Nov 29, 2023

"Why would someone expend the effort, risk damaging the environment, and possibly harm themselves to refine metals from scrap?"

The life of a discarded smartphone does not end when its owner gets a shiny new replacement. Many people cast the old model aside, sending the bundle of metal, battery acid, and plastic to a landfill, while a small, conscientious percentage chooses to repurpose or recycle their old pal.

After dropping off a stash of old consumer electronics at a designated recycling venue, the electronics in close-to-working order are often refurbished and put back into use through retail sale outlets or donation. Those electronics that are in not-so-great condition are de-manufactured (disassembled) to obtain useful, quickly interchangeable components like RAM. Another option requiring far fewer computer experts exists, however, namely, the wholesale destruction of the electronics to obtain scrap metal. This process is often carried out in large warehouses where industrial shredders tear desktop towers and hard drives into inch-long strands of metal that will later be sold as wholesale scrap. Metals worth considerably more than the steel and aluminum shells of consumer electronics are present in these electronics. Gold, platinum, tantalum, and several other rare and valuable metals are used in small quantities in smartphones and computers, but the employee skill sets and time necessary to obtain and refine these metals often makes metal-specific recycling efforts cost prohibitive. A burgeoning group of North Americans and Europeans with spare time on their hands, however, are turning to at-home recycling efforts to obtain impressive quantities of gold from unwanted electronics.

* * *

The amateur scientists looking to recover gold and platinum from computer parts are not too different from the elderly men and women clad in socks and sandals who wander along beaches combing the sands with a small shovel and metal detector in hand. There is one major difference between these two groups of treasure seekers, however. Those performing at-home recycling and recovery from computer parts know where their treasure lies; it's just a matter of performing a series of chemical reactions to retrieve the desired precious metals. Gold is head and shoulders the most desired of the possible metals to refine through recycling due to its abundance in consumer electronics.

A number of companies sell precious metal recycling and refining kits on the Internet, with prices starting as low as seventy dollars, provided the amateur recycler already owns a supply of protective equipment and personally manages chemical waste disposal. More expensive kits make use of relatively safer electrolysis reactions--similar to the hair-removal method touted in pop-up kiosks at shopping malls. This slightly safer method brings with it a much higher price tag, with retail starter kits beginning in the $600 range before rising to several thousand dollars. This high price is the cost of doing business for someone with time and (literally) tons of discarded computer equipment to refine, but the cost of entry is a losing proposition for an individual with a few computer monitors in the attic.

Clipping the gold-containing connectors off and selling them directly to a wholesaler adds a middleman, but it eliminates exposure to dangerous acids and decreases the chance of your house blowing up. A pound of clipped and cleaned connectors can fetch as much as $75, while obsolete, gold-containing computer processors often sell for $1 apiece in bulk sales.

Let's be a little bold, however, and take a look at two hobbyists, and learn how they would skillfully recover precious metals from a pile of computer parts.


For amateur recyclers, the quantity of starting material is of utmost importance. The cost of the chemicals, the danger involved, and the time it takes to retrieve gold from discarded computer parts is substantial--one would never want to carry out a refining job on a few discarded office computers. Unless dozens, if not hundreds, of circuit boards and processors are at your disposal, it's really not worth the effort from a financial perspective, at least in First World countries. Without a large supply of material, one would be better off trying to strain the negligible pieces of gold in Goldschläger. The cinnamon-flavored liquor contains tiny bits of gold foil, with lore claiming the gold flakes decreased the amount of time between imbibing and intoxication. Using a flour sifter or an old T-shirt as a sieve, one can recover approximately one hundred milligrams of gold from a single bottle, all while being treated to a wild night of easy refining.

Two methods are available to the hobbyist seeking to recycle and recover gold from discarded circuit boards, computer processors, and other gold-containing scrap. In the first--what I will call the "scorched earth" method--the scrap is dissolved in one of the most concentrated acids known, and the gold is recovered through a series of steps that alter the properties of the acid solution and cause solid gold to form and fall out of the solution. The second method makes use of electrolysis and is considerably more elegant from a scientific standpoint but involves the nasty combination of acid and electricity.

To better illustrate these two methods, let's consider two urban gold prospectors--Ron and Anthony. Ron majored in chemistry in college, so he has a better theoretical understanding and a reasonable amount of money to acquire equipment. Anthony lacks an advanced science background, however, he isn't afraid to get his hands dirty, so danger and waste are not a big problem in his mind. Most of what Anthony learns is gleaned from back issues of popular science magazines, scouring websites, and personal trial and error.

