Clean, disinfected water is essential for a good life, but millions of people around the world lack access to it. Researchers at the Cardiff University plan to change this state of affairs with an on-site disinfection approach that is massively more efficient than our current disinfection approaches. The method relies only on atmospheric hydrogen, oxygen, and a gold-palladium catalyst.
The new method aims to provide clean, safe water for consumption and hygiene in areas without access to such resources or reliable disinfection methods. All in all, it could help improve life for billions of people who are struggling with lack of water or water insecurity.
“The significantly enhanced [anti-viral and anti-bacterial] activities achieved when reacting hydrogen and oxygen using our catalyst, rather than using commercial hydrogen peroxide or chlorination, shows the potential for revolutionizing water disinfection technologies around the world,” says Professor Graham Hutchings, Regius Professor of Chemistry at the Cardiff Catalysis Institute, co-author of the paper.
The gold-palladium catalyst allows for hydrogen and oxygen atoms in the air to merge into hydrogen peroxide. This is a common chemical produced in huge quantities around the world which also sees heavy use as a disinfectant. Over four million tons of the compound are produced globally each year.
Typically, hydrogen peroxide is produced at one site and used (for various purposes, including water disinfection) at another. This means it requires storage and transport before use, so hydrogen peroxide is often mixed with other chemicals that stabilize it and keep it fresh until it’s used. While these do perform their intended role, they also cut down its efficiency as a disinfectant (since it’s now, essentially, diluted).
One alternative to this approach is to use chlorine as a disinfectant — add enough of it to water and it’ll kill most pathogens swimming their way around in there, just like hydrogen peroxide does. However, chlorine can react with naturally occurring chemicals in the water creating compounds that can be toxic to humans.
The novel approach however works around these issues by producing the disinfecting agent — hydrogen peroxide — at the point where it is used. The team first tested the efficiency of commercially-available hydrogen peroxide and chlorine in disinfecting water, and then compared this to the efficiency of their catalytic method. All of them were compared based on their ability to destroy Escherichia coli, a common bacteria species, under identical conditions. After this quantitative step, a qualitative step followed, where the team investigated exactly how each method killed the germs.
First off, their method proved to be the most effective, being 10,000,000 times more potent at killing the bacteria per unit of volume than hydrogen peroxide, and over 100,000,000 times more effective than chlorine per unit of volume. It also killed the bacteria faster than either of the two other methods.
Its secret seems to be that the reaction which creates the hydrogen peroxide also produces reactive oxygen species (ROS), highly-reactive compounds that bind to other chemicals, degrading them in the process. Bacteria are also made of chemicals — hence, they’re also being degraded. This process is the same one that makes us grow ‘old’ with age.
Interestingly enough, the team found that these ROSs are what’s killing the bacteria and other pathogens, not the hydrogen peroxide itself.
The team notes that an estimated 785 million people around the world lack access to water, and around 2.7 billion experience water scarcity for at least one month every year. Inadequate sanitation, which is also powered by lack of clean water, affects a further 2.4 billion people worldwide and can lead to a host of water-borne illnesses.
This on-site disinfection method could help all of those people finally have reliable access to clean water for drinking, washing, and any other need they might have. Hopefully, the team’s work will quickly find its way into practice.
“We now have a proven one-step process where, besides the catalyst, inputs of contaminated water and electricity are the only requirements to attain disinfection.”Crucially, this process presents the opportunity to rapidly disinfect water over timescales in which conventional methods are ineffective, whilst also preventing the formation of hazardous compounds and biofilms, which can help bacteria and viruses to thrive.”
The paper “A residue-free approach to water disinfection using catalytic in situ generation of reactive oxygen species” has been published in the journal Nature Catalysis.
New research is aiming to bring color back into the lives of the color-blind.
Color blindness can manifest itself in several ways, from people seeing certain colors in muted shades to not perceiving some at all. Needless to say, this is not the most enjoyable way to live your life and can cause real issues with color-cues, such as difficulties navigating a traffic light. Some of our fixes so far include tinted glasses or dyed contact lenses, but they all have their own shortcomings. The glasses can’t be used to also correct vision (so some people need to pick one or the other condition to fix), and the lenses can be unstable, potentially harmful if not used properly.
A new paper, however, reports on a new approach that can help address this issue: infusing contact lenses with gold particles.
Color blindness is a genetic disorder so, for now, our best approach to the issue so far is to treat its symptoms. The main issue with contact lenses employed for this purpose is that, although they are effective in improving red-green color perception, clinical trials have shown that they can leech the pigments they’re dyed with, potentially harming users’ eyes.
The current paper describes how the authors used gold nanocomposite materials to produce lenses with the same effect, but no dye. This process has been used for centuries already to produce ‘cranberry’ glass, they explain, and comes down to how the gold scatters light going through the glass.
In order to produce them, the team put together an even mix of gold nanoparticles and a hydrogel polymer. The end result was a rose-tinted gel that filters light within the 520-580 nm range, which corresponds to the colors red and green. Several types of nanoparticles were tested, and those who were around 40 nm in diameter were the most effective. During lab testing, lenses built with nanoparticles of this size did not clump, nor did they over-filter the color.
The lenses have the same water-retention properties like those of commercial lenses, and were non-toxic to cell cultures in the lab.
After comparing their lenses’ efficiency to those of two commercially-available pairs of tinted glasses and the pink-dyed contact lenses. The gold-infused lenses blocked a narrower band of the visible spectrum, and a similar amount to that of the dyed contact lenses. This suggests that the gold nanocomposite lenses would be effective for people with red-green colorblindness, but without the health concerns.
The lenses will now undergo clinical trials to assess their efficiency, safety, comfort, and practicality with human patients in real-life situations. If they pass, we could see them available commercially.
The paper “Gold Nanocomposite Contact Lenses for Color Blindness Management” has been published in the journal ACS Nano.
Few metals throughout history can boast the same desirability as gold. It has served as a hard currency for virtually every civilization that had access to it, fueled exploration and exploitation, and directly underpinned the dominant economic policy (mercantilism) for at least two centuries.
It is, by and large, one of the most valuable and impactful metals humanity has ever used, despite it being quite soft and very shiny. So what exactly made gold so valuable and expensive, and why did various peoples show such interest in beating it into coins? Surprisingly, it’s not so much the properties that gold has, it’s what other elements don’t have. The fact that it’s pretty and shiny also helps, too. So let’s get into it.
Most transactions today involve either a swap of pieces of paper and plastic, or moving some virtual bits from one account to another. It’s quite a fast and convenient way of buying and selling. On the surface, it’s a very simple process: you give me what I want, I give you these colorful squares in exchange, then we both ride off into the sunset.
But if we delve a bit deeper, this transaction is only made possible by a huge and unseen net of systems and institutions working in concert. For starters, both parties in our hypothetical transaction recognize that the currency involved is desirable and holds value — this is guaranteed by the governments that be. Secondly, money is easy to carry around (portability), either physically in our pocket or on a card, and to count. Thirdly, we know, through various means, that the money swapping hands isn’t fake (it has validity) that it is a finite, often limited, resource (scarcity), and that it won’t rot over time (longevity). Finally, we both know that touching the money won’t kill us — it is safe.
Ultimately, what you want in a coin is for it to be a small but dense repository of value so you can carry a lot of purchasing power easily, long-lasting so you can store it and it won’t just waste away, distinctive (so it’s easy to tell it’s the real deal), in limited supply to some extent (either through natural or policy constraints), and safe to handle.
Which brings us neatly to gold. There are around 118 elements on the periodic table, most of them natural, some of them only seen in the lab for fractions of a second at a time. Not many of them are usable for coinage, because not many of them share in those traits listed above. We’ll look at each of the properties above to understand why certain elements just don’t work as money. However, we’ll leave value out for right now, as it’s a very complex concept that we should look at in a later article.
Portability: elements that are gaseous or liquid at room temperature just don’t make for very convenient money. They’re not very portable, as you need a vessel to carry them in; such vessels can break, in which case your life savings might easily go ‘poof’ or literally down the drain. Around 13 chemical elements take the form of a gas (nitrogen, oxygen, the halogen group, and the noble gases) or liquid (bromine and mercury) natively, so we can cross these off the list.
Denominations would also be a bit hard to pull off with fluid currencies. Let’s say that the units of choice in our make-believe economy are flasks of mercury and flasks of chlorine gas to serve as subdivisions. What if I need to pay someone three-and-a-half bottles of mercury and don’t have any change on hand — do I pour some out? How do I measure it accurately? How do I know you didn’t dilute the ‘coin’ with some other compound? This problem only gets worse with gases.
Finally, all materials react to changes in temperature and pressure — but fluids react the most. Any such currency would probably require special storage conditions, to avoid both physical damage to their containers, as well as any possible losses that would be incurred by changes in temperatures. Carrying coins on your person over long distances would be much more difficult in this case.
In regards to validity, gold has the benefit of being, well, golden. It’s the only elemental metal bearing this color, which means that it’s quite hard to fake. Alloys and minerals like bronze, brass, and pyrite can pass for it, to an extent, but other properties can be used to check whether a coin is made of gold or not. Pure gold is very soft for a metal, so much so that people used to bite coins to check for gold — human teeth enamel has a Mohs hardness of 5, while gold has only 2.5, so your teeth can put a dent in a piece of gold, but not in a gold-plated coin. Most other metals in the periodic table, with some noteworthy exceptions such as copper, are silvery-gray in appearance, so they can, to an extent, be substituted for one another in a coin.
