Shall we discover how to make gold, titanium,…. from less valuable metals? Shall we experiment on Earth, Moon, Mars, Saturn, space ships? Where shall we have success and when? What costs?

24 Jun

I am the first to think about it, I see no articles on the Internet, so I deserve some credit and share of the profits! Let’s do it and we’ll have hopefully cheap, rust free products and tools soon. We can experiment with temperature, pressure, laser, waves, germs, and what else?

 

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Bacteria Make Gold

The largest single lump of gold ever discovered on our planet was found in Australia. It was the Holterman Nugget, and it was found in Hill End in NSW on 19 October, 1872. The whole nugget weighed 235.1 kg, and contained 93.3 kg of pure gold. (Strictly speaking, the Holterman Nugget was not really a nugget, but a mass of gold found in a reef.)

Many of the world’s large gold nuggets have come out of Australia – the Hand of Faith (27.2 kg), the Welcome Stranger (73.4 kg), and the Welcome (69. 9 kg). Ever since I was a kid, one thing about nuggets has always struck me as odd – they look so ‘organic’, like a lumpy mis-shapen potato. Well, my gut feeling might have been right. According to some recent research, gold nuggets might have been assembled by living creatures!

Gold is usually found either as a free metal in the gravel of streams and rivers, or else intermingled with quartz in veins in the rock. In 1988, South Africa mined 621 tonnes of gold, the USA mined 205 tonnes, with Australia at third place with 152 tonnes – a total of 978 tonnes of gold. This gold would fit into a box 3.7 metres on each side. (The richest goldfield in the world is the Witwatersrand in South Africa – the rand, South Africa’s currency is named after this goldfield).

There is some gold in the oceans, but it would be hard to get rich by processing it. There are only ten grams of gold in each cubic kilometre of the Pacific and Atlantic Oceans. However, the Mediterranean Sea is three times more concentrated in gold (probably because it is landlocked, and the gold washed in from the rivers takes longer to get diluted).

Gold is very inert, and very resistant to attack by chemicals. If you bury some in your backyard, it will look the same in thousands of years. It is used in jewellery, because it does not tarnish, because it is soft and easy to work and because it is very rare.

About 65% of gold is used in the jewellery trade. The electrical, electronic and other industrial fields use 25% of the gold mined. Gold is an excellent conductor of heat and electricity, and does not tarnish or oxidise. Gold can be beaten into a transparent gold foil (0.00013 mm thick) over 500 times thinner than a human hair. Dentistry uses about 7% of the gold produced. Here it is alloyed with other metals (such as copper, silver, platinum and palladium) for restorations, partial dentures, bridges and inlays.

Now some scientists believe that bacteria might have actually laid down some of the gold deposits in the first place. After all, when a bacteria called Pedomicrobiumlives in water rich in dissolved minerals, it will actually build up layers of iron or manganese oxide around itself – like a shell. Scientists from Macquarie University have suggested that many gold deposits in Venezuala might have been laid down by bacteria. And just recently, John R. Watterson of the US Geological Survey, claims to have found proof in Alaska.

Now when most people find a lump of gold in their gold-panning dish, they quickly turn it into cold hard cash – and have a party. But when John R. Watterson got his gold, he looked at it with a scanning electron microscope. To his surprise, most of the tiny particles of gold that he had collected from nine Alaskan rivers were not solid little lumps. Instead, they looked like gold-plated bacteria.

What he saw was a lacy pattern of tiny cylinders joined by thin rods. The cylinders were the same size as the Pedomicrobium bacteria.

Now gold stops most bacteria dead in their tracks – with suffocation. It blocks up the tiny holes in the cell walls through which food comes in and wastes go out. But Pedomicrobium, has an unusual way of reproduction. Most bacteria make babies just by splitting into two separate cells. But Pedomicrobium reproduces by budding. It stretches out a narrow stalk which rises above the gilded cage closing around the parent bacteria. This narrow tube then opens up (at the end) to make a new bacteria. So new baby bacteria are continually being born just on the outside of an expanding ball of golden death. It’s a slow process – it takes over a year to ‘grow’ a gold grain roughly the thickness of a human hair (about 0.1 mm). It would take a long time to ‘grow’ a 70 kg nugget. (Maybe we could speed the process up, by genetically engineering thePedomicrobium bacteria.)

There are similar lacy patterns in 2.8 billion-year-old South African gold, and in 220 million-year-old Chinese gold. Of course, when you melt the gold in a furnace, the carbon from the bacteria just vaporises into carbon dioxide, leaving behind pure gold.

The bacteria don’t actually ”make” the gold – they just attract gold that is already dissolved in the groundwater. Now we have absolutely no idea why these bacteria can purify gold to almost 24 carat purity. But maybe now we know what happened to Midas in the old Greek fable, when everything he touched turned to gold. He might have been a victim of accidental genetic engineering, when he got infected with some Pedomicrobium bacteria. And perhaps there’s a moral for us. If you try to get too much gold, it will just suffocate you.

 

abc.net

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