Most silver is produced as a by-product of copper, gold, lead, and zinc mining.

Silver has been known since ancient times and has long been valued as a precious metal, used to make ornaments, jewellery, high-value tableware and utensils (hence the term "silverware") and currency coins. Today, silver metal is used in electrical contacts and conductors, in mirrors and in catalysis of chemical reactions. Its compounds are used in photographic film and dilute solutions of silver nitrate and other silver compounds are used as disinfectants. Although the antimicrobial uses of silver have largely been supplanted by the use of antibiotics, further research into its clinical potential is in progress.

== Occurrence and extraction == 

thumb|left|Time trend of silver production
Silver is found in native form, alloyed with gold or combined with sulfur, arsenic, antimony or chlorine in ores such as argentite (Ag<sub>2</sub>S), horn silver (AgCl), and pyrargyrite (Ag<sub>3</sub>SbS<sub>3</sub>). The principal sources of silver are the ores of copper, copper-nickel, lead, and lead-zinc obtained from Peru, Mexico, China, Australia, Chile and Poland. Peru and Mexico have been mining silver since 1546 and are still major world producers. Top silver producing mines are Proano / Fresnillo, Cannington, Dukat, Uchucchacua and Greens Creek mine.<ref>[http://www.infomine.com/commodities/silver.asp Top silver producers]</ref> 

The metal can also be produced during the electrolytic refining of copper and by the application of the Parkes process on lead metal obtained from lead ores that contain small amounts of silver. Commercial-grade fine silver is at least 99.9% pure silver, and purities greater than 99.999% are available. In 2007, Peru was the world's top producer of silver, closely followed by Mexico, according to the British Geological Survey.

== Characteristics == 
thumb|left|A nugget of silver

Silver is a very ductile and malleable (slightly harder than polish. It has the highest electrical conductivity of all metals, even higher than copper, but its greater cost and tarnishability have prevented it from being widely used in place of copper for electrical purposes, though it was used in the electromagnets used for enriching uranium during World War II (mainly because of the wartime shortage of copper). Another notable exception is in high-end audio cables.

Among metals, pure silver has the highest photosensitive and are remarkable for their ability to record a developed chemically. Silver is stable in pure air and water, but tarnishes when it is exposed to air or water containing ozone or hydrogen sulfide. The most common oxidation state of silver is +1 (for example, silver nitrate: AgNO<sub>3</sub>); in addition, +2 compounds (for example, silver(II) fluoride: AgF<sub>2</sub>) and +3 compounds (for example, potassium tetrafluoroargentate: K[AgF<sub>4</sub>]) are known.

== Isotopes == 

Naturally occurring silver is composed of the two stable isotopes, <sup>107</sup>Ag and <sup>109</sup>Ag, with <sup>107</sup>Ag being the more abundant (51.839% natural abundance). Silver's standard atomic mass is 107.8682(2) u. 
Twenty-eight radioisotopes have been characterised, the most stable being <sup>105</sup>Ag with a half-life of 41.29 days, <sup>111</sup>Ag with a half-life of 7.45 days, and <sup>112</sup>Ag with a half-life of 3.13 hours.

All of the remaining radioactive isotopes have half-lives that are less than an hour, and the majority of these have half-lives that are less than 3 minutes. This element has numerous meta states, the most stable being <sup>108m</sup>Ag (''t''<sub>* </sub> 418 years), <sup>110m</sup>Ag (''t''<sub>* </sub> 249.79 days) and <sup>106m</sup>Ag (''t''<sub>* </sub> 8.28 days).

Isotopes of silver range in u (<sup>94</sup>Ag) to 123.929 u (<sup>124</sup>Ag). The primary decay mode before the most abundant stable isotope, <sup>107</sup>Ag, is electron capture and the primary mode after is beta decay. The primary decay products before <sup>107</sup>Ag are palladium (element 46) isotopes, and the primary products after are cadmium (element 48) isotopes.

The pallace Santa Clara meteorite in 1978. The discoverers suggest that the coalescence and differentiation of iron-cored small accretion of the solar system must reflect the presence of live short-lived nuclides in the early solar system.