Let's see how Ron would retrieve gold and other precious metals from computer scrap.

Before Ron begins his extraction process, he crushes and burns the computer parts in a metal drum or trashcan. This is not simply an opportunity for Ron to release some pent-up frustration through the destruction of office equipment; it is also a task that provides him with a reasonably homogenous mixture of gold-containing material. Ron then acquires sodium cyanide and dissolves crystals of the chemical in water. This is dangerous, but not as bad as direct cyanide exposure--such a dalliance will leave you with the taste of almonds in your mouth moments before falling into unconsciousness on the way toward cardiac arrest. Sodium cyanide, in the presence of water, bonds to particles of gold readily, forming a stable complex. Ron will use this property to separate the gold from the computer scrap and pull the gold away from sodium cyanide, leaving him with a very pure gold sample.

Once in solution, an electrical source--possibly a repurposed car battery--is connected to the container holding the sodium cyanide and computer parts. By directly applying an electric current, the gold, in time, will deposit onto the preselected portion of the electrolysis cell (often a steel rod). There are several dangers with Ron's approach--electricity and liquids are not the best of companions--but these dangers are easily overcome by someone with a light background in chemistry or engineering. Depending on the thickness of the gold-plated rod, Ron can scrape or dissolve the metal and start the electrolysis process over again.

Before we move on to Anthony's recycling efforts, let's take a moment and ask a vital question: Why would someone expend the effort, risk damaging the environment, and possibly harm themselves in order to refine metals from scrap? A portion of the draw to hobbyist recyclers could stem from popular fears of impending global disasters and the ensuing financial implications. Gold is sought as a hedge against tenuous economic climates due to its historic significance, but not everyone has the resources to purchase gold coins or gold by the ounce. Many (including Ron and Anthony) do have spare time, and thanks to the Internet a broad range of information is available to individuals looking to recover gold from everyday, obsolete objects.

In Anthony's "scorched earth" method, he dissolves electronics scrap he believes contains gold in aqua regia (the name derives from the Latin for "king's water," a historic name given to the mixture because it can dissolve gold and platinum, the so-called "royal" metals). Should anyone partake of aqua regia, he or she would surely destroy their esophagus and wreak havoc on their digestive tract, if the unlucky test subject survives.

Aqua regia is a mixture of two strong acids--hydrochloric acid and nitric acid--that can do plenty of damage on their own should they be spilled in the best of conditions, let alone in a makeshift home laboratory. Many of the precious metals, including gold, platinum, iridium, osmium, and tantalum, are highly unreactive metals, and a single strong acid is unable to break them down. Mixing nitric and hydrochloric acid, however, results in a combination by which gold and platinum can be dissolved, lost (but only for a short period of time), and eventually recovered by the hobbyist with a few more steps. It is not an increase in acidity that allows aqua regia to dissolve gold and platinum but rather a chemical interaction made possible by the two acids working together. Nitric acid alters gold atoms into a form that will readily bind to free atoms of chlorine, and a phenomenal amount of chlorine becomes available when gold is dissolved in aqua regia due to the presence of hydrochloric acid. Gold then exists in aqua regia as a stable gold-chloride complex with an indefinite shelf-life. George de Hevesy, a Hungarian chemist working in Denmark during World War II, made use of this interesting phenomenon to prevent Nazis from acquiring the Nobel Prize medals of German physicists Max von Laue and James Franck. Dr. de Hevesy dissolved the two medals in aqua regia and left the innocuous container on the shelf of his laboratory for over a decade, until he reversed the reaction and sent the gold to the Royal Swedish Academy of Sciences in Stockholm to recast the awards.

So far, all Anthony has done is toss a cadre of computer parts lined with millimeter-thin sheets of gold into the tenacious acid. Anthony uses better judgment and does not do what some minor league scientists with a death wish do at this step--heating the acid mixture to upward of one hundred degrees Celsius in order to decrease the dissolving time. Remind yourself, this is all taking place, in the case of a hobbyist, within a garage, apartment, or makeshift outdoor laboratory.