Its longevity is the product of gold’s very, very limited chemical reactivity. Noble metals and noble gases aren’t called ‘noble’ because they’re expensive (although, they are), they’re called that because, like nobles of old, they don’t mingle with the great masses, chemically speaking. Even runner-ups silver and copper get degraded over time — silver tarnishes due to reactions with sulphur compounds in our sweat or other sources, and copper develops patina due to oxygen. Gold doesn’t rust, it doesn’t tarnish, and doesn’t get splotches on it because gold will react with almost nothing. It doesn’t get degraded by virtually any acid, or bacteria, or alkaline solution. To sum it up, there’s not much you can do to damage gold short of throwing it into some King’s Water (aqua regia), which is a mixture of several strong acids.
Scarcity and safety are pretty straightforward: gold is very rare, so people can’t get the raw materials to make their own coins and ruin the economy. Because it’s so chemically inert, touching gold won’t kill you. You can even swallow some up and still be OK, as fancy pastry-shops are happy to remind you. For comparison, think of sodium, which literally explodes on contact with water.
An ideal mix of qualities and faults
So far, so good — but we’ve yet to answer ‘why gold?’. Sure, it’s portable and distinctive, but arguably so is copper. Mercury is very distinctive, even if harder to carry around safely, and lead is very dense even if somewhat silvery. Carbon is safe to handle; platinum or uranium is much rarer. What gives?
Well, here we get to the meat of it: gold (and silver to an extent) is uniquely suited to making coins because it has the right proportions of each trait for the time it was used. It’s rare, but not impossible to find and extract. It is supremely long-lasting and safe, easy to verify and carry, easy to work into sanctioned shapes (coins).
Is uranium rarer? Probably — but it’s so rare that we simply didn’t know it existed for the longest time, and it will probably slowly kill you, which is not ideal. Platinum is just as if not less reactive than gold, but it’s way scarcer on Earth, and requires much, much higher temperatures (read: advanced tech and know-how) to extract and process. Carbon is just as safe, but it’s lying around quite literally everywhere, so it’s worthless as coinage. And so on.
Gold imposed itself because it had just the right amount of each of these traits to make it an attractive option. It’s really pretty to look at and shiny, which can only help, as does gold’s softness — allowing for official, state-guaranteed coins to be minted with the proper markings. Silver and copper have established themselves as the runner-up metals for coinage throughout history as they share some of the properties of gold, but not enough to put them on equal footing: silver degrades somewhat and is much less distinctive, while copper degrades and is too abundant to be properly controlled by authorities.
Still, as history has shown, gold is a workable but not ideal medium for an economy. It’s durable and rare enough to be used as a placeholder for value but there’s only a limited amount of gold that’s practically accessible to humanity on Earth. Things will go swimmingly while your economy is small, but, eventually, you mine all the gold out. After that you can’t make more money to accommodate demand, you get deflation (prices drop), the economy grinds to a halt and then there’s riots. Not good.
The reverse of the coin is that you can also have too much gold. It’s a real problem, I assure you, as Spain can attest. After discovering the Americas, Spain set to work becoming ridiculously rich in the 15th and 16th through a combination of exploiting the locals and treasure fleets. These were not named in jest — they were, to the fullest extent of the word, fleets of ships, all laden with treasures, all coming to Spain.
“A single galleon might carry 2 million pesos [1 peso = ~25 grams of silver]. The modern approximate value of the estimated 4 billion pesos produced during the [300-year] period would come to $530 billion or €470 billion (based on silver bullion prices of May 2015),” Wikipedia explains about these fleets.
Part of these treasures were goods including spices, lumber, skins, and all manner of nice, exotic things from the Americas; but a large part was represented by silver and gold, mined for cheap. Europe’s economies at the time were still using gold (and silver to an extent) as their standard currency. This means that prices all over the continent were directly determined by how much each country had in store. Mercantilism, the idea that a country becomes richer by exporting more than it imports and gaining gold (and silver) from its partners would form out of this relationship.
But when you have a metal underpinning your currency, keeping a balance between how much of it you hoard and how productive your economy is becomes vital. To give you an idea of just how important this relationship is, know that Spain quickly became one of the, if not the, richest country in Europe at the time. It had so much money by the end of it that the Spanish crown had been throwing it away with both arms for almost two centuries — paying off their national debt, funding religious wars or naval wars with England, colonization of other continents, expensive building projects, fine imports — and they still couldn’t spend it fast enough.
Spain saw massive levels of inflation by the 17th century, to such an incredible extent that the crown had declared bankruptcy (they were the first royal rulers to ever do so) repeatedly, and there is cause to believe that these levels of high inflation affected the rest of Europe, at least Western Europe. It had so much gold relative to goods and services in its economy that it wasn’t really scarce anymore. Coins lost value, prices went right up, the economy stalled because nobody could afford to buy anything, and merchants couldn’t lower prices without incurring a loss. Then the economy ground to a halt and there were riots. Again — not good.
A word of ending
Gold is, to this day, seen as a solid repository of value. But the inability to control its supply (to either increase or decrease it) when needed shackled governments and rulers in regards to their fiscal policy. Once you link your coinage to gold and silver, your economy is at the mercy of how much of them is available in your area.
In olden, golden times, this wasn’t much of an issue; economies were pretty small, local things that moved quite slowly, had low output, and limited technological ability. Gold’s longevity, scarcity, portability, the fact that it was verifiable and safe to use made it an ideal tender, despite its limited supply. There wasn’t a technological base to design artificial money that had those traits, so we used a naturally occurring substance instead.
Today, although its properties haven’t changed and there’s more gold around than ever, it simply is too restrictive; economies are fast, dynamic, with massive outputs and impressive technical possibilities. In this world, being portable, safe, and long-lasting is not enough to keep up with economic reality — so we switched to something that’s all of that, but only artificially scarce.
Gold’s properties made it ideal for the minting of coins, and I hope you gained a better understanding of just what makes a good coin. I’ve done my best to try and discuss this topic without touching on concepts of market value or price, as they’re a whole different kettle of fish that we may open up soon. But as is always the case, gold has value because people say it has value — for its uses, its looks, or its association with status, wealth, and power.
One million times thinner than a human fingernail — that’s how thin is the new form of gold created by a group of scientists at the University of Leeds. It’s the thinnest unsupported gold ever created.
The material is essentially regarded as 2-D (like graphene) because it comprises just two layers of atoms sitting on top of one another. This form gives the newly discovered gold the potential to be used more efficiently, with wide-scale applications in the medical and electronic industries.
flakes are flexible, which means they could be used in bendable screens,
electronic inks and transparent conducting displays, plus tests indicate that
the material is 10 times more efficient as a catalytic substrate than the
currently used gold nanoparticles.
“This work amounts to a landmark achievement. Not only does it open up the possibility that gold can be used more efficiently in existing technologies, but it is also providing a route which would allow material scientists to develop other 2-D metals,” said Dr. Sunjie Ye, lead author of the paper, published in the journal Advanced Science.
the gold nanosheet takes place in an aqueous solution and starts with
chloroauric acid, an inorganic substance that contains gold. It is reduced to
its metallic form in the presence of a ‘confinement agent’ – a chemical that
encourages the gold to form as a sheet, just two atoms thick.
Because of the gold’s nanoscale dimensions, it appears green in water—and given its shape, the researchers describe it as gold nano-seaweed. Images taken from an electron microscope reveal the way the gold atoms have formed into a highly organized lattice. Other images show gold nano-seaweed that has been artificially colored.
The invention billed as a “landmark achievement” by researchers, also sheds more light on the creation of 2D materials altogether. According to the team, the method used to create the gold “could innovate nanomaterial manufacturing,” and the researchers are now focusing on ways to scale up the process.
Graphene, for example, was the much-lauded poster child of 2D materials when it was created in 2004 — but has faced a number of hurdles in large-scale use. With 2D gold, however, its potential is much clearer, researchers say.
“I think with 2-D gold we have got some very definite ideas about where it could be used, particularly in catalytic reactions and enzymatic reactions,” Professor Stephen Evans, who supervised the research, said. “We know it will be more effective than existing technologies—so we have something that we believe people will be interested in developing with us.”
Researchers at the University of Leeds have created the thinnest unsupported gold plate ever — just two atoms thick.
The nanoscale gold sheet. Image has been artificially colored. Image credits University of Leeds.
The team reports that the thickness of their gold plate is just 0.47 nanometres, making it one million times thinner than a human fingernail. For comparison, the thickness of a human strand of hair ranges between 17 to 181 nanometres. The researchers call the plate ‘2-D’ gold because it’s just two-atoms thick.
“This work amounts to a landmark achievement,” says lead author Dr. Sunjie Ye, from Leeds’ Molecular and Nanoscale Physics Group and the Leeds Institute of Medical Research.
“Not only does it open up the possibility that gold can be used more efficiently in existing technologies, it is providing a route which would allow material scientists to develop other 2-D metals. This method could innovate nanomaterial manufacturing.”
