Gold Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! == Other applications == === Jewelry === [[File:MocheGoldNecklace.jpg|thumb|[[Moche (culture)|Moche]] gold necklace depicting feline heads. [[Larco Museum]] Collection, [[Lima, Peru]].]] [[File:Boule de Genève, ca. 1890.jpeg|thumb|A 21.5k yellow gold pendant [[watch]] so-called "[[Boule de Genève]]" (Geneva ball), {{Circa|1890}}.]] Because of the softness of pure (24k) gold, it is usually [[alloy]]ed with other metals for use in jewelry, altering its hardness and ductility, melting point, color and other properties. Alloys with lower [[fineness#Karat|karat rating]], typically 22k, 18k, 14k or 10k, contain higher percentages of copper, silver, palladium or other base metals in the alloy.<ref name="utilisegold">[https://web.archive.org/web/20080619061619/http://www.utilisegold.com/jewellery_technology/colours/colour_alloys/ Jewellery Alloys]. World Gold Council</ref><!--Is there a better ref?--> Nickel is toxic, and its release from nickel white gold is controlled by legislation in Europe.<ref name="utilisegold" /> Palladium-gold alloys are more expensive than those using nickel.<ref>{{Cite book |url=https://books.google.com/books?id=W_hTAAAAMAAJ |title=Professional goldsmithing: a contemporary guide to traditional jewelry techniques |last=Revere |first=Alan |date=1 May 1991 |publisher=Van Nostrand Reinhold |isbn=978-0-442-23898-8}}</ref> High-karat white gold alloys are more resistant to corrosion than are either pure silver or [[sterling silver]]. The Japanese craft of [[Mokume-gane]] exploits the color contrasts between laminated colored gold alloys to produce decorative wood-grain effects. By 2014, the gold jewelry industry was escalating despite a dip in gold prices. Demand in the first quarter of 2014 pushed turnover to $23.7 billion according to a [[World Gold Council]] report. Gold [[solder]] is used for joining the components of gold jewelry by high-temperature hard soldering or [[brazing]]. If the work is to be of [[hallmark]]ing quality, the gold solder alloy must match the fineness of the work, and alloy formulas are manufactured to color-match yellow and white gold. Gold solder is usually made in at least three melting-point ranges referred to as Easy, Medium and Hard. By using the hard, high-melting point solder first, followed by solders with progressively lower melting points, goldsmiths can assemble complex items with several separate soldered joints. Gold can also be made into [[gold thread|thread]] and used in [[embroidery]]. === Electronics === Only 10% of the world consumption of new gold produced goes to industry,<ref name="oil-price.com-worlds-gold-consumption 2011" /> but by far the most important industrial use for new gold is in fabrication of corrosion-free [[electrical connectors]] in computers and other electrical devices. For example, according to the World Gold Council, a typical cell phone may contain 50 mg of gold, worth about 2 dollars 82 cents. But since nearly one billion cell phones are produced each year, a gold value of US$2.82 in each phone adds to US$2.82 billion in gold from just this application.<ref>[http://www.usfunds.com/slideshows/the-many-uses-of-gold/ Uses of gold] {{Webarchive|url=https://archive.today/20141104233515/http://www.usfunds.com/slideshows/the-many-uses-of-gold/ |date=4 November 2014 }} Accessed 4 November 2014</ref> (Prices updated to November 2022) Though gold is attacked by free chlorine, its good conductivity and general resistance to oxidation and corrosion in other environments (including resistance to non-chlorinated acids) has led to its widespread industrial use in the electronic era as a thin-layer coating on [[electrical connector]]s, thereby ensuring good connection. For example, gold is used in the connectors of the more expensive electronics cables, such as audio, video and [[USB]] cables. The benefit of using gold over other connector metals such as [[tin]] in these applications has been debated; gold connectors are often criticized by audio-visual experts as unnecessary for most consumers and seen as simply a marketing ploy. However, the use of gold in other applications in electronic sliding contacts in highly humid or corrosive atmospheres, and in use for contacts with a very high failure cost (certain [[computer]]s, communications equipment, [[spacecraft]], [[jet aircraft]] engines) remains very common.