While aqua regia eats away at the plastic and metal in the electronics scrap, a number of toxic fumes are released. Anthony had better be wearing a respirator or performing this reaction in a fume hood and clad in acid-resistant coat and gloves. He should be wearing a rugged pair of shoes as well since sneaker bottoms take on the consistency of used gum when you step in a puddle of hydrochloric acid. Once the mixture is dissolved, Anthony makes the use of the best in over-the-counter protective equipment (hopefully remembering that pair of gloves) to remove the partially dissolved electronics from the vat of nitric and hydrochloric acid.

He then washes the partially dissolved parts off in water, collecting any small pieces that fall off and placing them back in the aqua regia. So far, Anthony has manufactured two very nasty sources of waste--a vat of aqua regia and the remaining water, which is now considerably more acidic than normal and contains a variety of random metals, including the lead and tin from dissolved solder, the "metallic" glue that keeps computer parts together. Never has recycling posed such a threat to the environment.

At the moment, any gold or other recoverable precious metal is lost forever within highly corrosive acid unless steps are carried out to reverse the process.

Anthony's gold (and possibly platinum, depending on the raw materials used) doesn't look much like gold anymore. In fact, the solution doesn't look like anything worth keeping. No visible pieces of solid gold are present, and the aqua regia/scrap mixture has changed from the clear, yellow-red color of aqua regia to a dirty-looking opaque green. Anthony shouldn't be discouraged, because his treasure is near: he just needs to perform some chemical magic.

At this point, he adds a chemical to selectively precipitate the metal he is looking to collect. He chooses an extremely inexpensive powder, sodium metabisulfite, since he is primarily looking to retrieve gold. Use of sodium metabisulfite is dangerous; this benign-looking white powder can set off asthma attacks or severe allergic reactions in a percentage of the population. Slowly adding sodium metabisulfite to the aqua regia mixture while stirring the liquid is much, much safer than the hypoallergenic alternative. If Anthony has a death wish, he could choose to slowly bubble the extremely toxic gas sulfur dioxide into the solution to reveal solid gold and leave him with an increasingly clear aqua regia mixture. Let's nix that idea, on the grounds of safety and insufficient expertise on Anthony's part.

After adding sodium metabisulfite, Anthony waits and hopes to see solid particles of gold--particles now the size of a grain of sand--begin to form in the solution. The gold still doesn't share the appearance of normal gold yet--the metal is presently a brown, mud-like slurry, one that needs to be removed from the aqua regia solution. Ideally, removal happens only after the aqua regia has been neutralized (either chemically or by digesting enough scrap material), with the brown gold being filtered out.

Once the gold-infused mud mixture is filtered, Anthony can use a solution of stannous chloride to find out if all the precious metals are precipitated out of the solution. Once all the gold is removed from the solution, Anthony then begins to clean the brown, sandy-looking gold. The gold is cleaned by washings with ammonia (more waste) and water (possibly more waste), and the gold still retains its brown, sandy disposition, but we are getting closer. Ideally, washing will remove the remaining impurities, allowing Anthony to obtain a purer final product.

Anthony cannot rest yet, although the gold is stable enough that he can take a break and grab a beer. To account for any excess water absorbed by the gold pieces in the washing process, Anthony kicks up the temperature on a hot plate and carefully heats the brown solid. While the hot plate step serves to dry the brown gold, Anthony will still need to perform a final, insane step to see the yellow shine of this most desired precious metal.

* * *

Now for Anthony's "intentional" fun time with fire and, ideally, a payoff for his effort, risk of life, and the cost of purchasing a variety of deadly chemicals. The now-dry sands of gold are wrapped in a cloth or old T-shirt and soaked in alcohol. An off-the-shelf liquor might work, as long as the proof is high enough, but reagent-grade ethanol from a chemical-supply company would work a lot better. In the final glorious step, Anthony lights the alcohol-soaked gold ablaze with an off-the-shelf blowtorch from a home repair store.


As the solid melts, the contaminants (including the cloth and alcohol) burn off and exit in a variety of gaseous forms. What remains is the shiny luster of gold--a sample up to 99.5 percent pure--in molten form. At this point, Anthony can let his recovered gold solidify as jagged rocks on his desk, or he can pour it off into a heat-resistant container and create homemade gold ingots.