As the plate is built from only two layers of atoms, all of them are surface atoms, i.e. none of them are completely covered by others. This is especially important for catalysts, whose efficiency varies with the amount of surface area they can present to the environment.
Electron microscope image showing the arrangement of gold atoms on the nanosheet. Image credits University of Leeds.
Laboratory tests show that the 2-D gold plate is 10 times more efficient as a catalytic substrate than the currently used gold nanoparticles. These gold nanoparticles are 3-D materials and the majority of their atoms reside in their bulk rather than on the surface, so they are inactive.
In addition to pointing the way towards new, better catalysts for a range of industrial processes, the material could also have applications in the medical device and electronics industries. The team writes that it can also form the basis of artificial enzymes that could be applied in rapid, point-of-care medical diagnostic tests and in water purification systems.
The team’s synthesis process takes place in a watered-down solution of chloroauric acid, an inorganic substance that contains gold. This substance is then reduced to produce metallic gold using a ‘confinement agent,’ a chemical that encourages the gold to form as a very thin sheet.
Because at this point the gold particles are still in the nanoscale, it appears green in the water. Also due to the resulting shapes, the team describes it as ‘gold nanoseaweed’.
Image credits University of Leeds.
Professor Stephen Evans, head of the Leeds’ Molecular and Nanoscale Research Group and lead researcher on the project, says that the findings could help several industries cut down on production costs due to the high surface-to-volume ratios of the 2-D gold sheets.
“Gold is a highly effective catalyst. Because the nanosheets are so thin, just about every gold atom plays a part in the catalysis. It means the process is highly efficient,” says Professor Evans.
“Our data suggests that industry could get the same effect from using a smaller amount of gold, and this has economic advantages when you are talking about a precious metal.”
Furthermore, the sheets are also flexible despite their extreme thinness. This makes them ideal for a variety of applications in electronics, especially in the building of components, bendable screens, electronic inks, or transparent conducting displays.
Professor Evans says there are many similarities between the 2-D gold and graphene, the first 2-d material ever created in the lab. However, he also cautions that the transition from new materials to working products takes a long time, and that “you can’t force it to do everything you might like to”.
“With graphene, people have thought that it could be good for electronics or for transparent coatings — or as carbon nanotubes that could make an elevator to take us into space because of its super strength,” he explains. “I think with 2-D gold we have got some very definite ideas about where it could be used, particularly in catalytic reactions and enzymatic reactions.”
“We know it will be more effective than existing technologies, so we have something that we believe people will be interested in developing with us.”
The paper “Sub‐Nanometer Thick Gold Nanosheets as Highly Efficient Catalysts” has been published in the journal Advanced Science.
Medical nanobots are one step closer, as researchers developed simple nanorobots that can be propelled through blood to clear out bacteria and toxins.
Image credits Mate Marschalko / Flickr.
A team of engineers from the University of California San Diego has developed a class of ultrasound-powered robots that can scrub blood clean of bacteria and the toxins they produce. While still simple, the proof-of-concept nanobots could pave the way towards safe and rapid methods of decontaminating biological fluids — even in the bodies of living patients.
The team builds their nanorobots out of gold nanowires coated with platelet and red blood cell membranes. This hybrid membrane is what gives the nanites the ability to clear out biological contaminants. The platelet membrane binds to pathogens such as the antibiotic-resistant strain of Staphylococcus aureus, MRSA, while the red blood cell membranes can absorb and neutralize toxins produced by bacteria.
The gold nanobody is what lets the researchers move the bots around. The metal responds to ultrasound, giving the team the means to power them through the bloodstream without the use of engines or fuel. The bots need to be mobile in order to more efficiently mix with a fluid sample, speeding up the process of detoxification.
The nanobots were created using processes pioneered by the teams of Joseph Wang and Liangfang Zhang, professors in the Department of NanoEngineering at the UC San Diego Jacobs School of Engineering. Wang’s team designed and built the nanobots and the means of ultrasound-powered propulsion, while Zhang’s team developed the process used to coat these in natural cell membranes.
“By integrating natural cell coatings onto synthetic nanomachines, we can impart new capabilities on tiny robots such as removal of pathogens and toxins from the body and from other matrices,” said Wang.
“This is a proof-of-concept platform for diverse therapeutic and biodetoxification applications.”
Furthermore, the natural membranes prevent the nanobots from being ‘biofouled’ — a process by which proteins cake onto the surface of a foreign body, which would prevent the nanobots from functioning. The hybrid membranes were created from natural membranes, separated in one piece from platelets and red blood cells. These were then blasted with high-frequency sound waves, causing them to fuse together.
The nanobot binding to and isolating a pathogen. Image credits Fernández de Ávila et al., 2018, Science Robotics.
The robots’ bodies were constructed by then applying these membranes to gold nanowires through chemical means.
The finished devices are roughly 25 times smaller than the width of a hair, the team writes. Ultrasound waves can propel them up to 35 micrometers per second in blood. They were successful in cleaning blood samples contaminated with MRSA and associated toxins — after 5 minutes of being injected, the levels of bacteria and toxins were three times lower in treated samples than untreated samples.
If you’re like me and dream all starry-eyed about the day we’ll treat ourselves with nanobots, this research might make you feel quite happy inside. However, this work is at a very early stage. It’s also focused on something different — the team notes that, while their current nanobots can be used to treat MRSA in blood samples, they aim to have a device that can detoxify all kinds of biological fluids.
We still have a ways to go until then. For the near future, the team hopes to test their devices in live animal models, and to devise a way of creating the robot bodies out of biodegradable materials instead of gold.
The paper “Hybrid biomembrane–functionalized nanorobots for concurrent removal of pathogenic bacteria and toxins” has been published in the journal Science Robotics.
The wreck of the San José, a gold-laden Spanish galleon sunk in 1708, has been identified thanks to its distinctive bronze cannons.
To confirm the wreck’s identity, REMUS descended to just 30 feet above the wreck to capture photos of its cannons. Image credits Woods Hole Oceanographic Institution.
Around 310 years ago, at the height of the War of Spanish Succession (a conflict that Spain and France were fighting against England), one ship laden with treasure set sail from the Americas towards Europe. Beset by English foes, the ship was sunk with all hands aboard in the Caribbean Sea. Now, the ship’s wreck has been officially identified.
Mind the guns
The identification was made possible by the ship’s onboard artillery: the guns, cast in bronze, still sported their ornate and distinctive dolphin engravings. The cannons were investigated by REMUS 6000, an autonomous underwater vehicle (AUV) that got within 30 feet (9.1 meters) of the shipwreck in 2015, according to Woods Hole Oceanographic Institution (WHOI).
The WHOI had determined the shipwreck’s identity in 2015, but it didn’t have approval from affiliated agencies (Maritime Archaeology Consultants, Switzerland AG, and the Colombian government) to make the findings public until now.
The San José was part of what the Spanish called their ‘treasure’ or ‘silver fleets‘: crafts that would traverse the Atlantic Ocean to shuttle immense riches from the Americas towards Europe, where they would fund Spanish war efforts. Individual fleets were made up of several ships, each highly specialized, to make sure this spoliation went along as smoothly, efficiently, and uninterruptedly as possible. The San José was the largest galleon and flagship of one such treasure fleets. Bristling with 62 guns across its multiple decks made the prospect of attacking the Spanish treasure a very unattractive proposition for both pirates and rival nations.
But hubris, as it often does, would eventually prove to be the galleon’s undoing. While it was the San José’s job to actually ferry the riches every year, the other ships in the fleet were present to guard it against would-be assailants. However, in 1708, as the escorting ships were delayed in linking up with the galleon, Admiral José Fernandez de Santillan, count of Casa Alegre and the ship’s captain, decided to set sail without them.
On June 8, 1708, it was beset upon by four English ships. After a pitched battle, a stray shot ignited the San José’s gunpowder stores — sending the ship, the treasure, and its almost 600-strong crew to the bottom of the sea.
It is, to this day, one of the most expensive maritime losses in the world. The cargo, consisting of gold, silver, and emeralds mined in Peru, is estimated to value between $4 billion and $17 billion today. During the bitter war against England, it would have been a monumental loss for Spain.
The shipwreck was discovered by an international team aboard the Colombian Navy research ship ARC Malpelo on Nov. 27, 2015, at over 2,000 feet (600 meters) deep, near Colombia’s Barú Peninsula. Because the wreck’s identity couldn’t be confirmed at the time of the discovery, the WHOI sent the REMUS 6000 to the site.
“The REMUS 6000 was the ideal tool for the job, since it’s capable of conducting long-duration missions over wide areas,” Mike Purcell, WHOI engineer and expedition leader, said in a statement.
Recordings taken by the autonomous vehicle revealed the ship was partially covered in sediment — however, it also captured the decorative carvings on the cannons on a subsequent dive. From them, Roger Dooley, the lead marine archaeologist at MAC, was able to confirm the ship’s identity, the WHOI adds.
The Colombian government plans to build a museum and conservation laboratory to preserve and display the shipwreck’s contents, including its cannons and ceramics.
An international team of researchers has uncovered the reactionary processes biology uses to bind gold. The process, which is employed by heavy-metal-resistant bacteria, could revolutionize how we extract the precious metal.
Image credits Csaba Nagy.
