Becca Hedges
Geo 3210-01
Dr. MacLean
20 Jan. 2017
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Reflection 3
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Gold, the metallic yellow mineral is desired for its malleability and beauty. Personally, it is my very least favorite mineral. Gold is the oldest mined substance on Earth and it has numerous uses in many different industries. Gold isn’t truly formed or produced, at least not on this planet. According to the National Geographic documentary “How the Earth was made” gold is actually created in outer space. Over 5 billion years ago inside massive stars is where it begins. As stars die they explode becoming a supernova. Immediately after this explosion, the metal began to travel to the area where the Earth was beginning to form. The particles of gold are tiny and moved about 70 million miles per hour thru space. Therefore the purest form of gold is actually an element, notated by the symbol Au on the periodic table of elements. During the formation of our planet, iron sank due to its high density and formed the planet’s core. This iron took other heavy elements, like gold, with it trapping the tiny particles inside other material. The core of the Earth is where most of the gold on the planet should be, rather than in the crust where we find it.
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Because the gold is so near the earth’s surface, humans have been able to stumble across it above ground and extract it through mining. USGS Geologist Richard Goldfarb estimates that 160 thousand tons of gold have been found in very particular places worldwide. While some locations like China and South Africa have highly concentrated deposits, gold is everywhere. Veins of gold are formed a few different ways. Plate tectonics are undoubtedly a large part in this process.
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During the mid-1800’s gold was discovered in California. The men who traveled there to stake their claim were called the 49ers. They noticed in the riverbeds with heavy black sand along banks housed deposits. A little while later underneath rounded boulders in the valley walls they discovered more deposits. It was determined that these were ancient river beds. However, the question remains, where is the main source of all this gold? Prospectors were paying attention to geologic formations and making connections. They began searching for large quartz veins. The veins also happened to run near parallel to the coast. What was determined from this was that the quartz bearing gold at one point was a super-heated fluid saturated with dissolved minerals and was deposited in cracks and faults created by the nearby subducting plate. The subducting plate caused the ocean floor to be pushed up and folded. The intense pressure and heat allowed for the superheated fluid to flow into the voids created by this deformation. As the fluid cooled the quartz crystalized with the gold trapped inside. There are similar deposits like this found all along the pacific ring of fire. At first it was though that this was the only know way these deposits were formed.
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In a location that has long been on my bucket list of places to visit is Bodie Ca. This location boarders Nevada and is thought to have a curse placed on it. A man named Bodie is said to haunt the area because he was left to die in a sudden winter storm by his business partner after finding a rich gold deposit. His business partner then claimed the deposit for himself which brought other prospectors to the area as well. It has always been one of the harder places to live in the west. They say that if anyone who visits the area takes anything they will have nothing but bad luck. The type of gold deposits likely found by Bodie are different from the deposits created by orogenies.
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These deposits were randomly scattered all over the desert. While still involving quartz and gold veins these deposits are also littered with silver. This area does not exhibit crushed or altered features. These were created by volcanic activity. Deep underground laminated quarts and silver veins are speckled with gold. On the surface are various colors of laminations. The volcanic activity caused the groundwater and/or water that has seeped down from the surface to become heated. As discussed with the California deposits this super-heated fluid has dissolved minerals in it. Once heated it finds its way to the surface through any weaknesses in the sediment it can find creating hot springs. As it cools the minerals are deposited out of the fluid. These deposits are hard to extract minerals which proved to be unprofitable during this time.
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A Geologist named John Livermore in 1961 had a theory that gold deposits would be near cracks in the ground. He found one in Nevada 50 miles long. When he went to that location he found deposits of a mud and quartz mixture but, there was no visible gold. He took some samples to a lab for testing and this location is now one of the largest gold mines in the world. 10 tons of rock are taken to gain one ounce of gold. These deposits are also determined to be produced by hydrothermal fluids. A few years later the discovery of Lehman’s cave unveiled new information regarding the formation of the deposits Livermore discovered. Geologists believe these two locations were once the same deposits but the gold bearing ore Livermore discovered must have has some kind of attack from an acidic solution creating a spongy sediment altering the limestone. Similar deposits of this type are still being found around the world
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The topic question of how is gold produced is somewhat misleading. Gold is really not produced but created. In the sense of production, that comes from the physical act of taking the mineral from the ground, mining. From there it is melted, formed, and re-melted again to produce a product consumer’s want. Throughout human history gold has been desired. Tons of gold has been extracted from all over the world. No one know how much gold may be on earth. Some say there is no reason to doubt we haven’t even extracted half the total amount on Earth. Gold may have begun in space but, so long as humans live we will be searching for more gold on Earth.