== Silver compounds ==

Silver metal dissolves readily in silver soldering or annealing. However, silver reacts readily with sulfur or seed clouds to produce rain. battery) batteries. Silver carbonate  is precipitated when silver nitrate is treated with sodium carbonate . 
Silver fulminate , a powerful, touch-sensitive explosive used in percussion caps, is made by reaction of silver metal with nitric acid in the presence of ethanol . Another dangerously explosive silver compound is silver azide , formed by reaction of silver nitrate with sodium azide, .
Latent images formed in silver halide crystals are developed by treatment with alkaline solutions of reducing agents such as hydroquinone, metol (4-(methylamino)phenol sulfate) or ascorbate which reduce the exposed halide to silver metal. Alkaline solutions of silver nitrate can be reduced to silver metal by reducing sugars such as glucose, and this reaction is used to silver glass mirrors and the interior of glass Christmas ornaments. Silver halides are soluble in solutions of sodium thiosulfate  which is used as a photographic fixer, to remove excess silver halide from photographic emulsions after image development. Silver metal is attacked by strong oxidisers such as potassium permanganate and potassium dichromate , and in the presence of potassium bromide  these compounds are used in photography to bleach silver images, converting them to silver halides that can either be fixed with thiosulfate or re-developed to intensify the original image. Silver forms cyanide complexes silver cyanide that are soluble in water in the presence of an excess of cyanide ions. Silver cyanide solutions are used in electroplating of silver.

== Applications == 

thumb|right|240px|A [[China|Chinese gilt-silver cup with flower design]]
=== As a precious metal ===
A major use of silver is as a Argentium Sterling Silver is formed, with improved properties including resistance to firescale.

Silver is used in medals, denoting second place. Some high-end musical instruments are made from sterling silver, such as the flute.

=== In dentistry ===
Silver dissolves in mercury to make amalgams that are widely used for dental fillings. To make dental amalgam, a mixture of powdered silver and other metals is mixed with mercury to make a stiff paste that can be moulded into shape in a cavity, but which sets hard within a few hours. However, there is increasing evidence that the mercury in such amalgams may be absorbed by the body and cause various deleterious effects, including neurotoxicity.

=== In photography and electronics ===
Photography used 24% of the silver consumed in 2001 in the form of halides, while 33% was used in jewellery, 40% for industrial uses, and only 3% for coins and medals.<ref>Butterman, WC & Hilliard, HE (2005) Silver. Open file report 2004-1251. US Geological Survey mineral commodity profiles, Reston, Virginia. </ref>

Some electrical and electronic products use silver for its superior conductivity, even when tarnished. For example, printed circuits are made using silver paints,<ref name=lanl>DACs, arcing. 

thumb|Silver output in 2005
thumb|left|Silver ore (Lincoln cent is shown for scale)
thumb|left|Silver leaf on andesite rock

=== In solder and brazing ===
Silver is also used to make silver-zinc and silver-cadmium batteries. Silver in a thin layer on top of a bearing material can provide a significant increase in galling resistance and reduce wear under heavy load, particularly against steel.

=== In mirrors and optics ===
Mirrors which need superior reflectivity for visible light are made with silver as the reflecting material in a process called silvering, though common mirrors are backed with aluminium. Using a process called sputtering, silver (and sometimes gold) can be applied to glass at various thicknesses, allowing different amounts of light to penetrate. Silver is usually reserved for coatings of specialised optics, and the silvering most often seen in architectural glass and tinted windows on vehicles is produced by sputtered aluminium, which is cheaper and less susceptible to tarnishing and corrosion.

=== In nuclear reactors ===

Because silver readily absorbs free fission chain reaction in pressurized water nuclear reactors, generally in the form of an alloy containing 80% silver, 15% indium, and 5% cadmium.

=== As a catalyst ===
Silver's catalytic properties make it ideal for use as a catalyst in oxidation reactions, for example, the production of formaldehyde from methanol and air by means of silver screens or crystallites containing a minimum 99.95&nbsp;weight-percent silver. Silver (upon some suitable support) is probably the only catalyst available today to convert ethylene to ethylene oxide (later hydrolyzed to ethylene glycol, used for making polyesters)—a very important industrial reaction.

membranes of only a few monolayers thickness. Such a membrane could be used to filter pure oxygen from air.

=== As money ===
Silver, in the form of ISO currency code XAG. 

The name of the United Kingdom monetary unit "pound" reflects the fact that it originally represented the value of one troy pound of sterling silver. 

In the 1800s, many nations, such as the United States and Great Britain, switched from silver to a gold standard of monetary value, then in the 20th century to fiat currency.