<ref>{{cite book |editor-last=Krech III |editor-first=Shepard |editor2-last=Merchant |editor2-first=Carolyn |editor3-last=McNeill |editor3-first=John Robert |title=Encyclopedia of World Environmental History |volume=2: F–N |year=2004 |publisher=Routledge |isbn=978-0-415-93734-4 |pages=597– |url={{google books |plainurl=y |id=G7JrhAy5phoC |page=597}} }}</ref> Besides sliding electrical contacts, gold is also used in [[electrical contacts]] because of its resistance to [[corrosion]], [[electrical conductivity]], [[ductile|ductility]] and lack of [[toxicity]].<ref>{{cite web |title=General Electric Contact Materials |website=Electrical Contact Catalog (Material Catalog) |publisher=Tanaka Precious Metals |date=2005 |url=http://www.tanaka-precious.com/catalog/material.html|archive-url=https://web.archive.org/web/20010303213152/http://www.tanaka-precious.com/catalog/material.html|url-status=dead|archive-date=3 March 2001 |access-date=21 February 2007}}</ref> Switch contacts are generally subjected to more intense corrosion stress than are sliding contacts. Fine gold wires are used to connect [[semiconductor device]]s to their packages through a process known as [[wire bonding]]. The concentration of free electrons in gold metal is 5.91×10<sup>22</sup> cm<sup>−3</sup>.<ref>{{Cite book |url=https://books.google.com/books?id=MaWKDQAAQBAJ&pg=SA2-PA8 |title=Electronic, Magnetic, and Optical Materials, Second Edition |last1=Fulay |first1=Pradeep |last2=Lee |first2=Jung-Kun |date=2016 |publisher=CRC Press |isbn=978-1-4987-0173-0}}</ref> Gold is highly [[electrical conductivity|conductive]] to electricity and has been used for [[electrical wiring]] in some high-energy applications (only silver and copper are more conductive per volume, but gold has the advantage of corrosion resistance). For example, gold electrical wires were used during some of the [[Manhattan Project]]'s atomic experiments, but large high-current silver wires were used in the [[calutron]] isotope separator magnets in the project. It is estimated that 16% of the world's presently-accounted-for gold and 22% of the world's silver is contained in electronic technology in Japan.<ref>{{cite news |url=http://www.techradar.com/news/phone-and-communications/mobile-phones/japan-wants-citizens-to-donate-their-phone-to-make-2020-olympic-medals-1326938 |title=Japan wants citizens to donate their old phone to make 2020 Olympics medals |work=TechRadar |date=23 August 2016 |author=Peckham, James}}</ref> === Medicine === Metallic and gold compounds have long been used for medicinal purposes. Gold, usually as the metal, is perhaps the most anciently administered medicine (apparently by shamanic practitioners)<ref>{{cite journal |doi=10.1007/s10787-007-0021-x |title=Clinical pharmacology of gold |date=2008 |last1=Kean |first1=W. F. |last2=Kean |first2=I. R. L. |journal=Inflammopharmacology |volume=16 |issue=3 |pages=112–25 |pmid=18523733|s2cid=808858 }}</ref> and known to [[Dioscorides]].<ref>{{cite book |last1=Moir |first1=David Macbeth |url=https://archive.org/details/b21364047 |page=[https://archive.org/details/b21364047/page/225 225] |title=Outlines of the ancient history of medicine |publisher=William Blackwood |date=1831}}</ref><ref>Mortier, Tom. [https://lirias.kuleuven.be/bitstream/1979/254/2/thesis_finaal.pdf An experimental study on the preparation of gold nanoparticles and their properties] {{Webarchive|url=https://web.archive.org/web/20131005015930/https://lirias.kuleuven.be/bitstream/1979/254/2/thesis_finaal.pdf |date=5 October 2013 }}, PhD thesis, University of Leuven (May 2006)</ref> In medieval times, gold was often seen as beneficial for the health, in the belief that something so rare and beautiful could not be anything but healthy. Even some modern [[esotericism|esotericists]] and forms of [[alternative medicine]] assign metallic gold a healing power. In the 19th century gold had a reputation as an [[anxiolytic]], a therapy for nervous disorders. [[Depression (mood)|Depression]], [[epilepsy]], [[migraine]], and glandular problems such as [[amenorrhea]] and [[impotence]] were treated, and most notably [[alcoholism]] (Keeley, 1897).