Most organisms don’t really like high concentrations of heavy metals such as copper or gold, as they are quite toxic and pose a significant threat. However, certain beings, such as the bacterium C.metallidurans, have adapted to withstand very high concentrations with ease. It does this by extracting useful elements from compounds laden with heavy metals and then depositing the toxic bits.
One interesting (and potentially quite lucrative) side-effect of this process is that C. metallidurans excretes pure gold, which coalesces into nuggets. Knowing how fond humans are of shiny things, a team of researchers from the Martin Luther University in Halle-Wittenberg (MLU), the Technical University of Munich (TUM), and the University of Adelaide in Australia have identified the molecular processes that underpin this nuggeting.
The bug with the golden eggs
C.metallidurans is a rod-shaped bacterium that primarily colonizes soils enriched/polluted with numerous heavy metal compounds. While that sounds like the bacterium is a poor judge of real-estate, its choice in soil actually comes with significant perks. Chief among them is that other bacteria don’t want anything to do with this harsh environment. The second is that if you look past the “deadly toxic” aspect, heavy metal compounds are a surprisingly hearty source of energy.
“Apart from the toxic heavy metals, living conditions in these soils are not bad,” explains Professor Dietrich H. Nies, a microbiologist at MLU. “There is enough hydrogen to conserve energy and nearly no competition. If an organism chooses to survive here, it has to find a way to protect itself from these toxic substances.”
It was actually Nies himself, together with co-author Frank Reith, a Professor at the University of Adelaide, who found that C. metallidurans can deposit gold biologically back in 2009. However, they were unable to say why or how it did so — something they addressed in their new paper.
The process actually starts with copper. Copper is a vital trace element for C. metallidurans, however, the form it’s usually found geologically can’t be easily absorbed and processed by the bacteria. So the bacteria unleashes a barrage of chemical processes meant to soften up this copper and convert it to a form that’s easily gobbled up.
Gold enters the bacteria using the same processes and membrane channels as copper, the team reports. These compounds, by and large, resemble the copper ones, and so are processed by the same chemicals the bacterium uses for copper. Also, just like copper, gold becomes very toxic very fast at higher concentrations. The only difference is that C. metallidurans don’t actually want or need gold.
To make sure there isn’t too much of a copper buildup inside its membrane, the bacteria use an enzyme called CupA to pump any excess out, the team reports. However, when both metals are present in the cell, the CupA enzyme becomes suppressed, Nies explains. This poses quite a problem for the bacteria as the two metals “combined are actually more toxic than when they appear on their own.”
To flush out this extra-toxic cocktail, C. metallidurans employs a second enzyme dubbed CopA. This transforms both metals back into their original, hard-to-absorb forms.
“This assures that fewer copper and gold compounds enter the cellular interior,” Nies explains. “The bacterium is poisoned less and the enzyme that pumps out the copper can dispose of the excess copper unimpeded.”
“Another consequence: the gold compounds that are difficult to absorb transform in the outer area of the cell into harmless gold nuggets only a few nanometres in size.”
Gold nugget deposited by the bacteria. Image credits L. Bütof et al., 2018, Metallomics.
The whole process takes toxic gold particles formed by erosion or other weathering processes and turns them into harmless gold nuggets. These nuggets are considered to be secondary gold, so called because they’re generated from primary (geologically-created) gold, broken down from ores and re-deposited.
The research completes our understanding of the biogeochemical gold cycle — the second half of which was largely unknown up to now. This cycle sees a bacterial transformation of primary gold metal into toxic compounds, followed by another, bacteria-powered transformation into secondary metallic gold in the last half of the cycle.
Fully understanding the processes involved in this cycle could help revolutionize the way we extract gold, making the process cleaner and more efficient. The most significant advantages over today’s methods would be the possibility to use poorer ores (with a small percentage of gold) than before and taking mercury and other very toxic compounds out of the extraction process.
The paper “Synergistic gold–copper detoxification at the core of gold biomineralisation in Cupriavidus metallidurans” has been published in the journal Metallomics.
NASA’s new GOLD mission will be studying Earth’s upper atmosphere, some 22,000 miles above the surface, in a bid to give us better GPS and more reliable navigation.
Astronaut John W. Young used a UV camera during the Apollo 16 mission to take this picture of Earth’s disk in far-ultraviolet light. It’s the most recent such picture we have, and it dates all the way back to 1972. GOLD will offer a constant view of Earth’s atmosphere in this spectrum. Image credits NASA.
Earlier today, NASA researchers attended a live feed in which they discussed the agency’s next mission. On January 25th, launch facilities in Kourou, French Guiana will blossom with rocket exhaust. Hitching a ride on the back of the SES-14 communications satellite launching on that day, NASA is also sending a mission to space. GOLD, the Global-scale Observations of the Limb and Disk mission, will analyze the boundary between Earth and outer space. The data will be used to get a better understanding of how it changes over time and, along with another upcoming satellite, called ICON, to determine how space weather affects the highest layers of our atmosphere.
“For years, we’ve been studying the Earth’s upper atmosphere — thermosphere and ionosphere — and we’ve been looking at those in detail from the ground and from low-Earth orbit missions,” said Richard Eastes, the principal investigator for GOLD from the University of Central Florida.
“We wanted to be able to back off and get the big picture, get a whole hemisphere at once. That lets us put things into context that we can’t understand when we’re just looking at one little piece.”
GOLD’s job will be to analyze the ultraviolet radiation emissions of the upper atmosphere. The craft will also be the first one to take a thorough record of the temperatures in these top layers according to Eastes. As such, it will be stationed some 35,500 kilometers (22,000 miles) above the surface in a geostationary orbit — meaning it will match Earth’s rotation to stay in a fixed spot relative to the planet’s surface.
The thermosphere, the part of the atmosphere over than 97 km (60 miles) above Earth’s surface, and the ionosphere, a skin of charged gas formed on the outskirts of our atmosphere as solar radiation strips electrons from atoms (creating ions), are of particular interest for the mission. Our understanding of both these formations is currently limited. For example, we know that it’s heavily influenced by what the sun does — solar flares, for example, can dramatically alter the state of the ionosphere, and influence GPS-like systems. Solar radiation and solar wind hitting Earth’s magnetic field can cause geomagnetic storms and other space weather.
NASA infographic showing the different layers of Earth’s atmosphere. Image credits NASA’s Goddard Space Flight Center / Duberstein.
But scientists are becoming increasingly aware that going-ons on Earth also influence these layers. From commonplace activity, such as whether, to extreme events, such as tsunamis, events taking place below these layers also seem to have a profound effect on their nature, but ones that are still barely known — nevermind understood.
“For example, tsunamis create waves in the air, and those waves move upwards, and the waves could potentially cause changes even at the very boundary between the Earth and space,” said Sarah Jones, GOLD mission scientist at Goddard, during the stream.
“GOLD is studying in particular how to tease out the effects coming from the sun above and Earth below.”
It’s not a pursuit of pure science, either. Our GPS systems and communication infrastructure stand to benefit greatly, should we learn how to accurately map and model these regions. Right now, we only have the capacity to observe changes once every several hours (which is quite poor), and the models at our disposal can predict changes about one day in advance (but are still not beyond errors).
The data beamed back from GOLD will be a gold mine for scientists trying to refine such models. The craft will let us constantly keep tabs on what the upper atmosphere does throughout the day, so we’ll also be able to spot anything going awry much more easily.
ICON (Ionospheric Connection Explorer), GOLD’s partner craft which will be launched later in 2018, will fly through the upper atmosphere at about 560 km (350 miles) to give a detailed look and complement GOLD’s bird-eye view. This remote-sensing coupled with on-site observation will allow researchers to see what’s happening to the boundary between Earth and space in detail and at large. Taken together, the craft will help us understand the processes that shape our planet’s troposphere and ionosphere, and how these, in turn, impact the surface.
Here’s a simulation of the data GOLD is expected be beaming back to NASA. You can even see ICON from up there!
“Not only is it telling us about fundamental science, which is pertinent not just to what happens here in our solar system, but in fact in other solar systems, exoplanet systems — but also, all of this energy and matter interacts with our technology,” Alex Young, the associate director for heliophysics science at Goddard, said during the stream.
“It’s interacting with spacecraft, sometimes disrupting them, and it even creates a really nasty environment for astronauts. Understanding that is important also for space travel near the Earth and through the rest of the solar system.”
French archaeologists have unearthed a breathtaking hoard of medieval riches at the Abbey of Cluny, in Saône-et-Loire. The riches include over 2,200 silver deniers and oboles, 21 Almoravid gold dinars, a signet ring and other gold objects. It’s the largest single collection of silver deniers ever discovered, and the first time European coins were found hidden alongside Arab ones and such a prohibitively expensive object as a signet ring.
The coins as discovered in-situ, and after excavation.
This round of excavation works at the Abbey of Cluny started in 2015 under the supervision of Anne Baud, an academic at the Université Lumière Lyon 2, and Anne Flammin, an engineer at the Centre National de la Recherche Scientifique (CNRS). Working together with colleagues and 9 students enrolled in the Master of Archaeology and Archaeological Science at the Lyon 2 University, they’ve discovered a treasure likely dating from the first half of the 12th century.
