Magical and Essential: On the Mineral and Metallic Bases of Our World

Featured image: Francesco Mocellin via Wikimedia Commons

Nestling alongside strange lunar plains, bright red lakes, mountains of salt and fuming volcanoes, the Salar de Atacama is a place of rare, discomforting beauty. On its fringes are flamingos, guanacos and vicuñas, the wild cousins of the llama and alpaca. But as you journey inwards, towards what scientists call its nucleus, life begins to disappear. Here, within a barren desert is an even more barren expanse.

This is the driest place on earth, save for some benighted parts of Antarctica. You notice it the minute you arrive: you feel it on your skin, in your throat and on your cracked lips. In my time there the humidity did not exceed 12 per cent, which is perfect for a Finnish sauna but less ideal for biological life.

The technical explanation is that this desert of sand, stone and salt sits in what is termed a two- sided rain shadow. To its east is the Andes; to its west is the Chilean coastal range of mountains. The upshot is that rain is very, very rare. There are some weather stations that have never recorded a single drop, though in some parts, including the Salar, there are very occasional torrential showers. Locals call them the Bolivian winter, though paradoxically they usually fall in the summer.

The Salar itself is a salt lake, though it doesn’t look much like the kind of salt lakes you might have in your mind’s eye: those massive, flat expanses of white like the Great Salt Lake of Utah or the Salar de Uyuni in Bolivia. The Salar de Atacama is, by contrast, brown and slightly scaly. The brown color is in fact a very thin coating of sand, which has blown out from the neighboring desert on to the surface here and clings to the salt. The scaliness is a function of the fact that the salty surface is still slowly, imperceptibly growing, with new stalks of salt reaching like fingers towards the sky. Other salt lakes are white and flat because the rain tends to wash away the sand and dissolve the scaly claws before they can form. But since it doesn’t really rain here, the fingers and crust slowly carry on growing.

No other element has quite the same combination of lightness, conductivity and electrochemical power.

At one point I strode out on to this crispy surface and soon realized I’d made a mistake. You are supposed to wear tough gloves if you go near the unbroken salt, since those fingers and edges are sharper than a chef’s knife. The surface is so uneven and unpredictable that it is hard to pick your way through without occasionally stumbling, and if you stumble and use your hands to break your fall…after five minutes of unsteadily picking my way through the thicket of salt I paused, looked down at my fingers, visualized what they’d look like if I fell and turned back. With each new stride the salt crackled and snapped at my feet. Strange echoes twanged through the surface like the thawing ice on a Nordic lake. These sounds were all the more spooky because of what I knew lay a few meters beneath the surface: an utterly gigantic underground reservoir of concentrated saltwater. This saltwater, this brine, is the business; it’s what we are here for. It is a deep, rich solution of many different salts of sodium, magnesium, potassium, boron and, yes, lithium.

There is a certain empirical logic that secures lithium’s place as one of the six key members of the Material World. This is a magical metal: alongside hydrogen and helium it was one of the three primordial elements created in the Big Bang, making it one of the oldest pieces of matter in the universe. No other element has quite the same combination of lightness, conductivity and electrochemical power. No other metal is quite as good at storing energy. So light it floats in oil, so soft you could cut it with a kitchen knife but so reactive that it fizzes and bangs when it makes contact with water and air, it is one of those materials you don’t ever see in its elemental form outside of a chemistry lab. And this reactivity helps explain why lithium is at the heart of the most powerful batteries, and therefore the heart of the twenty-first-century world.

If we are to eliminate carbon emissions and phase out fossil fuels in the coming decades we will have to electrify much of the world (less oil but more copper). We will need to build many more wind turbines (steel, silica and copper) and solar panels (copper and metallurgical silicon), not to mention hydroelectric dams (concrete). But none of this will do the trick unless we have a way of storing that energy. We will need to store it for short periods to deal with the inherent intermittency of renewable sources of energy, such as the sun and the wind. And we will need to store it so that road vehicles can get from A to B without burning fossil fuels.

While batteries do not provide all of the answers, they are a large part of that missing link that might just get us there. And while there are many other chemicals inside batteries—of which, more later—there is no beating lithium when it comes to its lightness and its ability to store energy. As science writer Seth Fletcher puts it, “The universe hasn’t given us anything better.”

The reason we are back in Chile once again is that in much the same way as there is nowhere else on the planet with quite so much copper, there is also nowhere else on the planet where we can lay our hands on quite so much lithium. The Salar de Atacama is the single biggest source of lithium anywhere.

Quite how it came to be here is one of those mysteries we are only beginning to fathom, but as things currently stand, the most compelling explanation is as follows. Think of the Salar as a kind of cauldron, with the Andean volcanoes on one side and another smaller set of hills on the other. Water comes down from the Andes in a number of different rivers, which run down through deep gorges—quebradas—towards the basin. Along the way this water picks up microscopic amounts of those unusual minerals in the Chilean earth, but when it hits the bottom of the valley it has nowhere to go. Trapped inside the cauldron, the water percolates into the gravelly ground, where—this being one of the driest regions on earth—much of it evaporates.