Anthony's "scorched-earth" method creates a large amount of waste, is labor-intensive, and even when presented in this neutered form (a hearty farewell to the possibility of sulfur dioxide gas exposure), the process is pretty dangerous. Additionally, the protective equipment necessary to safely carry out an ongoing in-house refinery shares many of the signs that warn concerned neighbors of a home methamphetamine lab. Anthony is now a pariah in his neighborhood, but he does have some gold to show for his efforts. Now that we've looked at two popular methods used by basement recyclers to recover gold, let's ask a vital question--how do the amateurs handle the lingering problem of their efforts, carefully disposing of liters of toxic waste and leftover aqua regia? Industrial chemical manufacturers and academic researchers are held to stringent guidelines when it comes to caring for and eventually disposing of harmful chemicals through a "cradle-to-grave" initiative. An at-home operation does not necessarily receive regular inspections, but improper waste disposal (i.e., pouring waste into the sewer or a waterway) can result in jail time and enormous fines.

In the European Union, basement refineries walk the line of legality due to the 2003 Waste Electrical and Electronic Equipment Directive, which classifies almost all electronic waste as hazardous and mandates the separation of no-longer-wanted consumer electronics from the normal household waste stream.

Improperly disposing of toxic waste is a felony in the United States, but you have to be caught first. If you are cited, the Environmental Protection Agency can level fines in the tens of thousands of dollars; however, the fines rarely cover the cost of proper hazardous-waste disposal or of creating an infrastructure to repair damage to the environment. In light of the EPA's nationwide jurisdiction, the enforcement of pollution and recycling often falls to the state governments. The proactive government of California adds a small, upfront surcharge to the purchase of any electronic device with a screen to pay for the device's end-of-life recycling and to raise funds to buffer the environmental impact should the user toss the smartphone or laptop in the trash at the end of its life cycle.

Efforts to offset the environmental impact of short-lifespan consumer electronics are dwarfed by the growing consumption of the same devices in China, Pakistan, and India as these regions modernize. It's a numbers game--the developing regions of the world contain the majority of the world's population, a population every bit as interested in conspicuous consumption as the much-maligned citizens of North America and Europe have been over the past half century.


While the "scorched-earth" hobbyist approaches used by Ron and Anthony are dangerous, the Third World equivalent is disturbingly post-apocalyptic. Venturing into mountains of discarded monitors, desktop towers, and refrigerators, children and teenagers fight over sun-and-rain-exposed electronic parts in search of any metals--even ones the First World discards with every can of soda--for possible resale.

The disproportionate value of a dollar in world trade makes these battles worthwhile, and gives reason to collect copper, aluminum, and scrap steel that First World hobbyists often toss aside in their search for precious metals. A mere two-dollar profit margin on twelve hours' work is not worth the effort in the First World, but this tiny sum is the difference between a tenuous hold on life and starvation for the young workers who flock to these small dumps, ignoring the long-term health risks. Along with any possible precious metals, the young prospectors harvest the copper wire that runs through a computer and crisscrosses circuit boards, the aluminum on the degaussing coils of tube televisions and monitors, as well as copper-containing condensers from refrigerators.

Electronic waste collected for recycling with the best of intentions often goes astray with items earmarked for recycling circuitously finding homes in Third World landfills. In many situations, the collecting organization has little-to-no ability to influence how the donated materials are handled after they are passed on to a third party. From this arises a number of problems since it is typically twice as expensive to refurbish or safely recycle the electronic refuse as it is to transport electronic waste designated for recycling to the shores of another country.

Dumping practices have sprinkled garbage ports of call across the world--Accra in Ghana and the village of Guiyu in China are two prime examples. These ports have also appeared in the Philippines, Vietnam, and India, preying on coastal towns where individuals are in desperate need of income.

Once electronic waste is deposited in the landfills of poor villages, the waste will not stay there for long. Locals in Accra and numerous small towns spread across India and China learned of the possibilities for parts from abandoned computer monitors, televisions, and towers and, like the hobbyists mentioned earlier, took up efforts to retrieve the precious components. In a society where economic prosperity and annual average incomes are measured in the hundreds and not tens of thousands of dollars, the few dollars one might make during a twelve-hour foray through massive piles of rubbish is well worth the effort and risk.

The electronics wastelands littered throughout developing countries could not exist, however, without complicit partners in the destination countries. How do these relationships begin?