Fit for Smaug
The treasure trove consists of over 2,200 European silver coins, most of which were minted at the Abbey, which were stored in a cloth bag — traces of which still remain on some of the coins. Western currency at the time was dominated by the silver denier, and such deniers would likely have been used for everyday purchases.
Inside the bag, archaeologists also found a tightly bound and knotted tanned hide bundle containing 21 Arab gold denars, minted between 1211 and 1311 in Morocco and Spain under Ali ibn Yusuf, a member of the Berber Almoravid dynasty. Gold coins at this time were largely reserved for rare and significant transactions.
Alongside the coins, the team recovered a gold signet ring with “a red intaglio depicting the bust of a god” likely created in the first half of the 12th century, a foil of gold sheet weighing 24 grams that was stored in a case, and a small circular object made of gold.
Knotted tanned hide bundle holding the gold objects.(2) & (4) gold dinars; (3) signet ring with intaglio; (5) contents of knotted tanned hide bundle. Image credits Alexis Grattier / Université Lumière Lyon 2
The finding is exceptional on several counts. For starters, the sheer size and value of the of riches unearthed make this hoard stand out — this is the largest single stash of deniers ever found. It’s also a very unusual to find Arab coins in a monastic setting, both because of their huge value — which prohibited use in anything but the largest transactions — especially at Cluny, which was one of the largest abbeys of Western Europe during the Middle Ages.
The riches help color the history of Cluny Abbey, a historical site open to the public and also raise some very exciting questions. How did this treasure get here, who did it belong to and who brought it? And why was it hidden?
Vincent Borrel, a PhD student at the Archaeology and Philology of East and West (CNRS / ENS) research unit is currently studying the treasure in more detail to identify and date the various pieces with greater precision, hopefully gaining some insight into what the answers to these questions might be.
It was, by far, the most spectacular discovery of 2017. Gravitational waves not only confirmed a theory proposed by Albert Einstein 100 years ago but also opened up a whole new field of observational science. But they’ve done even more: they’ve shown us how gold was formed.
Artistic depiction of spinning / colliding neutron stars. Credits: Los Alamos National Laboratory.
After astronomers observed gravitational waves coming from the collision of two black holes, they’ve now observed the same phenomenon from a different collision: between neutron stars. Neutron stars are the collapsed cores of large stars between 10 and 29 solar masses. After a massive supernova explosion which ejects most of the star’s material, the gravitational collapse compresses the core to incredible densities. Neutron stars are the smallest stars (often measuring only kilometers across), but they’re also the densest. Most models suggest that they comprise almost exclusively of neutrons — hence the name.
For the first time, scientists have observed a collision between two neutron stars. Some 130 light years away, the two stars began an unstoppable dance, drawing closer and closer to each other, until they were spinning around each other more than 500 times per second, distorting space and time as they did so.
The ripples they created spread through the Universe, some of them reaching a planet we call Earth. There, scientists all over the world recorded the observation, realizing its massive importance. Andrew Levan, Professor in the Astronomy & Astrophysics group at the University of Warwick, commented:
“Once we saw the data, we realised we had caught a new kind of astrophysical object. This ushers in the era of multi-messenger astronomy, it is like being able to see and hear for the first time.”
Not only did astronomers record the gravitational waves, but they also used this event to answer several questions. Dr. Samantha Oates, also from the University of Warwick added:
“This discovery has answered three questions that astronomers have been puzzling for decades: what happens when neutron stars merge? What causes the short duration gamma-ray bursts? Where are the heavy elements, like gold, made? In the space of about a week, all three of these mysteries were solved.”
Gold, like most heavier elements, is formed through a process of stellar fusion. In the earlier stages of the universe, only lighter elements like hydrogen and helium existed (in significant quantities, at least). So where did all the others come from?
Well, the early stars burned more and more mass, fusing existing atoms and creating new ones. Going higher and higher on the periodic table, they ultimately reached heavier metals like gold and iron. In a previous article, ZME’s Tibi Puiu explains:
“Finally, as they burnt silicon to make iron, they exploded as a supernova, and for a few short moments, each star would release as much energy as all the regular stars in that galaxy put together. In that cataclysmic explosion, for the first time, atoms of gold were manufactured — and then hurled out into the Universe, along with the other debris from that explosion.”
Scientists had a pretty good idea that this is how gold originated, but this is the first time we’ve seen it live. The neutron stars’ collision created as much gold as the mass of the Earth, and also created heavier elements such as platinum and uranium, pumping them into space.
Dr. Joe Lyman, who was watching the collision at the European Southern Observatory, was the first to alert the community of these findings, emphasizing the importance of having direct confirmation of previous theories.
“The exquisite observations obtained in a few days showed we were observing a kilonova, an object whose light is powered by extreme nuclear reactions. This tells us that the heavy elements, like the gold or platinum in jewellery are the cinders, forged in the billion degree remnants of a merging neutron star.”
I’ve never been a big fan of gold, but knowing how it’s formed somehow makes it much more beautiful. It somehow makes everything much more beautiful.
You’ve probably not given it much thought, but the reason why gold is yellow (or rather, golden) is deeply ingrained in its atomic structure — and it’s because of something called relativistic quantum chemistry. Simply put, gold’s electrons move so fast that they exhibit relativistic contraction, shifting the wavelength of light absorbed to blue and reflecting the opposite color: golden.
Pure gold. Image via Wikipedia.
What is color?
If we want to understand why gold is yellow, we first have to understand what color is in the first place. White light — what we usually simply call light — is a mixture of a lot of colors, all with their individual wavelength. When light bounces off any object, it is reflected, scattered, and absorbed (to some degree). So a wavelength might arrive at the object, but another one may leave it. This is the (simplified) mechanism that is responsible for giving things their color. The human eye absorbs the wavelength and transforms it into color. It should be noted that objects have their own physical color, but the color our eyes see might be somewhat different, depending on a host of contextual (i.e. viewing angle) and biophysical cues (i.e. any disability).
A prism breaks down the white light into its constituents’ respective wavelengths. We see this as different colors.
It wasn’t until Newton that we realized light is the source of color. This fascinated numerous scientists and artists, included James Clerk Maxwell, Hermann von Helmholtz, and even Goethe, who greatly improved our understanding of colors and the effects they have on us. They happened to revolutionize physics in the process, but that’s a story for another time. Back to gold.
The chemistry of gold
If you look at gold in the periodic table, you’d perhaps not think much of it. With an atomic number of 79, it sits almost quietly at the end of a group called the transitional metals (can you spot it?). But if you look at it a bit closer, you’ll start to notice some things. For starters, it sits right below copper (Cu) and silver (Ag), two very important metals in human history, and two metals with which it shares important characteristics.
“Comparing copper metal, silver metal and gold metal with their numerous neighbouring metal atoms has never been a problem, as pure metals have been around for millennia,” said Prof. Dr. Bernd Straub, who published a scientific paper on what gives gold its color.
But unlike silver, copper and pretty much all other metals for that matter, gold doesn’t sport a bland, silvery color. Gold is yellow, so that doesn’t explain much. But perhaps even more interestingly, it sits right before Mercury (Hg), the only liquid metal. Gold’s yellow color and Mercury’s liquid-ness actually have a lot in common.
In chemistry, some things just don’t make sense if you don’t consider quantum mechanics and relativistic mechanics — especially for the heavier elements of the periodic table. So chemistry quickly incorporated these theories into what is called Relativistic quantum chemistry. In this branch of chemistry, one of the most important things is relativistic movement.
Basically, when things start to move at speeds comparable to that of light, we don’t only look at their mass, we look at their relativistic mass. Basically, when things start to move so fast, additional energy cannot substantially increase their speeds, and instead, they start to increase their mass. Technically speaking, everything has a relativistic mass, but because day to day objects move so incomparably slower than the speed of light, this mass is absolutely negligible. Not the same thing can be said for atoms. Well, at least some atoms.
Arnold Sommerfeld calculated that, for a single electron of a standard hydrogen atom, the speed is v ≈ Zc/137. Don’t be afraid, it’s quite simple. The formula basically says that an electron inside an atom will move at a speed approximately equal to the atomic number divided by 137. For gold, we already know that the atomic number is 79. So in this case, electrons would be moving at 58% of the speed of light, which is quite substantial. It means that relativistic effects are clearly noticeable for gold, and these effects are affecting its color.
So, we’re almost there…
Putting it all together
So, now that we understand what color is, we have some basic idea of the chemistry of gold, and we know that relativistic effects are at play, it’s time to get to the bottom of things.
Reflectance vs. wavelength curves for aluminum (Al), silver (Ag), and gold (Au) metal mirrors at normal incidence.
As we said, the electrons of gold, especially in the outermost electron shell, move at relativistic speeds. This outer shell is responsible for chemical behavior and a lot of physical properties, including color. The human eye spectrum varies from wavelengths of about 390 (blue) to 700 nm (red). If you’ll look at the reflectance curve above, you’ll see that gold absorbs a lot of the low wavelengths, the blue. So we’re left with the opposite. The human eye sees electromagnetic radiation with a wavelength near 600 nm as yellow — that’s what gold reflects, and that’s what we’re seeing. Voila! A similar effect occurs in silver but the relativistic effects are lower. Notably, cesium (in pure form) also has a golden streak, due to the same reasons.