Only when you imagine this process happening over millions of years of deep time—the river water with its tiny quantities of leached volcanic minerals coursing into the basin, soaking through the alluvial fan and then evaporating under the punishing South American sun—do you start to comprehend how this enormous salt lake came to be. Millennium after millennium the water evaporated, leaving that concentrated liquid cocktail of salts. Millennium after millennium the sodium chloride, which precipitates faster than the other ingredients in this brine, formed into a crust on the surface: that crust I briefly stumbled over. In the oldest sections furthest from the rivers, the salt folded into an entire mountain range, the Cordillera de la Sal, as the tectonic plates beneath this landscape continued to crunch together. The process is probably still happening today, but too slowly to be in any way discernible.

And there you have it. The Salar is undoubtedly striking to behold, but what is more mind-boggling is what lies beneath it. In parts, the salt is at least 3 miles thick. In parts there is only a thin skin and beneath it vast quantities of ancient brine, which has sat beneath the surface, soaking underground like a sponge, for at least 3 million years. We tend to think of water as being constantly in motion, whether in the sea or our rivers or in the droplets that evaporate from lakes into clouds which rain down and complete the cycle. But the water here has been imprisoned in this dark, salty dungeon—still and inert—since well before the dawn of humanity.

That the batteries in mobile phones, laptops and electric cars are made in part from this ancient liquid is another one of those paradoxes you are already familiar with from the Material World: the very old giving birth to the very new. But there is nonetheless something dizzying about it. As you watch the briny water gushing out of the pipes here it is hard to get your head around the fact that this is the first time it has seen the light for millions of years. Or that it will soon be entombed again inside a battery in a contraption on the other side of the world.

Two companies mine the lithium in the brine. There is Albemarle, which started out as a paper manufacturer and chemicals firm before doubling down on lithium as well, and SQM, that same chemicals company we encountered back in the salt section, which mines caliche and turns it into fertilizers elsewhere in the Atacama.

There is no beating lithium when it comes to its lightness and its ability to store energy.

The way this type of lithium mining works is relatively simple. The ancient brine is pumped out from under the salt crust, from brine wells located all over the Salar. It is channelled into gigantic ponds where the water is evaporated away. It is a slow process taking many months: first the sodium chloride precipitates, then the remaining brine is channelled into another big pond where the potassium salts precipitate, then into another evaporation pond where the magnesium salts are removed. Eventually, after well over a year, that brine that left the underground reservoir as a pale blue liquid has been concentrated into a yellow-green solution, almost as bright as a neon highlighter. At this stage, it is about 25 per cent lithium chloride, though the green color actually comes from the boron still left in the solution.

You might have noticed that not only is this process rather straightforward, it’s also precisely the same technique the Phoenicians used when making salt in Ibiza thousands of years ago and artisan producers still use today to turn seawater into fleur de sel. Only here, alongside the sodium chloride is lithium salt: lithium chloride. Really, the main difference is its scale: the evaporation ponds turning out Mediterranean salt are measured in meters whereas the ones here in the Salar are measured in kilometers.

SQM, which these days extracts most of the lithium, became one of the world’s biggest lithium producers almost by accident. It originally started pumping out brine from the Salar in the 1990s not so much to produce lithium as to produce potassium: potash. The lithium was an interesting by-product. Indeed, up until recently, no one paid all that much attention to this element, which unlike the other materials in this book played little more than a passing role in civilization.

Perhaps its most important use was as a pharmaceutical: lithium became such a popular treatment for bipolar disorder and depression that it entered the cultural lexicon, featuring in songs by Evanescence and Nirvana. Indeed, it is so effective at subtly altering one’s mood that some have argued it should be added to drinking water in much the same way as many countries add fluoride to help dental health. It has a small but all-important role in new nuclear power technologies. Lithium turns out to be an essential coolant for molten salt reactors and is the main way of breeding the tritium we will need if we ever get round to achieving mainstream nuclear fusion. There are a few other uses: it can help strengthen glass (lithium being one of the first elements Otto Schott added to his melts in the nineteenth century). It plays a role as an alloy in certain metals and its slipperiness means lithium compounds make for excellent lubricants, as well as improving the look and wear of ceramics.

All of which makes lithium something of an outlier in the Material World. All of the other materials we have encountered thus far have been essential parts of our lives for generations if not centuries. But had this book been written a few decades ago lithium would likely not have made the shortlist at all. Its place as one of the essential substances in our lives is the fruit of a long-standing challenge, a little like the rediscovery of the recipe for cement or the invention of the solid state semiconductor. The quest to create a strong, powerful, resilient battery was a century in the making.


material world

Excerpted from Material World: The Six Raw Materials That Shape Modern Civilization by Ed Conway. Copyright © 2023. Available from Alfred A. Knopf, an imprint of Knopf Doubleday Publishing Group, a division of Penguin Random House, LLC.

Source link

About The Author

Scroll to Top