Archive for the ‘gold’ Category

F R W van de Goot, R L ten Berge, R Vos
The Journal of Clinical Pathology

In 1599, a Spanish governor in early colonial Ecuador suffered this fate. Native Indians of the Jivaro tribe, unscrupulously taxed in their gold trade, attacked the settlement of Logrono and executed the gold hungry governor by pouring molten gold down his throat. Pouring hot liquids or metals, such as lead or gold, into the mouth of a victim was a practice used on both sides of the Atlantic Ocean, by the Romans and the Spanish Inquisition among others.

Several sources mention the bursting of internal organs. The question remains whether this is actually the case and, also, what the cause of death would be. To investigate this, we obtained a bovine larynx from a local slaughter house (no animal was harmed or killed specifically for this purpose). After fixing the larynx in a horizontal position to a piece of wood and closing the distal end using tissue paper, 750 g of pure lead (around 450°C) was heated until melting and then poured into the larynx. Immediately, large amounts of steam appeared at both ends of the specimen, and the clot of tissue paper was expelled with force by the steam. Within 10 seconds, the lead had congealed again, completely filling the larynx.

After cooling, cross sections of the larynx were made, and formalin fixed, paraffin wax embedded slides of the laryngeal wall were observed under the light microscope. The laryngeal mucosa was found to be totally absent, and coagulation necrosis of the underlying chondroid and striated muscle was seen at a maximum depth of 1 cm.

Based on these findings, we suggest that the development of steam with increasing pressure might result in both heat induced and mechanical damage to distal organs, possibly leading to over inflation and rupture of these organs. Direct thermal injury to the lungs may lead to instantaneous death, as a result of acute pulmonary dysfunction and shock. Even if this is not the case, the development of a “cast” (once the metal congeals again) would completely block the airways, thus suffocating the victim.

In conclusion, we have shown that in the execution method of pouring hot liquefied metals into the throat of a victim, death is probably mediated by the development of steam and consequent thermal injury to the airways.

http://jcp.bmj.com/content/56/2/157.full

gold-ed
The tyrannosaur of the minerals, this gold nugget in quartz weighs more than 70 ounces (2 kilograms).

Earthquakes have the Midas touch, a new study claims.

Water in faults vaporizes during an earthquake, depositing gold, according to a model published in the March 17 issue of the journal Nature Geoscience. The model provides a quantitative mechanism for the link between gold and quartz seen in many of the world’s gold deposits, said Dion Weatherley, a geophysicist at the University of Queensland in Australia and lead author of the study.

When an earthquake strikes, it moves along a rupture in the ground — a fracture called a fault. Big faults can have many small fractures along their length, connected by jogs that appear as rectangular voids. Water often lubricates faults, filling in fractures and jogs.

About 6 miles (10 kilometers) below the surface, under incredible temperatures and pressures, the water carries high concentrations of carbon dioxide, silica and economically attractive elements like gold.

During an earthquake, the fault jog suddenly opens wider. It’s like pulling the lid off a pressure cooker: The water inside the void instantly vaporizes, flashing to steam and forcing silica, which forms the mineral quartz, and gold out of the fluids and onto nearby surfaces, suggest Weatherley and co-author Richard Henley, of the Australian National University in Canberra.

While scientists have long suspected that sudden pressure drops could account for the link between giant gold deposits and ancient faults, the study takes this idea to the extreme, said Jamie Wilkinson, a geochemist at Imperial College London in the United Kingdom, who was not involved in the study.

“To me, it seems pretty plausible. It’s something that people would probably want to model either experimentally or numerically in a bit more detail to see if it would actually work,” Wilkinson told OurAmazingPlanet.

Previously, scientists suspected fluids would effervesce, bubbling like an opened soda bottle, during earthquakes or other pressure changes. This would line underground pockets with gold. Others suggested minerals would simply accumulate slowly over time.

Weatherley said the amount of gold left behind after an earthquake is tiny, because underground fluids carry at most only one part per million of the precious element. But an earthquake zone like New Zealand’s Alpine Fault, one of the world’s fastest, could build a mineable deposit in 100,000 years, he said.

