question: Why does gold run in veins? All heavy metals like this come from supernovas. Why would they concentrate in some position when they eventually make it to Earth?
comment: It's not like gold is formed in a supernova or some other celestial process and then slowly makes its way to an already existing Earth. What happens is that billions and billions and billions of years ago, certain elements were formed in supernova and widely dispersed. These elements ended up intermixed in giant clouds of mostly hydrogen gas, which coalesced into a rotating disk of matter, which further coalesced into our sun at its center and lots of dust and small rocky objects orbiting what would become the sun. Over millennia, the smaller rocky objects, some of which contained gold, coalesced into larger and larger objects. The heat of the collisions of these bodies melted them, and heavier elements tended to clumped together, and some of it sunk toward the interior of the molten ball of Rock. Plate tectonics, subduction, and volcanism, provided ongoing mixing and melting of these materials. Gold tended to clump together since it was denser than most of the surrounding materials, and as it cooled, it did so in clumps, or veins. In mountain forming regions, these veins and the surrounding rock was pushed up into the spots we find it today. This is an ongoing process, but it happens on geological time scales. /edited for typos
passages: Ores related to hydrothermal mineralisation, which are associated with vein material, may be composed of vein material and/or the rock in which the vein is hosted.
  
  Section::::Mineralization and veining.:Gold-bearing veins.
  
  In many gold mines exploited during the gold rushes of the 19th century, vein material alone was typically sought as ore material. In most of today's mines, ore material is primarily composed of the veins and some component of the wall rocks which surrounds the veins.
   However, today's mining and assaying allows the delineation of lower-grade bulk tonnage mineralisation, within which the gold is invisible to the naked eye. In these cases, veining is the subordinate host to mineralisation and may only be an indicator of the presence of metasomatism of the wall-rocks which contains the low-grade mineralisation. 
  
  For this reason, veins within hydrothermal gold deposits are no longer the exclusive target of mining, and in some cases gold mineralisation is restricted entirely to the altered wall rocks within which entirely barren quartz veins are hosted.
  
  Section::::See also.
  
  BULLET::::- Boudinage
  
  BULLET::::- Ore genesis
   Metal sources may include a plethora of rocks. However most metals of economic importance are carried as trace elements within rock-forming minerals, and so may be liberated by hydrothermal processes. This happens because of:
  
  BULLET::::- incompatibility of the metal with its host mineral, for example zinc in calcite, which favours aqueous fluids in contact with the host mineral during diagenesis.
  
  BULLET::::- solubility of the host mineral within nascent hydrothermal solutions in the source rocks, for example mineral salts (halite), carbonates (cerussite), phosphates (monazite and thorianite), and sulfates (barite)
  
  BULLET::::- elevated temperatures causing decomposition reactions of minerals
   Eluvial ore deposits are those such as tungsten and gold placer deposits formed by settling and enriched by the winnowing or removal of lower density materials. Diamonds within "yellow ground" (weathered portions of kimberlites) may be considered to be eluvial deposits. Cassiterite and columbite-tantalite deposits also occur as residual or eluvial concentrations. The Pitinga tin deposit in Brazil, an eluvial deposit, is one of the largest tin mines in the world. Weathering "supergene" enrichment of an apatite rich carbonatite in Ontario has produced a significant eluvial phosphate ore deposit.
  
  Section::::See also.
  
  BULLET::::- Alluvium
  
  BULLET::::- Colluvium
  
  BULLET::::- Diluvium
  
  BULLET::::- Lessivage
  
  Section::::References.
   Section::::Occurrence.
  
  On Earth, gold is found in ores in rock formed from the Precambrian time onward. 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 8–10%. Electrum is elemental gold with more than 20% silver. Electrum's color runs from golden-silvery to silvery, dependent upon the silver content. The more silver, the lower the specific gravity.
   Gravity concentration has been historically the most important way of extracting the native metal using pans or washing tables. Amalgamation with mercury was used to enhance recovery, often by adding it directly to the riffle tables, and mercury is still widely used in small diggings across the world. However, froth flotation processes may also be used to concentrate the gold. In some cases, particularly when the gold is present in the ore as discrete coarse particles, a gravity concentrate can be directly smelted to form gold bars. In other cases, particularly when the gold is present in the ore as fine particles or is not sufficiently liberated from the host rock, the concentrates are treated with cyanide salts, a process known as cyanidation leaching, followed by recovery from the leach solution. Recovery from solution typically involves adsorption on activated carbon then stripping (eluting) the gold from the carbon and passing the pregnant solution through electrowinning and then onto the smelting process.
   Supergene profiles can be developed above weathered examples of IOCG deposits, as exemplified by the Sossego deposit, Para State, Brazil, where typical oxidised copper minerals are present, e.g.; malachite, cuprite, native copper and minor amounts of digenite and chalcocite.
   The grade of a typical heavy mineral sand ore deposit is usually low. Within the 21st century, the lowest cut-off grades of heavy minerals, as a total heavy mineral (THM) concentrate from the bulk sand, in most ore deposits of this type is around 1% heavy minerals, although several are higher grade.
  
