Placer mining for alluvial gold has been around for centuries. As a water-flow slowly erodes rocks and minerals, gold flakes can get caught up in the mix. By carefully filtering this water, it’s possible to make a small fortune in gold. “Panning for gold” was traditionally done by hand, but in the early 1900s, the process was dramatically industrialized with gold dredges.
Gold dredging takes the concept of gold panning and supersizes it. The front end of a gold dredge is like a conveyor belt of buckets that are filled (via suction or scooping) with water and sediment. The contents are dumped onto a rotating steel filter that allows small materials, like gold flakes, to pass through. The small materials are further filtered through a sluice box to get the highest yield of gold. Rocks and other filtered sediment are dumped out of the back of the gold dredge and back into the water source.
The Discovery Channel hosts two reality shows about gold dredging called Bering Sea Gold and Bering Sea Gold: Under The Ice. One show covers the summer season, and the other covers the winter season when most of the sea is iced over. Both shows detail the working lives of multiple gold dredging crews operating out of Nome, Alaska. Millions of years of glacial runoff have made the nearby Bering Sea rich with placer gold deposits. However, dredging operations can be costly and dangerous. Specialized equipment is required, and the Bering Sea is quite treacherous – which contributes to the shows drama. The shows track the amount of gold found by each crew, which varies wildly. As an example, one crew recovered about 766 oz. of gold in season one, while another crew managed only 0.75 oz. Spreads like that between crews appear to be consistent from season to season – so it’s all or nothing for these brave prospectors. Even if these crews don’t strike it rich with their gold dredges, they at least find fame on television!
Last year, Sotheby’s auctioned the 12.03 carat "Blue Moon" diamond for a record setting $48.5 million. That record has already been smashed by the 14.62 carat "Oppenheimer Blue" diamond, which sold at auction for $57.5 million last May.
The emerald cut blue diamond gets its name from its previous owner, Sir Philip Oppenheimer, the former head of De Beers’ Central Selling Organisation. When accounting for the diamond’s enormous price tag, François Curiel, chairman of Christie’s Asia Pacific and China, probably put it best, saying “Philip Oppenheimer could have had any diamond in the world, and this is the one he chose. [. . .] It is the gem of gems.” According to Curiel, the Oppenheimer Blue’s sale price makes it the most expensive jewel, diamond, blue diamond, and colored diamond ever sold at auction.
If you want to split hairs though, the Blue Moon had a higher per carat sale price: $4.02 million vs. $3.9 million. Additionally, the Blue Moon has a clarity grade of IF (internally flawless) while the Oppenheimer Blue has a grade of VVS1 (Very, Very Slightly Included).
How long will this record hold? Only time will tell.
One of the hallmarks of genuine gold is just how heavy it is. However, scientists at the Swiss Federal Institute of Technology in Zurich have completely flipped this concept by creating a formation of gold that makes it 1000 times lighter than bullion of equal volume.
These lightweight properties come from aerogel – a porous, ultralight material created by removing the liquid component from a gel (which could be made by a variety of chemicals) and replacing it with a gas. According to their research, the scientists created gold aerogel by heating milk proteins until they began to form ultra-fine fibers, which were then placed in a solution of gold salts. The fibers interlaced themselves into a basic structure, onto which the gold simultaneously crystallized to form a gel-like network of gilded fibers. The scientists then used supercritical drying with carbon dioxide to remove the liquid from the gel without damaging the fiber network.
The result is a completely homogenous mixture of about 80% gold and 20% milk protein fibers (or, about 20kt gold). It looks solid to the naked eye, but because of its porous structure, gold aerogel is actually 98% air.
There are a few possible applications for this bizarre material. For instance, because gold aerogel is porous, it has a huge surface area – which could make it an extremely efficient catalyst.