Oh, by the way, remember when we discussed about Mercury earlier? It’s similar relativistic effects that are responsible for that.
Scientists found that gold nanoparticles (shown in red , inset) are absorbed from the soil beneath the Eucalyptus tree and concentrated in leaves and twigs. (c) Nature Communications
The old saying “money doesn’t grow on trees” is often recited to remind squandering youth of the value of a hard-earned buck. Things turn really funny when you hear that gold, as in the actual glittering chemical element that money is used to be based on, grows on trees. In Australia, to be more precise, geochemists at CSIRO’s Earth Science and Resource Engineering division in Kensington found that trees that grew on gold deposits had a concentration of gold particles at the surface of their leaves 40 times higher than trees that grew on normal soil.
The tree studied by the researchers led by Mel Lintern, a geochemist with the Commonwealth Scientific and Industrial Research Organisation (Australia’s national science agency), is a certain Eucalyptus tree which grew above a known gold deposit.
The deposit is about the size of a football field and lies at least 30 meters below ground – too little for too much of an effort to be worth the exploitation. What scientists have learned after gathering twigs, bark and a myriad of trees, however, may be of greater value. Imagine prospecting operations that are both cheap and non-invasive: as easy as putting a leaf under a microscope.
You see, after comparing the same vegetation from trees growing 200 meters away from the ore, the researchers found the ‘golden’ Eucalyptus measured 40 times more background gold concentration or 80 parts per billion (ppb).
This find came from a site in Western Australia, so the researchers wanted to see if similar results can be discovered in other areas. In Southern Australia, at another site, the researchers showed that eucalyptus trees growing above a deposit lying 35 meters underground had 20 times more gold in the gummy substances coating their leaves than did trees that grew 800 meters away.
Their data suggested that the trees, which have roots extending up to 40m below ground, had absorbed particles of gold while searching for water during droughts, and transported to their leaves, twigs and bark.
Scientists have known for some time that trees gather tiny gold particles at the surface of their leaves, but the only viable explanation they could find at the time is that these were collected by the leaves from winds carrying and sweeping gold particles found at the surface.
To verify the gold is actually expelled from the soil underneath the trees and not simply gathered from the surface, Lintern and colleagues devised an experimental set-up.
They grew seedlings in greenhouses insulated from airborne dust and watered them with a gold-laced solution. In time, they found the gold accumulated at the surface of the leaves, proving the element was actually absorbed from the soil and expelled later.
Indeed, being a heavy metal, gold may be harmful to trees and the build-up of gold at the leaves’ surface may be the result of a defense mechanism.
“The new research provides “a conclusive set of evidence … from a very nicely constructed set of experiments,” says Clifford Stanley, a geochemist at Acadia University in Wolfville, Canada.
I know what you’re thinking. What if we mine trees? Well, you’d have your work cut out for you. The highest concentration of gold is found in the leaves. If you dry them up, you end up with an even higher concentration. Even so, the largest gold particle the scientists could find was 8 micrometers across or half the width of a human hair. Too thin and too spaced apart. Collecting gold from trees would be too much of a hassle to make anyone bother. But where the gold in trees fails as an ore mine, it shines in its prospecting value.
Engineers could use this information to first measure gold concentration in trees from areas suspected of harboring gold deposits, and only after they find hints would the big guns be called for: geology and geophysics.
The underlying regolith stratigraphy and Au deposit is shown. (c) Nature Communications
Worldwide, new discoveries of the metal are down 45% over the past decade. All the good and easy to find spots are already taken, the next generation of prospecting will require new and ingenious methods to stay on top. Gold growing in trees might find a great part to play.
It’s worth noting that trees aren’t the only unconventional gold prospecting tool. For instance, entomologists at the same CSIRO in Australia found that termites “mine” and stockpile the precious metal while they’re collecting subterranean material for their nests. From the ZME Science article we wrote a while ago:
For the study, entomologist Aaron Stewart, with Australia’s Commonwealth Scientific and Industrial Research Organisation, and colleagues analyzed samples from several termites nests and compared them to soil samples taken from different depths.
Then, by using a mass spectrometer, they found a direct correlation between the amount of gold in the termite nest sample and their proximity to the gold source: the ones closer to the deposit had higher concentrations. A mass spectrometer analyzes the chemical make-up of the sample, by measuring the the mass-to-charge ratio of charged particles.
Also, plants have been used before to find gold – a prospecting technique called gold phytomining (when animals are used to mine it, it’s called biomining).
Using certain hyperaccumulators – plants that have the natural ability to take up through their roots and concentrate metals such as nickel, cadmium, and zinc in their leaves and shoots – scientists found that under certain chemical conditions, gold solubility can be forced. Some have proposed using phytomining to extract gold, essentially growing gold but it’s been found to be unfeasible. This latest research, however, is the first to show gold grows on trees.
The natural gold particles growing in Eucalyptus trees finding was reported in a paper published in the journal Nature Communications.
Editorial note: The metaphor “gold grows on trees” shouldn’t be taken literally. Gold particles are absorbed from the soil beneath the tree and then expelled at the surface of vegetation.
The first images of Viking treasure, stashed in a pot more than 1,000 years ago and buried in a field in Galloway, have been made public by the conservators working to preserve them. The items, including six silver disk brooches, a gold ingot and Byzantine silk, are not currently on display.
Metal detectorist Dered McLennan found the hoard in Galloway in 2014. Since then a lot of effort has been put into removing and preserving the pot and items, dated from the 9th or 10th century BC.
The pictures give the public a chance to see the items for the first time as they are not currently on display. Image credits Historic Environment Scotland.
And it’s a literal pot of gold. Inside, archaeologists found six silver Anglo-Saxon disc brooches and one from Ireland, silk traced back to Byzantium (modern-day Istanbul,) a gold ingot as well as gold and crystal objects carefully wrapped in pieces of cloth. Historic Environment Scotland are working together with the Treasure Trove Unit and the Queen’s and Lord Treasurer’s Remembrancer (QLTR) to fund the exhaustive conservation efforts.
“Before removing the objects we took the rather unusual measure of having the pot CT scanned, in order that we could get a rough idea of what was in there and best plan the delicate extraction process,” said Richard Welander of Historic Environment Scotland.
“That exercise offered us a tantalising glimpse but didn’t prepare me for what was to come.”
A silver brooch from Ireland was found inside the pot. Image credits Santiago Arribas Pena.
“These stunning objects provide us with an unparalleled insight to what was going on in the minds of the Vikings in Galloway all those years ago. They tell us about the sensibilities of the time, reveal displays of regal rivalries, and some of the objects even betray an underlying sense of humour, which the Vikings aren’t always renowned for!” he added.
Stuart Campbell of the Treasure Trove Unit, said there was further research to be done on the items.
“The complexity of the material in the hoard raises more questions than it answers, and like all the best archaeology, this find doesn’t give any easy answers,” he said.
A large glass bead, found among the other riches. Image credits Santiago Arribas Pena.
“Questions about the motivations and cultural identity of the individuals who buried it will occupy scholars and researchers for years to come.”
The artifacts are now in the care of the Treasure Trove Unit, who are assessing its value on behalf of the QLTR. After this, the hoard will be offered to Scottish museums and the finder will be eligible for the market value of the items — a cost that the museums will cover.
This beautifully crafted artefact might just be the crown jewel of the hoard. Image via Santiago Arribas Pena.
However, it’s been estimated that this might amount up to £1m in order to do so — a hefty price-tag for any museum.
The hoard’s discovery is also set to feature on the 24th of March in BBC’s latest episode of Digging for Britain hosted by Dr Alice Roberts.
Since man first found he could sharpen a stick to defend himself, we’ve realized the importance of good quality tools in making our life easier and more bountiful. In our search for better and better tools and weapons, wood gave way to rocks tied to sticks, that were in turn replaced by chiseled pieces glued and fastened to hardy handles. Whole communities came to rely on those that could turn their hand to working stone, to people such as Otzi.
Otzi was the finest stone-shaper in the village; the tools he produced bit deep into soil, fell trees and boars alike with ease, and chased away many a pillaging group. They were the zenith of the day’s technology, underpinning every field of human activity, from agriculture to crafts, to battle. And today, grasping an axe that he himself chiseled, standing next to his fellow villagers, facing strange people from stranger lands, Otzi was prepared to defend his home once again. But as battle raged and stone splintered on the invader’s weird, reddish weapons and armor, realization crept over the defenders; stone was no longer king.
Copper is widely believed to be the second metal (after gold) that humans learned to shape and utilize. It was more easily encountered and obtained than other metals as it forms native element bodies throughout the crust, and archaeological consensus places its discovery at 9000 BC somewhere in the Middle East — though like agriculture, it was most likely discovered independently by several groups of people.
A lot softer than iron, with 3.0 on the Mohs scale compared to iron’s 4.5, and very malleable, the metal could easily be beaten into shape and if done at room temperature this would create more durable edges as the metal’s crystals aligned to the mechanical stress. Being easy (compared with other metals) to mine and process but more durable, malleable and less brittle than stone, copper started replacing it as the material of choice for tools, weapons and other objects. However, as limited people had knowledge of the metal or how to work it and as it was fairly expensive, stone remained the most used material throughout the copper age.
