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! == Occurrence == [[File:Gold nugget (Australia) 4 (16848647509).jpg|thumb|left|upright=0.7|[[Native metal|Native gold]].]] On Earth, gold is found in [[ore]]s in rock formed from the [[Precambrian]] time onward.<ref name="La Niece" /> It most often occurs as a [[native metal]], typically in a metal [[solid solution]] with silver (i.e. as a gold/silver [[alloy]]). Such alloys usually have a silver content of 8β10%. [[Electrum]] is elemental gold with more than 20% silver, and is commonly known as [[white gold]]. Electrum's color runs from golden-silvery to silvery, dependent upon the silver content. The more silver, the lower the [[specific gravity]]. Native gold occurs as very small to microscopic particles embedded in rock, often together with [[quartz]] or [[sulfide mineral]]s such as "[[fool's gold]]", which is a [[pyrite]].<ref>{{cite web |url=http://arizonagoldprospectors.com/formation.htm |title=Formation of Lode Gold Deposits |author=Heike, Brian |url-status=dead |archive-url=https://web.archive.org/web/20130122100747/http://arizonagoldprospectors.com/formation.htm |archive-date=22 January 2013 |publisher=Arizona Gold Prospectors|access-date=24 February 2021}}</ref> These are called [[lode]] deposits. The metal in a native state is also found in the form of free flakes, grains or larger [[Gold nugget|nuggets]]<ref name="La Niece" /> that have been eroded from rocks and end up in [[alluvial]] deposits called [[placer deposit]]s. Such free gold is always richer at the exposed surface of gold-bearing veins, owing to the [[oxidation]] of accompanying minerals followed by weathering; and by washing of the dust into streams and rivers, where it collects and can be welded by water action to form nuggets. Gold sometimes occurs combined with [[tellurium]] as the [[mineral]]s [[calaverite]], [[krennerite]], [[nagyagite]], [[petzite]] and [[sylvanite]] (see [[telluride mineral]]s), and as the rare bismuthide maldonite ({{chem2|Au2Bi}}) and antimonide [[aurostibite]] ({{chem2|AuSb2}}). Gold also occurs in rare alloys with [[copper]], [[lead]], and [[mercury (element)|mercury]]: the minerals [[auricupride]] ({{chem2|Cu3Au}}), novodneprite ({{chem2|AuPb3}}) and weishanite ({{chem2|(Au,Ag)3Hg2}}). A 2004 research paper suggests that microbes can sometimes play an important role in forming gold deposits, transporting and precipitating gold to form grains and nuggets that collect in alluvial deposits.<ref>{{cite web |url=http://www.abc.net.au/science/news/enviro/EnviroRepublish_1032376.htm |title=Environment & Nature News β Bugs grow gold that looks like coral |date=28 January 2004 |access-date=22 July 2006 |publisher=abc.net.au}} This is doctoral research undertaken by Frank Reith at the Australian National University, published 2004.</ref> A 2013 study has claimed water in faults vaporizes during an earthquake, depositing gold. When an earthquake strikes, it moves along a [[fault (geology)|fault]]. Water often lubricates faults, filling in fractures and jogs. About {{convert|10|km}} below the surface, under very high temperatures and pressures, the water carries high concentrations of carbon dioxide, silica, and gold. During an earthquake, the fault jog suddenly opens wider. The water inside the void instantly vaporizes, flashing to steam and forcing silica, which forms the mineral quartz, and gold out of the fluids and onto nearby surfaces.<ref>{{cite web |url=https://news.yahoo.com/earthquakes-turn-water-gold-180356174.html |title=Earthquakes Turn Water into Gold |date=17 March 2013 |access-date=18 March 2013}}</ref> === Seawater === The world's [[ocean]]s contain gold. Measured concentrations of gold in the Atlantic and Northeast Pacific are 50β150 [[femtomolar|femtomol]]/L or 10β30 parts per [[quadrillion]] (about 10β30 g/km<sup>3</sup>). In general, gold concentrations for south Atlantic and central Pacific samples are the same (~50 femtomol/L) but less certain. Mediterranean deep waters contain slightly higher concentrations of gold (100β150 femtomol/L) attributed to wind-blown dust or rivers. At 10 parts per quadrillion the Earth's [[oceans]] would hold 15,000 tonnes of gold.<ref>{{Cite journal |doi=10.1016/0012-821X(90)90060-B |title=Gold in seawater |first1=K. |last1=Kenison Falkner |author-link1=Kelly Falkner|journal=Earth and Planetary Science Letters |volume=98 |date=1990 |pages=208β221 |last2=Edmond |first2=J. |issue=2 |bibcode=1990E&PSL..98..208K}}</ref> These figures are three orders of magnitude less than reported in the literature prior to 1988, indicating contamination problems with the earlier data. A number of people have claimed to be able to economically recover gold from [[sea water]], but they were either mistaken or acted in an intentional deception. [[Prescott Jernegan]] ran a gold-from-seawater swindle in the [[United States]] in the 1890s, as did an English fraudster in the early 1900s.<ref>Plazak, Dan ''A Hole in the Ground with a Liar at the Top'' (Salt Lake: Univ. of Utah Press, 2006) {{ISBN|0-87480-840-5}} (contains a chapter on gold-from seawater swindles)</ref> [[Fritz Haber]] did research on the extraction of gold from sea water in an effort to help pay [[Germany]]'s reparations following [[World War I]].<ref>{{Cite journal |title=Das Gold im Meerwasser |first=F. |last=Haber |volume=40 |issue=11 |date=1927 |doi=10.1002/ange.19270401103 |pages=303β314 |journal=Zeitschrift fΓΌr Angewandte Chemie|bibcode=1927AngCh..40..303H }}</ref> Based on the published values of 2 to 64 ppb of gold in seawater, a commercially successful extraction seemed possible. After analysis of 4,000 water samples yielding an average of 0.004 ppb, it became clear that extraction would not be possible and he ended the project.<ref>{{Cite journal |doi=10.1016/0375-6742(88)90051-9 |title=Concentration of gold in natural waters |first=J. B. |last=McHugh |journal=Journal of Geochemical Exploration |volume=30 |date=1988 |pages=85β94 |issue=1β3 |bibcode=1988JCExp..30...85M |url=https://zenodo.org/record/1258491 |archive-url=https://web.archive.org/web/20200307233511/https://zenodo.org/record/1258491 |url-status=dead |archive-date=7 March 2020}}</ref><!--10.1007/BF01497020--> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Christianpedia:Copyrights for details). 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