The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal was created in 1989 and signed by over one hundred and seventy countries in the intervening years, with the goal of preventing the transport of hazardous waste from developed countries to less-developed ones. At the center of the creation of the Basel Convention is a single ship with a hull full of hazardous waste: a cargo ship that illustrates the problems inherent when wealthy nations (and even local municipalities) turn to devious means to discard their waste.

An existing waste-disposal agreement allowed for incinerator waste from Philadelphia to be deposited in New Jersey, but the government of New Jersey began refusing the ash shipments in 1985. As incinerator ash continued to pile up in Philadelphia, the local government contracted the Amalgamated Shipping Corporation and the shipping vessel Khian Sea to carry the seven tons of waste ash to a privately owned, human-made island in the Bahamas.

The government of the Bahamas refused the Khian Sea's cargo, and, at the same time, the City of Philadelphia withheld payment of money due for waste disposal. This put those on the Khian Sea in a bind; the ship could not return to dock in the United States, leaving the crew to wander the Caribbean in search of a place to dump its ashen cargo.

The Khian Sea did eventually find a locale to leave some of its cargo: Haiti. Its crew deceptively described two tons of incinerator ash as fertilizer and successfully dumped a portion of the toxic cargo before the local government discerned the true nature of the deposit. The Khian Sea continued to look for a place to leave the remaining five tons of incinerator ash, going so far as to change the name of the ship several times in hopes of finding a taker as the crew journeyed to the Eastern Hemisphere. Unfortunately, the tale of the Khian Sea ends in mystery, with over ten thousand pounds of ash suspiciously disappearing during a 1988 journey from Singapore to Sri Lanka. Crew members likely dumped the five tons of ash into the Indian Ocean en route to a port in Sri Lanka.

As the story of the Khian Sea's journey spread, the United Nations motioned to draw up and ratify the Basel Convention. Although the convention is in place, it does not prohibit export of waste to less-developed countries. The treaty only requires consent on the part of the receiving country, ensuring that there is a willing caretaker at the port. Due to this loophole, the Basel Convention only acts as a sort of Golden Rule governing hazardous waste transfer. Willing caretakers abound, so the lure of setting up dumping sites at coastal villages continues to exist. All that is needed is for someone in a village, under the guise of a used-electronics entrepreneur, to accept a foreign shipment of waste electronics. He or she might earn a small sum of money for the act of acceptance and possibly recover some working electronics for themselves in the process. The rest can be dumped-- landfill space is often inexpensive, if not free, in these parts of the world. As we now know, many individuals are more than happy to go through piles of waste and loot the remaining useful metals and components.

Carrying out business in this manner is essentially a get-rich-quick scheme using a large amount of human capital, a financial undertaking setting up "toxic colonies" throughout the world, destroying not only the lives of the inhabitants but the very land on which the villages rest.


Those who choose to make a living by retrieving electronic waste from dumps, tearing the equipment down, and refining the rare metals found within them are exposed to many of the same hazards as our hypothetical hobbyists, but on a much higher scale. While inquisitive First World hobbyists like Anthony and Ron refine scrap for fun in their spare time, a recycler in the developing world performs the same work but for twelve to fourteen hours a day and with minimal protective equipment due to the prohibitive cost of respirators, gloves, and goggles. They carry out these activities in an even more dangerous environment as well, exposing themselves to the physical hazards of landfills before the first step of metal recovery begins.

Their tools are often crude. Workers place the metals in clay kilns or stone bowls and heat them over campfires. Heating the refuse loosens the solder present on many electronic parts-- solder that is typically made of lead and tin. Children huddle over the fire as the scraps are heated to the point where the solder is liquefied and a desired component can be pulled away for further processing.

The cathode-ray tubes in older computer monitors--an item not even contemplated for recovery by First World hobbyists because of the danger and minimal reward--are boons for profit-seeking recyclers in the developing world. Tube monitors contain large amounts of lead dust--as much as seven pounds of lead in some models--and at the end of these fragile tubes is a coveted coil of copper. While copper is not the most precious of metals, it is valuable due to its many applications, turning the acquisition of one of these intact copper coils into a windfall for a working recycler. Smashing a monitor to retrieve the coil often involves shattering the lead-filled cathode ray-tube, doing a phenomenal amount of environmental damage while covering the worker with millions of lead particulates.