  Of this total heavy mineral concentrate (THM), the components are typically 
  
  BULLET::::- Zircon, from 1% of THM to upwards of 50% of THM,
  
  BULLET::::- Ilmenite, generally of 10% to 60% of THM
  
  BULLET::::- Rutile, from 5% to 25% of THM
   The difference between 19th-century and 21st-century mining techniques and the type of ore sought is based on the grade of material being mined and the methods of mining which are used. Historically, hand-mining of gold ores permitted the miners to pick out the lode quartz or reef quartz, allowing the highest-grade portions of the lodes to be worked, without dilution from the unmineralised wall rocks.
  
  Today's mining, which uses larger machinery and equipment, forces the miners to take low-grade waste rock in with the ore material, resulting in dilution of the grade.
   Gold, a siderophile, is most commonly recovered by dissolving the ores in which it is found in a cyanide solution. The gold forms a dicyanoaurate(I), for example: 2 Au + HO +½ O + 4 KCN → 2 K[Au(CN)] + 2 KOH. Zinc is added to the mix and, being more reactive than gold, displaces the gold: 2[Au(CN)] + Zn → K[Zn(CN)] + 2 Au. The gold precipitates out of solution as a sludge, and is filtered off and melted.
  
  Section::::Properties compared with light metals.
   BULLET::::- Interspinifex ore, developed on the upper contact of the basal flow and on the basal contact of a fertile second flow. In some cases, liquid sulfide from the second flow is seen intermingled intimately with spinifex-textured ultramafic flow tops of the basal flow (e.g.; Long-Victor Shoot, Kambalda) and may be present above remnant sediments and intermingled with remnant sediments (e.g.; Hilditch Prospect, Wannaway, Bradley Prospect, Location 1 and likely others).
   BULLET::::- Fractional crystallization: separates ore and non-ore minerals according to their crystallization temperature. As early crystallizing minerals form from magma, they incorporate certain elements, some of which are metals. These crystals may settle onto the bottom of the intrusion, concentrating ore minerals there. Chromite and magnetite are ore minerals that form in this way.
   Mining may not be necessary, if the ore body and physical environment are conducive to leaching. Leaching dissolves minerals in an ore body and results in an enriched solution. The solution is collected and processed to extract valuable metals.
  
  Ore bodies often contain more than one valuable metal. Tailings of a previous process may be used as a feed in another process to extract a secondary product from the original ore. Additionally, a concentrate may contain more than one valuable metal. That concentrate would then be processed to separate the valuable metals into individual constituents.
  
  Section::::Alloys.
   This process, which occurs primarily when fluids are driven off the cooling magma, is one of the main reasons for the existence in the world of rich, localized metal ore deposits such as those of gold, copper, molybdenum, lead, tin, zinc, rhenium and tungsten. This enrichment occurs in the porphyry itself, or in other related igneous rocks or surrounding country rocks, especially carbonate rock (in a process similar to skarns). Collectively, these type of deposits are known as "porphyry copper deposits".
  
  Section::::Formation.:Rhomb porphyry.
   Once the ore is mined it can be treated as a whole ore using a dump leaching or heap leaching processes. This is typical of low-grade, oxide deposits. Normally, the ore is crushed and agglomerated prior to heap leaching. High grade ores and ores resistant to cyanide leaching at coarse particle sizes, require further processing in order to recover the gold values. The processing techniques can include grinding, concentration, roasting, and pressure oxidation prior to cyanidation.
  
  Section::::History.
   BULLET::::- The "source" of ore within manto deposits is considered to be interformational, from a sedimentary source within an adjacent sedimentary basin, or from ore fluids driven off from a granite intrusive.
  
  BULLET::::- The "transport" of copper into the manto deposit position was likely hydrothermal, either a metamorphic solution or copper-bearing hydrothermal solutions generated by intrusive granites.
   Another scenario involves the formation or breakdown of garnet, influencing the Y and HREE (heavy rare earth elements) content in the environment, thus the content of growing monazite. Basically, monazite growth before garnet formation has a higher Y and HREE content than those during or after garnet formation. As garnet start breaking down in the later stage of metamorphism, the monazite forms rims rich in Y and HREE.
   Gold occurs principally as a native metal, usually alloyed to a greater or lesser extent with silver (as electrum), or sometimes with mercury (as an amalgam). Native gold can occur as sizeable nuggets, as fine grains or flakes in alluvial deposits, or as grains or microscopic particles (known as color) embedded in rock minerals.
  