Still, this was little comfort to the peoples that were enslaved by more technologically advanced tribes and empires, in part due to lacking the adequate weapons to defend themselves, such as our hypothetical Otzi.
From finding to extracting
Elemental copper was the first source of the metal that humans used, for obvious reasons — it’s easy to find and doesn’t need much refining. If a big enough chunk was found, all you had to do was hammer it into whatever shape you needed.
Native copper. Image via wikimedia
However, this is limited by the size and shape of the nuggets miners were able to find, and there wasn’t any way of making sure there weren’t impurities in the metal mass, that could ruin the final object’s properties. As copper deposits were exploited over time, such pieces of metal were increasingly hard to come by, so craftsmen started melting together smaller bits of copper into bars that they would then turn into finished products.
Most copper nuggets are found in this size. Image via images-of-elements
Experimenting with melting the metal, smiths learned that they could treat copper to have different properties, depending on what they would use it for. If you took a copper bar, heat it up and let it cool down slowly (a process known as annealing), the metal’s crystalline structure would arrange in a more homogeneous structure and the copper was much softer and easier to shape, good for jewelry or coinage.
On the other hand, cold-processed copper had a more arranged crystalline structure, harder than the annealed metal. Tools and weapons were shaped this way, to make them more durable and allow them to keep a better edge.
Top: Annealed steel alloy. Bottom: tempered steel. While steel is an alloy, copper crystals behave similarly to heat treatment, with cold-shaped pieces showing the same internal stresses between crystals, helping them hold each other in place. Image via wikipedia
After deposits were depleted of most native copper bodies, smelting was employed to extract the metal from its ores. Early smelters were very primitive, so in these early days of metallurgy, only the most worthwhile material was processed. For example, some of the first recorded smelters were employed by the Sumerians, and they were no more than shallow pits in which ore was thrown over burning charcoal.
Exactly how they reached sufficiently high temperatures in the absence of bellows is still a matter of speculation — one theory holds that the smelters were covered with clay, leaving only an opening towards the prevailing wind to feed the fire. Hieroglyphs show that the Egyptians also had this problem, but solved it using a long tube to blow air into the furnace.
“I swear Amun, this job blows!” Image via tf.uni-kiel
This is another major turning point in our history that copper brought about. Smelting involves much more than just melting the metal from the rock — it’s a delicate chemical process, requiring the use of a reducing agent to scrub the metal atoms of oxidizers (most often carbon in the form of charcoal that releases carbon monoxide as it burns, then pulls oxygen atoms from the ore, forming CO2) that usually bind to them, and flux is used to purify the melt.
Smelting was probably developed over a long period of time, with small improvements being added over time to the procedure. But without a metal useful enough to impose itself in human society, that could be found both in native and ore forms, smelting might have never been developed. And without smelting, other metals such as iron or aluminum would have never been discovered and used.
In the later part of the Copper age, as technology advanced, casting was employed on a wider and wider scale as a production method, especially for works of art such as statues or jewelry, for religious objects and some tools. This process required skilled craftsmen, as it is quite difficult to do with copper because of the formation of gas bubbles during the pouring of the metal and its shrinking when it cooled down.
The social impact
Ok so now we have a pretty good idea of how copper was extracted and processed in the beginning, but how exactly did the discovery of metal (especially one durable and abundant enough to rival stone) impact the lives of people?
In a time where virtually all labor was muscle-driven, having access to a material that can make your tools bend a bit instead of breaking — but that’s ok because you can totally hammer it back up — or make your sword shatter an enemy’s weapon was like playing life with cheat codes. This is why we tend to create chronologies (Stone age, Iron age, etc.) based on how widespread the use of some such material was in a certain region.
During the early stages of an age the use of the new metal was still infrequent, but became widespread during the middle stage and common in the final period, and the impact on societies should be viewed with this in mind.
One of the most distinctive societies of prehistoric Cyprus (the island from which the name of copper is derived) was the Erimi Culture. Mainly fishers and farmers throughout the Paleolithic, during the Copper Age the Erimi experienced a huge population increase, an explosion of arts and crafts but most importantly — the creation of social hierarchies.
People loved it; they used it for everything, from nails to pans to roof tiles, statues of gods or demons or pretty young ladies (hopefully) — if they could afford it. Villages grew in size and were fortified, with large houses and high-status goods denoting differences in wealth and position. Grain storage and food preparation became private rather than communal, as it was in the earlier villages.
Reconstruction of an Erimi house. Image via wikipedia
With access to better tools, farmers — most of the population — were able to produce much more food than they required to feed themselves; those that had access to copper — few in number — would sell the tools, the weapons and miscellaneous metal goods that the community required, turning a sweet profit for themselves. Trade flourished both internally and with other peoples, and as the Erimi accumulated wealth, they had more and more time and resources to spend on arts, culture and science.
A typical copper ingot in the late Chalcolithic, meant for export. Image via wikipedia
This trend keeps around the globe — as groups discovered copper and the means to extract it, they experienced (with some exceptions) huge demographic, economic, and cultural explosions, with social layers or hierarchies being cemented during this period.
Copper leads to bronze
Sometime in the late Chalcolithic, someone figured out that if you melt copper together with another metal such as arsenic, it becomes harder, more resilient and altogether better at everything people used copper for up to them. Exactly how this was discovered is still a matter of debate, but since copper ores are naturally contaminated with other metal, such as arsenic and tin, it’s likely it was discovered by chance during smelting.
No matter how the alloy came to be, it quickly started replacing copper wherever it was available, just as metal once replaced stone. Most artifacts retrieved from the Bronze age are made up of a type of copper alloy called brass, a mixture of copper and zinc, known for its bright gold-like appearance.
Brass bar. Image via sino-cool
Although it lost its monopoly on human metal industry a long time ago, copper is still one of the most valuable and sought-after metals even today. Its resistance to corrosion, thermal and electrical conductivity, ductility and malleability make it irreplaceable in a wide range of industrial sectors, from plumbing to electronics.
Bars of bronze. Image via atlantishome
It’s so valuable to us that up to the 20th century, Sweden was known to have a “copper backed currency” — a mine in Falun, known as the Great Copper Mountain, operated from the 10th century to 1992, produced two thirds of Europe’s copper demand in the 17th century and helped fund many of Sweden’s wars during that time.
But no matter how useful it is, or how profitable it is to trade, in my opinion the real value of copper is that it thought us how to shape metal. It freed us from the constrains of wood, bone, fibers, stone and gave us the means and knowledge to produce tools and technologies powerful enough to shape the world around us.
Imagine a nugget of real, 20 carat gold floating merrily on the milk foam of your cup of warm cappuccino — scientists from ETH Zurich have found a way to do it. It’s not super-cappuccino, or diamond-strong foam — scientists led by Raffaele Mezzenga, Professor of Food and Soft Materials at ETH have produced a novel foam of gold, a three-dimensional material that is actually mostly…empty.
This 20 carats gold foam is lighter than milk foam. Image via ethz
“The so-called aerogel is a thousand times lighter than conventional gold alloys. It is lighter than water and almost as light as air,” says Mezzenga.
To the naked eye it looks just like a sturdy, shiny block of conventional gold, but that’s where the resemblance ends — this foamy gold (that’s what I’m calling it) is soft and malleable by hand. It’s 98 percent air held together loosely by gold (four-fifths of the solid material) and milk protein fibrils (one-fifth), qualifying it as 20 carat gold.
The material is created by first heating milk proteins until they coalesce into nanometre-fine fibres named amyloid fibrils. The fibrils are placed in a solution of gold salt, where they interlace into a basic structure that the gold crystallizes on in small particles. The end result is a gel-like gold fibre network.
“One of the big challenges was how to dry this fine network without destroying it,” explains Gustav Nyström, postdoc in Mezzenga’s group and first author of the study.
Air drying wasn’t viable as it could damage the gold structure, so the scientists opted for a gentler but more laborious process that relies on carbon dioxide, assisted by the Professor of Process Engineering Marco Mazzotti.
This method of production, where the metal particles crystallize during the manufacture of the protein scaffold rather than after its completion, is novel. And one of its biggest advantages is that it makes it easy to create a homogeneous gold aerogel that mimics gold alloys perfectly.
It also allows scientists numerous possibilities to influence the properties of the material.
“The optical properties of gold depend strongly on the size and shape of the gold particles,” says Nyström. “Therefore we can even change the colour of the material. When we change the reaction conditions in order that the gold doesn’t crystallise into microparticles but rather smaller nanoparticles, it results in a dark-red gold.”
A foam of amyloid protein filaments without gold (top), with gold microparticles (middle) and gold nanoparticles (below). Image via ethz
The new material could be used in many of the applications where gold is currently being used, says Mezzenga. The substance’s properties, including its lighter weight, smaller material requirement and porous structure, have their advantages. Applications in watches and jewellery are only one possibility.
Another use demonstrated by the scientists is chemical catalysis: since the highly porous material has a huge surface, chemical reactions that depend on the presence of gold can be run in a very efficient manner. The material could also be used in applications where light is absorbed or reflected. Finally, the scientists have also shown how it becomes possible to manufacture pressure sensors with it.
“At normal atmospheric pressure the individual gold particles in the material do not touch, and the gold aerogel does not conduct electricity,” explains Mezzenga. “But when the pressure is increased, the material gets compressed and the particles begin to touch, making the material conductive.”