<ref>{{Cite journal |last1=Richards |first1=Douglas G. |last2=McMillin |first2=David L. |last3=Mein |first3=Eric A. |last4=Nelson |first4=Carl D. |name-list-style=amp |title=Gold and its relationship to neurological/glandular conditions |journal=The International Journal of Neuroscience |volume=112 |issue=1 |pages=31–53 |date=January 2002 |pmid=12152404 |doi=10.1080/00207450212018|s2cid=41188687 }}</ref> The apparent paradox of the actual toxicology of the substance suggests the possibility of serious gaps in the understanding of the action of gold in physiology.<ref>{{cite journal |doi=10.1006/biol.1997.0123 |pmid=9637749 |title=Gold, the Noble Metal and the Paradoxes of its Toxicology |date=1998 |last1=Merchant |first1=B. |journal=Biologicals |volume=26 |pages=49–59 |issue=1}}</ref> Only salts and radioisotopes of gold are of pharmacological value, since elemental (metallic) gold is inert to all chemicals it encounters inside the body (e.g., ingested gold cannot be attacked by stomach acid). Some gold salts do have [[anti-inflammatory]] properties and at present two are still used as pharmaceuticals in the treatment of arthritis and other similar conditions in the US ([[sodium aurothiomalate]] and [[auranofin]]). These drugs have been explored as a means to help to reduce the pain and swelling of [[rheumatoid arthritis]], and also (historically) against [[tuberculosis]] and some parasites.<ref name="Messorri">{{Cite book |first1=L. |last1=Messori |first2=G. |last2=Marcon |chapter-url=https://books.google.com/books?id=wgifUs8dFbgC&pg=PA279 |chapter=Gold Complexes in the treatment of Rheumatoid Arthritis |title=Metal ions and their complexes in medication |editor-last=Sigel |editor-first=Astrid |publisher=CRC Press |date=2004 |isbn=978-0-8247-5351-1 |pages=280–301}}</ref> Gold alloys are used in [[restorative dentistry]], especially in tooth restorations, such as [[crown (dentistry)|crowns]] and permanent [[bridge (dentistry)|bridges]]. The gold alloys' slight malleability facilitates the creation of a superior molar mating surface with other teeth and produces results that are generally more satisfactory than those produced by the creation of porcelain crowns. The use of gold crowns in more prominent teeth such as incisors is favored in some cultures and discouraged in others. [[Colloidal gold]] preparations (suspensions of [[gold nanoparticle]]s) in water are intensely red-[[color]]ed, and can be made with tightly controlled particle sizes up to a few tens of nanometers across by reduction of gold chloride with [[citrate]] or [[ascorbate]] ions. Colloidal gold is used in research applications in medicine, biology and [[materials science]]. The technique of [[immunogold labeling]] exploits the ability of the gold particles to adsorb protein molecules onto their surfaces. Colloidal gold particles coated with specific antibodies can be used as probes for the presence and position of antigens on the surfaces of cells.<ref>{{Cite journal |doi=10.1016/0019-2791(71)90496-4 |pmid=4110101 |date=1971 |last1=Faulk |first1=W. P. |last2=Taylor |first2=G. M. |title=An immunocolloid method for the electron microscope |volume=8 |issue=11 |pages=1081–3 |journal=Immunochemistry}}</ref> In ultrathin sections of tissues viewed by [[electron microscope|electron microscopy]], the immunogold labels appear as extremely dense round spots at the position of the [[antigen]].<ref>{{Cite journal |pmid=6153194 |date=1980 |last1=Roth |first1=J. |last2=Bendayan |first2=M. |last3=Orci |first3=L. |title=FITC-protein A-gold complex for light and electron microscopic immunocytochemistry |volume=28 |issue=1 |pages=55–7 |journal=Journal of Histochemistry and Cytochemistry |doi=10.1177/28.1.6153194 |doi-access=free}}</ref> Gold, or alloys of gold and [[palladium]], are applied as conductive coating to biological specimens and other non-conducting materials such as plastics and glass to be viewed in a [[scanning electron microscope]]. The coating, which is usually applied by [[sputtering]] with an [[argon]] [[plasma (physics)|plasma]], has a triple role in this application. Gold's very high electrical conductivity drains [[electric charge|electrical charge]] to earth, and its very high density provides stopping power for electrons in the [[electron beam]], helping to limit the depth to which the electron beam penetrates the specimen. This improves definition of the position and topography of the specimen surface and increases the [[Angular resolution|spatial resolution]] of the image. Gold also produces a high output of [[secondary emission|secondary electrons]] when irradiated by an electron beam, and these low-energy electrons are the most commonly used signal source used in the scanning electron microscope.