Surprisingly, the quartz doesn’t even have time to crystallize, the study indicates. Instead, the mineral comes out of the fluid in the form of nanoparticles, perhaps even making a gel-like substance on the fracture walls. The quartz nanoparticles then crystallize over time.

Even earthquakes smaller than magnitude 4.0, which may rattle nerves but rarely cause damage, can trigger flash vaporization, the study finds.

“Given that small-magnitude earthquakes are exceptionally frequent in fault systems, this process may be the primary driver for the formation of economic gold deposits,” Weatherley told OurAmazingPlanet.

Quartz-linked gold has sourced some famous deposits, such as the placer gold that sparked the 19th-century California and Klondike gold rushes. Both deposits had eroded from quartz veins upstream. Placer gold consists of particles, flakes and nuggets mixed in with sand and gravel in stream and river beds. Prospectors traced the gravels back to their sources, where hard-rock mining continues today.

But earthquakes aren’t the only cataclysmic source of gold. Volcanoes and their underground plumbing are just as prolific, if not more so, at producing the precious metal. While Weatherley and Henley suggest that a similar process could take place under volcanoes, Wilkinson, who studies volcano-linked gold, said that’s not the case.

“Beneath volcanoes, most of the gold is not precipitated in faults that are active during earthquakes,” Wilkinson said. “It’s a very different mechanism.”

Understanding how gold forms helps companies prospect for new mines. “This new knowledge on gold-deposit formation mechanisms may assist future gold exploration efforts,” Weatherley said.

In their quest for gold, humans have pulled more than 188,000 tons (171,000 metric tons) of the metal from the ground, exhausting easily accessed sources, according to the World Gold Council, an industry group.

http://www.livescience.com/27953-earthquakes-make-gold.html

gold

Mythical King Midas was ultimately doomed because everything he touched turned to gold. Now, the reverse has been found in bacteria that owe their survival to a natural Midas touch.

Delftia acidovorans lives in sticky biofilms that form on top of gold deposits, but exposure to dissolved gold ions can kill it. That’s because although metallic gold is unreactive, the ions are toxic.

To protect itself, the bacterium has evolved a chemical that detoxifies gold ions by turning them into harmless gold nanoparticles. These accumulate safely outside the bacterial cells.

“This could have potential for gold extraction,” says Nathan Magarvey of McMaster University in Hamilton, Ontario, who led the team that uncovered the bugs’ protective trick. “You could use the bug, or the molecules they secrete.”

He says the discovery could be used to dissolve gold out of water carrying it, or to design sensors that would identify gold-rich streams and rivers.

The protective chemical is a protein dubbed delftibactin A. The bugs secrete it into the surroundings when they sense gold ions, and it chemically changes the ions into particles of gold 25 to 50 nanometres across. The particles accumulate wherever the bugs grow, creating patches of gold.

But don’t go scanning streams for golden shimmers: the nanoparticle patches do not reflect light in the same way as bigger chunks of the metal – giving them a deep purple colour.

When Magarvey deliberately snipped out the gene that makes delftibactin A, the bacteria died or struggled to survive exposure to gold chloride. Adding the protein to the petri dish rescued them.

The bacterium Magarvey investigated is one of two species that thrive on gold, both identified a decade or so ago by Frank Reith of the University of Adelaide in Australia. In 2009 Reith discovered that the other species, Cupriavidus metallidurans, survives using the slightly riskier strategy of changing gold ions into gold inside its cells.

“If delftibactin is selective for gold, it might be useful for gold recovery or as a biosensor,” says Reith. “But how much dissolved gold is out there is difficult to say.”

Journal reference: Nature Chemical Biology, DOI: 10.1038/NCHEMBIO.1179

http://www.newscientist.com/article/dn23129-bug-protects-itself-by-turning-its-environment-to-gold.html?cmpid=RSS|NSNS|2012-GLOBAL|online-news

_65340550_goldnugget
An amateur prospector in the Australian state of Victoria has astonished experts by unearthing a gold nugget weighing 5.5kg (177 ounces)

The unidentified man, using a handheld metal detector, found the nugget on Wednesday, lying 60cm underground near the town of Ballarat.

