Why are higher gold and diamond minerals found in south Africa? What makes this area so prevalent for these minerals ?
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Why are higher gold and diamond minerals found in south Africa? What makes this area so prevalent for these minerals ?
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I believe both of these are formed by hydrothermal processes and I suspect South Africa has the right gelogy for these.
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The diamond is found in kimberlite. Ancient deep volcanics if I remember right. Oddly enough, Arkansas in the US has a fairly productive area. Not much in gemstones, but a bit of grit.
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Nano diamonds have been found in meteorites, and I still subscribe to the conjecture that someday we will come across a meteorite with larger diamonds and I hold out the possibility that some diamonds found on Earth are supernova products.Originally Posted by korjik
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Arkansas may not be much for gemstone grade diamonds, but it is very good for gemstone grade quartz, which is also hydrothermally formed.
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Quartz---isn't that a gold indicator?
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Gold is found with quartz, but finding quartz does not indicate gold. Finding a hydrothermal vein of quartz in basalt might warrant further investigation, however.
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JL. Very good....which is why if you are hiking with friends in a relatively unexplored area....and you find black sand mixed with white sand...basalt & quartz respectively, in a streambed....you at least ought to check out any nearby veins of quartz that are exposed. Cohasset beach South of Boston,MA is black basaltic sand(neck of an old volcano)...and both nearby Weymouth, MA, and Boxford showed as part of the Boston basin...silver & gold mines. psssst...there's still a little bit there. pete
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I'm pretty sure that diamonds are not formed in hydrothermal processes. At least, none we know about
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Why are there gold and diamonds in South Africa? Mainly because South Africa is big. 1.21 million square kilometers. Look at any chunk of land that big and you are almost certain to find valuable mineral deposits, which in South Africa's case include gold and diamonds. Add to that the fact that no one felt much need to respect the property rights of the people living on the mine sites and the ability to use those people as a cheap labour source, combined with European technical expertise, and you have a recipie for a low cost producer.
An interesting aside, an asteroid smacking into South Africa long ago aparently created conditions right for gold deposits to form. (Note the gold wasn't in the asteroid.)
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Maybe, but I'm not sure that's a useful answer. Obviously, in general, a larger country has more resources than a smaller one.
The presence or absence of minerals is solely dependent on geology. As mentioned, SA has kimberlite pipes. Gold is commonly found in areas with large igneous instrusive bodies. SA has those.
Rather than size, age might be a better indicator. SA contains, or partly comprises, some very old rock. What that means is that many, many varied geologic processes have occurred in that region over the billions of years, as opposed to a younger terrane. Higher probability that processes that tend to concentrate gold will have taken place.
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The reason diamonds are so rare is that they are kept artifically scarce. The De Beers company, which is a cartel of families that own mines in South Africa (most of the families are British and De Beers was the original names of the owner of the farm the first diamond mine was found). They only sell the expected amount of marriages in the United States. So the price is always high. They also have a marketing campaign in the US (A diamond is forever) to get people interested in diamonds.
Banned
Should this go into the Conspiracy Theory Section?
If their campaign is "Diamonds Are Forever" to keep prices high- it seems a bit backwards.
If they want demand and market, they should say, "Diamonds are maybe 6 months. Then you better buy her a new one and keep her happy so she doesn't leave you."
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My point/question was, why is South Africa's geology so synonymous for Gold and Diamonds, why not any where else. Assuming that the continents were all one many millions of years ago.......
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I think I provided a reasonable answer to that question. Note that just because supercontinents formed, that doesn't mean everything was homogenized. The distinct continental masses retained much of their historical geologic character.
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My understanding is that the kimberlite pipes are the remains of quite deep mantle plumes now solidified and the erosion of Africa has exposed them enough to bring them close to the surface, Diamonds are formed at high pressure and temperature so not easily brought to the surface.
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This article has a quick guide to formation, http://scienceweek.com/2003/sc031010-5.htm (13kb)
gold melts at low temps and gets carried to the surface in hydrothermal vents around the edges of granitic batholiths (as is quartz) and they solidify out into veins in the country rock as the pressure reduces, this is closer to the surface than diamonds hence more common. As erosion occurs gold, being heavy and non-reactive, gets left behind as alluvial deposits,
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The purpose of the campaign is not to keep prices high. It is to keep demand high enough! De Beers has a defacto monopoly on diamonds. Should any "competitor" try to undercut De Beers, all De Beers would have to do is flood the market, driving the others out of business.
The "Diamonds Are Forever" campaign has been unbelievably successful at equating diamonds with engagement rings! Imagine the [trouble] a guy would be in if he cheaped out and bought his girlfriend a topaz engagement ring.That would be the shortest engagement in history! All because of De Beers and "Diamonds Are Forever"!
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I'd use a cigar ring. And if she's that materialistic- no small loss on my part.The "Diamonds Are Forever" campaign has been unbelievably successful at equating diamonds with engagement rings! Imagine the [trouble] a guy would be in if he cheaped out and bought his girlfriend a topaz engagement ring.
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Agreed!but that definitely puts us in a distinct minority.
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I assume you and Neverfly are single?Agreed!
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Currently? Yes!I assume you and Neverfly are single?
Been married twice!
First wife thought I was crazy.
Second time, I wasn't crazy enough! She left me for a drunk whose favorite "sport" was dumpster diving!
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Hey Sean,
and of course everybody wants to look at where South Africa once attached to Antartica to see if there is a similar geology. For science reasons don't you know.
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I'm unmarried, But I'm taken and no longer on the marketI assume you and Neverfly are single?
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Gold and diamonds in Antarctica,,,sshhhhhhhhh, dont tell anybody.
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Tell them that you are looking for dinosaurs and need to understand the geology to identify the Mesozoic formations.
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Thought drilling ice cores would be better excuse......
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Needs to be done, and specifically, are there magnetic grains at the 12.9kya section of ice.
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Could a major impact create diamonds, or is it more to gradual increased pressure ?
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I do not think so because the carbon would be volatilized. As a possible example, I do not recall any indication of diamonds in Lunar regolith, which should be a good sampling of prolonged and overlapping impact events.
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