<ref>{{Cite book |last1=Bozzola |first1=John J. |last2=Russell |first2=Lonnie Dee |url=https://books.google.com/books?id=RqSMzR-IXk0C&pg=PA65 |page=65 |title=Electron microscopy: principles and techniques for biologists |name-list-style=amp |publisher=Jones & Bartlett Learning |date=1999 |isbn=978-0-7637-0192-5}}</ref> The isotope [[gold-198]] ([[half-life]] 2.7 days) is used in [[nuclear medicine]], in some [[cancer]] treatments and for treating other diseases.<ref>{{cite web |url=http://web.missouri.edu/~kattik/katti/katres.html |archive-url=https://web.archive.org/web/20090314121232/http://web.missouri.edu/~kattik/katti/katres.html |archive-date=14 March 2009 |title=Nanoscience and Nanotechnology in Nanomedicine: Hybrid Nanoparticles In Imaging and Therapy of Prostate Cancer |publisher=Radiopharmaceutical Sciences Institute, University of Missouri-Columbia}}</ref><ref>{{cite journal |doi=10.1211/jpp.60.8.0005 |title=Radiotherapy enhancement with gold nanoparticles |date=2008 |last1=Hainfeld |first1=James F. |last2=Dilmanian |first2=F. Avraham |last3=Slatkin |first3=Daniel N. |last4=Smilowitz |first4=Henry M. |s2cid=32861131 |journal=Journal of Pharmacy and Pharmacology |volume=60 |issue=8 |pages=977–85 |pmid=18644191 }}</ref> === Cuisine === [[Image:Cake with pure gold (3038005040).jpg|thumb|Cake with gold decoration served at the [[Amstel Hotel]], [[Amsterdam]] ]] * Gold can be used in food and has the [[E number]] 175.<ref name="FSA">{{Cite news |url=http://www.food.gov.uk/safereating/chemsafe/additivesbranch/enumberlist |title=Current EU approved additives and their E Numbers |date=27 July 2007 |publisher=Food Standards Agency, UK}}</ref> In 2016, the [[European Food Safety Authority]] published an opinion on the re-evaluation of gold as a food additive. Concerns included the possible presence of minute amounts of gold [[nanoparticle]]s in the food additive, and that gold nanoparticles have been shown to be [[genotoxic]] in mammalian cells [[in vitro]].<ref>{{cite journal |title=Scientific Opinion on the re-evaluation of gold (E 175) as a food additive |journal=EFSA Journal |volume=14 |issue=1 |year=2016 |issn=1831-4732 |doi=10.2903/j.efsa.2016.4362 |page=4362|doi-access=free}}</ref> * [[Gold leaf]], flake or dust is used on and in some gourmet foods, notably sweets and drinks as decorative ingredient.<ref>{{cite web |title=The Food Dictionary: Varak |publisher=Barron's Educational Services, Inc. |date=1995 |url=http://www.epicurious.com/cooking/how_to/food_dictionary/entry?id=5061 |archive-url=https://web.archive.org/web/20060523014547/http://www.epicurious.com/cooking/how_to/food_dictionary/entry?id=5061 |archive-date=23 May 2006 |access-date=27 May 2007}}</ref> Gold flake was used by the nobility in [[medieval Europe]] as a decoration in food and drinks,<ref>{{Cite book |url=https://books.google.com/books?id=OMLuBQAAQBAJ&pg=PT94 |title=Commensality: From Everyday Food to Feast |last1=Kerner |first1=Susanne |last2=Chou |first2=Cynthia |last3=Warmind |first3=Morten |page=94 |date=2015 |publisher=Bloomsbury Publishing |isbn=978-0-85785-719-4}}</ref> * Danziger Goldwasser (German: Gold water of Danzig) or [[Goldwasser]] ({{lang-en|Goldwater}}) is a traditional German herbal [[liqueur]]<ref>{{Cite book |chapter-url=https://books.google.com/books?id=tsUNAAAAYAAJ&pg=PA101 |title=Deutschland nebst Theilen der angrenzenden Länder |chapter=Danzig |first=Karl |last=Baedeker |date=1865 |publisher=Karl Baedeker |language=de}}</ref> produced in what is today [[Gdańsk]], [[Poland]], and [[Schwabach]], Germany, and contains flakes of gold leaf. There are also some expensive (c. $1000) cocktails which contain flakes of gold leaf. However, since metallic gold is inert to all body chemistry, it has no taste, it provides no nutrition, and it leaves the body unaltered.