A team of archaeologists working in Denmark have made a puzzling discovery: they found nearly 2,000 spectacular gold spirals dating from the Bronze age. The reason why they were made, especially in such a large number, is a mystery and the trove baffled scientists.
Bronze Age gold spirals found in Boeslund, 900-700 BC. Credit: Morten Petersen / Zealand Museum.
The spirals are made from pure gold, hammered down to just 0.1 millimeters thick, and measure up to 3 cm long; together, they weighed 2-300 grams. While archaeologists have no clear indication of what their purpose was, Flemming Kaul, a curator with the National Museum of Denmark, believes the coils were part of a Bronze Age ritual honoring the Sun god.
“The sun was one of the most sacred symbols in the Bronze Age and gold had a special magic,” Kaul writes. “Maybe the priest-king wore a gold ring on his wrist, and gold spirals on his cloak and his hat, where they during ritual sun ceremonies shone like the sun.” It’s also suggested the gold was simply buried as part of an elaborate sacrifice.
Gold spirals surrounded by flakes of birch pitch. Credit: Flemming Kaul / National Museum of Denmark.
Scientific analysis in the Museum’s lab found chunks of birch bark tar, a substance used by prehistoric people and Neanderthals as an all-purpose adhesive since 80,000 years ago. Archaeologists believe the spirals were placed inside a sort of jewelry box or chest before being buried in the Boeslunde field.
Interestingly, it wasn’t archaeologists that initially found the trove, but amateur metal detectorists Christian Albertsen and his uncle Hans Henrik Hansen. They also made several other discoveries in Boeslunde, on the Danish island of Zealand, including two extremely elaborate gold bowls which incredibly thin gold wire wound around their handles to look like dragons.
Credot:Morten Petersen / Museum Vestsjælland.
The Zealand Museum and the National Museum are continuing the diggings in the area, and in the meantime, the local museum in Skaelskor is holding a viewing event for two hours, along with a talk from a curator who will discuss the find. If you’re in the area, be sure not to miss it!
For thousands of years gold has been the embodiment of wealth. Its chemical stability and scarcity make it ideal for coinage. In the USA, the link between gold and currency has only been weakened in 1933 when the gold standard fell out of use, and was fully separated from the dollar in 1971. While currently no country uses the gold standard any longer, money deriving its value from government regulation or law (called fiat currency), for much of human history gold has been the basis of most economic structures: everything had a corresponding value relative to the metal.
It is found in economy as a carrier of value, in art as a symbol of grandeur and in social interactions as a sign of high status. Religions across the globe reinforce this key place for gold, using it either literally – in contexts linked with divinity – or metaphorically, as mark of purity. But for the central role it played in human society, we know surprisingly little about how gold came into being. Research by the Harvard-Smithsonian Center for Astrophysics (CfA) may help us better understand the processes which create this soft, shiny and precious metal.
Gold rules the world. Powerful dark magic helps too. Image credit to vincentxyooj, via: deviantart.com
While we’ve previously wrote on the importance and creation of gold here, research based on recent observations of a nearby gamma-ray burst, GRB 130603B, helps to explain how gold and silver atoms are created.
These bursts are flashes of high-energy light (gamma rays), associated with explosions. Researchers believe that the immense energy released in the GRB 130603B event resulted from the collision of two neutron stars–deceased cores of stars that have exhausted their fuel and exploded. Gamma-ray bursts come in two varieties – long and short – depending on how long the flash of gamma rays lasts. GRB 130603B, detected by NASA’s Swift satellite on June 3rd, lasted for less than two-tenths of a second, followed by a glow dominated by infrared light that radiated from the area for several days after the explosion, exhibiting unusual behavior.
Its brightness and behavior didn’t match a typical ‘afterglow,’ which is created when a high-speed jet of particles slams into the surrounding environment. Instead, the glow behaved like it came from exotic radioactive elements. The neutron-rich material ejected by colliding neutron stars can generate such elements, which then undergo radioactive decay, emitting a glow that’s dominated by infrared light – exactly what the team observed.
“We’ve been looking for a ‘smoking gun’ to link a short gamma-ray burst with a neutron star collision. The radioactive glow from GRB 130603B may be that smoking gun,” explains Wen-fai Fong, a graduate student at the CfA and a co-author of the paper.
In this high-energy event, two neutron stars collide. Scientists believe the glowing aftermath is the origin of elements such as gold. Image via: popsci.com
The team believes that significant quantities of gold and other heavy elements were created and released in that area during the collision.
“We estimate that the amount of gold produced and ejected during the merger of the two neutron stars may be as large as 10 moon masses–quite a lot of bling!” lead author Edo Berger said in a statement.
“To paraphrase Carl Sagan, we are all star stuff, and our jewelry is colliding-star stuff,” says Berger.
As gamma-ray burst events are quite frequent, Berger and his colleagues hypothesize that all the gold in our universe could have been created this way.
The team’s results have been submitted for publication in The Astrophysical Journal Letters and are available online. Berger’s co-authors are Wen-fai Fong and Ryan Chornock, both of the CfA.
At a recent meeting of the of the American Chemical Society, researchers proposed a novel source of valuable metals: waste water. They proposed a method that could be used to extract valuable metals like gold, silver or titanium which end up in waste water plants via the city’s sewage.
Who the heck throws gold down the toilet, you might ask. Well, you’ve done it plenty of times without knowing it, most likely.
“There are metals everywhere,” Kathleen Smith of the U.S. Geological Survey (USGS) says, noting they are “in your hair care products, detergents, even nanoparticles that are put in socks to prevent bad odors.” Whatever their origin, the wastes containing these metals all end up being funneled through wastewater treatment plants, where she says many metals end up in the leftover solid waste.
According to Smith, more than 7 million tons of biosolids come out of U.S. wastewater facilities each year. Half of that is used as fertilizer, while the rest is sent to landfills or is incinerated. One man’s trash, is another’s treasure, and with this in mind Smith and colleagues are currently working on ways to value solid waste, particularly rare metals. At first glance, you might think this isn’t worth it, considering the energy (money) you need to pump in the system to extract, but the waste from 1 million Americans might contain metal worth $13 million. In some places, the concentration of gold is about the same or more than that found in natural mine deposits currently being exploited.
This image shows microscopic gold-rich and lead-rich particles in a municipal biosolids sample. Image credit: Heather Lowers, USGS Denver Microbeam Laboratory
To extract metals, the researchers propose methods commonly in use by the mining industry. This involves using chemicals called leachates, which this industry uses to pull metals out of rock. Typically, these are very harmful to the environment, but at the American Chemical Society meeting, the researchers claim that these can be contained to waste water plants only, with no adverse effects to the environment or the population.
So far, Smith’s group has collected samples from small towns in the Rocky Mountains, rural communities and big cities. They found traces of platinum, silver and gold, and on a case by case basis, these could be found in a high enough concentration for extraction to become economically feasible.
British researchers have demonstrated three ways gold nanotubes can be used against cancer: 1) high resolution in-vivo imaging; 2) drug delivery vehicles; 3) agents that destroy cancer itself. Their work shouldn’t be viewed as yet “another” hack that seeks to eradicate cancer. We need to be more realistic than this. Instead, the findings have the potential to be a great measure that both diagnoses and treats cancer at the same time, complementing conventional surgery and, hopefully, avoiding the need for chemotherapy.
Pulsed near infrared light (shown in red) is shone onto a tumor (shown in white) that is encased in blood vessels. The tumor is imaged by multispectral optoacoustic tomography via the ultrasound emission (shown in blue) from the gold nanotubes. (credit: Jing Claussen/iThera Medical, Germany)
Gold nanotube schematic showing hollow interior (left) and transmission electron microscope image (right) (credit: Jeremy Freear/Advanced Functional Materials)
The scientists at the University of Leeds made the first successful demonstration of the biomedical use of gold nanotubes in a mouse model of human cancer. They injected the gold nanotubes intravenously then shone a pulsed infrared laser beam. By adjusting the brightness of the laser pulse, the researchers were able to control whether the gold nanotubes were in imaging mode or cancer-destruction mode. In addition, beforehand, the researchers claim the nanotubes can have their lengths adjusted in order to absorb a precise wavelength.
In image-mode, the gold nanotubes absorbed the the energy from the laser pulse and generated ultrasound. Using multispectral optoacoustic tomography (MSOT), researchers then read the ultrasound waves and detected the gold nanotubes.
For cancer destruction, there were two options:
Use a stronger laser beam to rapidly raise the temperature in the vicinity of the nanotubes so that the temperature was high enough to destroy cancer cells.
Load the central hollow core of the nanotubes with a therapeutic payload.
Although gold is not particularly harmful to the body (unless you pass a certain threshold), the team coated the nanotubes with a protective sodium polystyrenesulfonate (PSS) coating. Ultimately, the nanotubes are safely excreted from the body, after they meet their purpose.
“High recurrence rates of tumors after surgical removal remain a formidable challenge in cancer therapy. Gold nanotubes have the potential to enhance the efficacy of these conventional treatments by integrating diagnosis and therapy in one single system,” said lead author Sunjie Ye, who is based in the School of Physics and Astronomy and the Leeds Institute for Biomedical and Clinical Sciences at the University of Leeds.