=== In medicine === 
Silver ions and silver compounds show a toxic effect on some bacteria, viruses, algae and fungi, typical for heavy metals like lead or mercury, but without the high toxicity to humans that is normally associated with them. Its germicidal effects kill many microbial organisms ''in vitro''. 

Hippocrates, the father of modern medicine, wrote that silver had beneficial healing and anti-disease properties, and the Phoenicians used to store water, wine, and vinegar in silver bottles to prevent spoiling. In the early 1900s people would put silver dollars in milk bottles to prolong the milk's freshness. Its germicidal effects increase its value in utensils and as jewellery. The exact process of silver's germicidal effect is still not well understood, although theories exist. One of these is the oligodynamic effect, which explains the effect on microbial lifeforms but does not explain certain antiviral effects.

Silver compounds were used successfully to prevent infection in World War I before the advent of antibiotics. Silver nitrate solution was a standard of care but was largely replaced by silver sulfadiazine cream (SSD Cream),<ref></ref> which was generally the "standard of care" for the antibacterial and antibiotic treatment of serious burns until the late 1990s. Now, other options, such as silver-coated dressings (activated silver dressings), are used in addition to SSD cream and may present advantages such as pain reduction and capacity for treatment at home. 

The widespread use of silver went out of fashion with the development of modern antibiotics. However, recently there has been renewed interest in silver as a broad-spectrum antimicrobial. In particular, silver is being used with burn victims. In 2007, AGC Flat Glass Europe introduced the first antibacterial glass to fight hospital-caught infection: it is covered with a thin layer of silver.<ref></ref>  In addition, Kohler has introduced a line of endotracheal breathing tube with a fine coat of silver for use in mechanical ventilation, after studies found it reduced the risk of ventilator-associated pneumonia.<ref name="FDA Silver"></ref>

==== As a medication ====
Today, various kinds of silver compounds, or devices to make solutions or colloids containing silver, are sold as remedies for a wide variety of diseases. Although most colloidal silver preparations are harmless, some people using these home-made solutions excessively have developed argyria over a period of months or years. Several cases have been documented in medical literature, including one case of coma associated with high intake of silver.

Silver is widely used in topical gels and impregnated into bandages because of its wide-spectrum antimicrobial activity. The anti-microbial properties of silver stem from the chemical properties of its ionized form, Ag<sup>+</sup>. This ion forms strong molecular bonds with other substances used by bacteria to respire, such as molecules containing sulfur, nitrogen, and oxygen.<ref></ref> Once the Ag<sup>+</sup> ion complexes with these molecules, they are rendered unusable by the bacteria, depriving it of necessary compounds and eventually leading to the bacteria's death.

=== In food === 
In India, foods, especially sweets, can be found decorated with a thin layer of silver known as vark. Silver as a food additive is given the E number E174 and is classed as a food coloring. It is used solely for external decoration, such as on chocolate confectionery, in the covering of dragées and the decoration of sugar-coated flour confectionery. In Australia, it is banned as a food additive.

=== In clothing === 
thumb|right|240px|Goddess [[Minerva on a Roman silver plate, 1st century BCE]]
Silver inhibits the growth of fungi. It keeps odour to a minimum and reduces the risk of bacterial and fungal infection. In clothing, the combination of silver and moisture movement (wicking) may help to reduce the harmful effects of prolonged use in active and humid conditions.

Silver is used in clothing in two main forms:
* A form in which silver ions are integrated into the polymer from which yarns are made (a form of nanotechnology) 
* A form in which the silver is physically coated onto the yarns. 
In both cases the silver prevents the growth of a broad spectrum of bacteria and fungi. 

Recorded use of silver to prevent infection dates to Rome. It was rediscovered in the Middle Ages, where it was used for several purposes, such as to disinfect water and food during storage, and also for the treatment of burns and wounds as wound dressing. In the 19th century, sailors on long ocean voyages would put silver coins in barrels of water and wine to keep the liquid pure. Pioneers in America used the same idea as they made their journey from coast to coast.
Silver solutions were approved in the 1920s by the US Food and Drug Administration for use as antibacterial agents. Today, wound dressings containing silver are well established for clinical wound care and have recently been introduced in consumer products such as sticking plasters.<ref>[http://www.americanelements.com/agnp.html Silver in Textiles and Clothing]</ref>