What is done with the unwanted scrap after the useful parts are plucked out is another problem altogether. In many situations, unwanted pieces are gathered into a burn pile and turned to ash, emitting harmful pollutants into the atmosphere. What remains in solid form is often deposited in waterways--Mother Nature's trashcan--and coastal areas. There is rarely a municipal waste system in place to recover the unwanted scraps in these villages, and years of workers dumping broken and burnt leftovers into local streams has contaminated the soil and local water supply. Drinking water is already trucked into the recycling village of Guiyu from a nearby town due to an abundance of careless dumping. Cleaning the water system would likely be too costly and a losing battle if the landfill recyclers are unwilling to change their ways. The physiological impact of recycling electronic waste has been best studied among the inhabitants of China's Guiyu village. Academic studies show children in Guiyu to have elevated levels of lead in their blood, leading to a decrease in IQ along with an increase in urinary tract infections and a sixfold rise in miscarriages.

Many of the young workers flocking to the landfills feel compelled to sift through the electronic waste in order to provide for their elders under China's one-child policy, a policy placing an undo financial burden on the current generation. In addition to complications from lead exposure, hydrocarbons released into the air during the burning of waste have led to an uptick in chronic obstructive pulmonary disease and other respiratory problems, as well as permanent eye damage.

Fixing the long-term electronic waste problem in these villages is a complicated and costly proposition. Apart from a generation of children poisoned and possibly lost, this is a relatively new revenue source, with the oldest of the children involved just now entering their thirties. The area of Guiyu was once known for its rice production, but a decade of pollution stemming from electronic waste dumping and refining has rendered the area unfit for agriculture. The lack of a secondary income source in the area only results in a vicious cycle that funnels more young lives into dirty recycling.

Rejuvenating the soil and water sources after years of contamination would require efforts on par with the science fiction trope of terraforming. Numerous science fiction movies, television series, and novels--including Dune, Star Trek II: The Wrath of Khan, Doctor Who, and Firefly--use terraforming as a plot device to make otherwise uninhabitable planets lush and primed for habitation through technological hand waving. Real-life terraforming with current technology is far less ambitious and goes by a much less interesting name: soil remediation. Remediation calls for testing the soil, determining salvageable areas, and excavating the top several inches of contaminated soil and covering the ground with fertile soil brought in from another region. Turning over several inches of soil and replacing it with fresh, fertile soil is a reasonable and cost-effective option. As soil turnover begins to rejuvenate an area, additional steps can be taken to purify groundwater or seed the soil with nitrogen-producing "friendly" bacteria, with the nitrogen produced by the microbes used as a naturally replenishing in-ground fertilizer. Unfortunately, in areas poor enough to fall victim to electronic dumping, it is unlikely a government agency would step in to carry out soil remediation procedures.


Amid the human tragedies and environmental dangers of amateur recycling, there is an upside to scrap recovery. We may very well run out of usable geological deposits of these metals in the future--or, as we see from the ongoing Congolese conflicts mentioned in chapter 9, the deposits themselves could become too dangerous to mine through corporate means. Recycling rare metals from existing electronics scrap could become a viable option to match the current deluge of consumer electronics in a scarcity-driven world.

For example, tantalum is particularly coveted for its use in electronics. The metal is stable up to three hundred degrees Fahrenheit, a temperature well within the range of most industrial or commercial uses of the element. It works as an amazing capacitor, allowing for the size of hardware to become smaller--an evergreen trend in the world of consumer electronics. Tantalum is also useful for its acoustic properties, with filters made with the metal placed in smartphone handsets to increase audio clarity by reducing the number of extraneous frequencies. The metal can also be used to make armor-piercing projectiles.

A run-of-the-mill smartphone has a little over forty milligrams of tantalum--a piece roughly half the size of a steel BB gun pellet when one accounts for the variation in density between the metals. By itself, this is not a significant amount of tantalum, but a push to start harvesting tantalum and other high-demand, hard-to-find elements from discarded smartphones could create a large, semi-renewable resource of these scarce metals. The task of element-specific refining can succeed, as shown to a limited extent in the examples of Anthony and Ron's search for gold and platinum. Though the venture is cost- and work-intensive, such a process could provide a "last resort" should world reserves become depleted, and it could also offer an alternative to the horrors that have accompanied mining coltan and wolframite in conflict-stricken areas of the world.

Excerpted from "Rare: The High-Stakes Race to Satisfy Our Need for the Scarcest Metals on Earth" (Prometheus Books, 2015). Reprinted by permission of the publisher.