Its value has been estimated at more than A$300,000 ($315,000: £197,000).

Local gold experts say gold has been prospected in the area for decades, but no such discovery had been made before.

“I have been a prospector and dealer for two decades, and cannot remember the last time a nugget over 100 ounces (2.8kg) has been found locally,” said Cordell Kent, owner of the Ballarat Mining Exchange Gold Shop.

“It’s extremely significant as a mineral specimen. We are 162 years into a gold rush and Ballarat is still producing nuggets – it’s unheard of.”

A video of the Y-shaped nugget was posted on YouTube on Wednesday by user TroyAurum.

He wrote that the man who found it had said it “sounded like the bonnet of a car through the headphones.

“It was lying flat (broad side up) and he carefully dug it up.”

Gold currently trades in Australia at about A$1,600 per ounce, meaning the discovery would be worth about A$283,200, but its rarity and the fact it weighs more than a kilogram would add a premium, said Mr Kent.

He told Australian media the prospector had been using a state-of-the-art metal detector, which meant he was able to find the gold relatively deep underground in an area which had been searched many times in the past.

The man had only made small finds before, he said, but was a “person that really deserved it”.

“A finding like this gives people hope. It’s my dream to find something like that, and I’ve been prospecting for more than two decades,” the Ballarat Courier quoted him as saying.

“I’ve got no doubt there will be a lot of people who will be very enthusiastic about the goldfields again, it gives people hope,” said Mr Kent.

“There’s nothing like digging up money, it’s good fun.”

http://www.bbc.co.uk/news/world-asia-21055206

Authorities in Carson City recently made an astounding discovery in the home of a local recluse whose body was found in his residence. Walter Samaszko Jr. had left only $200 in his bank account. But hidden throughout the house were other treasures – including gold bars and coins valued at $7 million.

“You never anticipate running into anything like this,” Carson City Clerk-Recorder Alan Glover told the Los Angeles Times. “It was a run-of-the-mill 1,200-square-foot tract home that still had orange shag carpet. This guy was everybody’s next-door neighbor.”

Samaszko, 69, was described by officials as a loner who went about his business and had few friends. He had been dead at least a month when neighbors called authorities. The victim, who suffered from heart trouble, had lived in the house since the 1960s, and his mother lived with him until her death in 1992.

Glover, who also serves as the local public administrator, was tasked with dealing with the effects of a man who had left no will and had no known living relatives. But during the home cleanup, workers struck gold.

“He was a hoarder – there was everything inside that home you could think of,” Glover said. “The workers found a crawl space from the garage. That led to everything else.

“He was apparently buying gold from a local coin dealer. We found it in sealed boxes marked ‘books.’ We also found gold wrapped in tinfoil stored in ammunition boxes,” Glover told The Times. “There was just more and more. We found a family silver set with rolls of U.S. $20s and Mexican five peso coins.”

The gold coins had been minted as early as the 1840s in such countries as Mexico, England, Austria and South Africa, he said.

Based on just the weight of the gold, Glover estimates the value at $7 million. Because some of the coins appear to be collector items, the value could go much higher, he said.

Officials eventually used a metal detector to search the backyard to make sure they had left no coin uncovered. Samaszko also had stock accounts of more than $165,000 and another $12,000 in cash at the house.

Then came the task of finding relatives. Investigators used list of people who attended Samaszko’s mother’s funeral to track down a first cousin who lives in San Rafael, Calif.

“This will be good for her,” Glover said. “She’s a substitute school teacher who lives in an apartment.”

He said the deceased remains an enigma. “He didn’t socialize. He wasn’t exactly a hermit – he shopped for groceries and talked with at least one elderly neighbor. In his garage was a 1968 Mustang he bought new.”

“He didn’t belong to anything. He just went his own way, with all that gold.”

http://www.latimes.com/news/nation/nationnow/la-na-nn-carson-city-gold-20120917,0,5763811.story