<ref>{{cite web |url=http://geology.com/minerals/gold/uses-of-gold.shtml |title=The Many Uses of Gold |access-date=6 June 2009 |author=King, Hobart M. |publisher=geology.com}}</ref> * [[Vark]] is a [[Metal leaf|foil]] composed of a pure metal that is sometimes gold,<ref>[http://www.delafee.com/Edible+Gold+Creations_Information+on+edible+gold/ Gold in Gastronomy] {{Webarchive|url=https://web.archive.org/web/20160304002554/http://www.delafee.com/Edible+Gold+Creations_Information+on+edible+gold/ |date=4 March 2016 }}. deLafee, Switzerland (2008)</ref> and is used for [[Garnish (food)|garnishing]] sweets in South Asian cuisine. === Miscellanea === [[File:James Webb Space Telescope Mirror33.jpg|thumb|Mirror for the [[James Webb Space Telescope]] coated in gold to reflect infrared light]] [[File:Kamakshi Amman Temple with golden roof, Kanchipuram.jpg|thumb|Kamakshi Amman Temple with golden roof, [[Kanchipuram]].]] * Gold produces a deep, intense red color when used as a coloring agent in [[cranberry glass]]. * In photography, gold toners are used to shift the color of [[silver bromide]] black-and-white prints towards brown or blue tones, or to increase their stability. Used on [[sepia tone|sepia-toned]] prints, gold toners produce red tones. Kodak published formulas for several types of gold toners, which use gold as the chloride.<ref>[https://web.archive.org/web/20160817134815/http://www.kodak.com/global/en/professional/support/techPubs/g23/g23.pdf Toning black-and-white materials]. Kodak Technical Data/Reference sheet G-23, May 2006.</ref> * Gold is a good reflector of [[electromagnetic radiation]] such as [[infrared]] and [[visible spectrum|visible light]], as well as [[radio frequency|radio waves]]. It is used for the protective coatings on many artificial [[satellite]]s, in infrared protective faceplates in thermal-protection suits and astronauts' helmets, and in [[electronic warfare]] planes such as the [[EA-6B Prowler]]. * Gold is used as the reflective layer on some [[Gold CD|high-end CDs]]. * Automobiles may use gold for heat shielding. [[McLaren]] uses gold foil in the engine compartment of its [[McLaren F1|F1]] model.<ref>{{cite book |last1=Martin |first1=Keith |url=https://books.google.com/books?id=pUhMRLiHiY8C&pg=PA42 |title=1997 McLaren F1}}</ref> * Gold can be manufactured so thin that it appears semi-transparent. It is used in some aircraft cockpit windows for [[Deicing|de-icing]] or anti-icing by passing electricity through it. The heat produced by the resistance of the gold is enough to prevent ice from forming.<ref name="gbc215">{{Cite news |url=http://www.goldbulletin.org/assets/file/goldbulletin/downloads/Cooke_2_15.pdf |archive-url=https://web.archive.org/web/20110726122946/http://www.goldbulletin.org/assets/file/goldbulletin/downloads/Cooke_2_15.pdf |archive-date=26 July 2011 |title=The Demand for Gold by Industry |publisher=Gold bulletin |access-date=6 June 2009}}</ref> * Gold is attacked by and dissolves in alkaline solutions of potassium or sodium [[cyanide]], to form the salt gold cyanide—a technique that has been used in extracting metallic gold from ores in the [[cyanide process]]. Gold cyanide is the [[electrolyte]] used in commercial [[electroplating]] of gold onto base metals and [[electroforming]]. * Gold chloride ([[chloroauric acid]]) solutions are used to make colloidal gold by reduction with [[citrate]] or [[ascorbate]] [[ions]]. Gold chloride and gold oxide are used to make cranberry or red-colored glass, which, like [[colloid]]al gold suspensions, contains evenly sized spherical [[gold nanoparticle]]s.<ref>{{cite web |url=http://chemistry.about.com/cs/inorganic/a/aa032503a.htm |title=Colored glass chemistry |access-date=6 June 2009 |archive-date=13 February 2009 |archive-url=https://web.archive.org/web/20090213164051/http://chemistry.about.com/cs/inorganic/a/aa032503a.htm |url-status=dead }}</ref> * Gold, when dispersed in nanoparticles, can act as a [[Heterogeneous gold catalysis|heterogeneous catalyst]] of chemical reactions. * In recent years, gold has been used as a symbol of pride by the [[autism rights movement]], as its symbol Au could be seen as similar to the word "[[Autism spectrum disorder|autism]]".<ref>{{cite web |date=2 April 2021 |title=Why 'Going Gold' is important on Autism Acceptance Day. |url=https://edpsy.org.uk/blog/2021/why-going-gold-is-important-on-autism-acceptance-day-2nd-april/ |website=Edpsy}}</ref> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. 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