  Ores in which gold occurs in chemical composition with other elements are comparatively rare. They include calaverite, sylvanite, nagyagite, petzite and krennerite.
  
  Section::::Concentration.
   Plate tectonics is the underlying mechanism for generating gold deposits. The majority of primary gold deposits fall into two main categories: lode gold deposits or intrusion-related deposits.
  
  "Lode gold deposits" are generally high-grade, thin, vein and fault hosted. They are primarily made up of quartz veins also known as lodes or "reefs", which contain either native gold or gold sulfides and tellurides. Lode gold deposits are usually hosted in basalt or in sediments known as turbidite, although when in faults, they may occupy intrusive igneous rocks such as granite.
   Section::::Ore deposits.:Classification.
  
  Ore deposits are classified according to various criteria developed via the study of economic geology, or ore genesis. The classifications below are typical.
  
  Section::::Ore deposits.:Classification.:Hydrothermal epigenetic deposits.
  
  BULLET::::- "Mesothermal" lode gold deposits, typified by the Golden Mile, Kalgoorlie
  
  BULLET::::- Archaean conglomerate hosted gold-uranium deposits, typified by Elliot Lake, Ontario, Canada and Witwatersrand, South Africa
  
  BULLET::::- Carlin–type gold deposits, including;
  
  BULLET::::- "Epithermal" stockwork vein deposits
  
  Section::::Ore deposits.:Classification.:Granite related hydrothermal.
  
  BULLET::::- IOCG or iron oxide copper gold deposits, typified by the supergiant Olympic Dam Cu-Au-U deposit
  
  BULLET::::- Porphyry copper +/- gold +/- molybdenum +/- silver deposits
   BULLET::::- The "source" of metal and sulfur in VMS deposits is a combination of incompatible elements which are leached from the volcanic pile in the sub-seafloor hydrothermal alteration zone by hydrothermal circulation. Hydrothermal circulation is generally considered to be driven via heat in the crust often related to deep-seated gabbro intrusions.
   BULLET::::- Fractures are often filled or coated by sulfides, or by quartz veins with sulfides. Closely spaced fractures of several orientations are usually associated with the highest grade ore.
  
  BULLET::::- The upper portions of porphyry copper deposits may be subjected to supergene enrichment. This involves the metals in the upper portion being dissolved and carried down to below the water table, where they precipitate.
  
  Porphyry copper deposits are typically mined by open-pit methods.
  
  Section::::Examples of porphyry copper deposits.
  
  Section::::Examples of porphyry copper deposits.:Mexico.
  
  BULLET::::- Santo Tomas
  
  Section::::Examples of porphyry copper deposits.:Chile.
  
  BULLET::::- Cerro Colorado
  
  BULLET::::- Chuquicamata
  
  BULLET::::- Collahuasi
  
  BULLET::::- Escondida
   BULLET::::- Mexico: In blue-green gem quality crystals to 8 cm at the San Antonio Mine, Santa Eulalia, Chihuahua.
  
  BULLET::::- Russia: In sedimentary iron ores and in fossil shells in the Kerch and Taman peninsula on the Black Sea.
  
  BULLET::::- Spain: At the Brunita mine, Cartagena, Murcia, vivianite was found as deep green crystals, up to 8 cm
  
  BULLET::::- USA: In diatomite in a tertiary lake bed near Burey, Shasta County, California.
  
  BULLET::::- USA: In green sand at Middletown, New Castle County, Delaware.
   BULLET::::- Epithermal mineral ore deposits are formed at low temperatures (50-200 °C) near the Earth's surface (1500 m), that fill veins, breccias, and stockworks.
  
  BULLET::::- Telethermal mineral ore deposit are formed at shallow depth and relatively low temperatures, with little or no wall-rock alteration, presumably far from the source of hydrothermal solutions.
   Important sources of sulfur in ore deposits are generally deep-seated, but they can also come from local country rocks, sea water, or marine evaporites. The presence or absence of sulfur is one of the limiting factors on both the concentration of precious metals and its precipitation from solution. pH, temperature and especially redox states determine whether sulfides will precipitate. Most sulfide brines will remain in concentration until they reach reducing conditions, a higher pH or lower temperatures. 
  
presuppositions: Because gold is a metal it should come from supernovas like most other metals and not veins. 
corrections: Technically gold did come from supernovas because the rocks that came from supernovas because some of the rocks contained gold. 
raw_presuppositions: Because gold is a metal it should come from supernovas like most other metals and not veins.  Elements derived from supernovas arrived at an already-formed Earth.
raw_corrections: Technically gold did come from supernovas because the rocks that came from supernovas because some of the rocks contained gold.  Elements derived from supernovas arrived in the solar system before the Earth was formed.