The digital world has something weightless about it: virtual worlds, fleeting images on social media channels, data, bits, and bytes. And yet, this digital experience has an entirely material foundation – not least the discourse around the energy consumption of AI data centers makes this material side of the digital visible. And taking a look at this is worthwhile.

I would like to introduce and recommend a book that has really excited me: “Material World” by Ed Conway. In it, the author explores the immense relevance of six raw materials for our modern civilization, largely an industrial and technological history. In his work “Material World,” he focuses on six essential substances without which our modern world would not exist: sand, iron, salt, oil, copper, and lithium.

Conway takes us on a fascinating tour of exploration. We travel to the hotspots of raw material extraction, to some of the most important mines in the world, but also to the processing sites, such as the gigantic silicon chip factories in Taiwan. The book impresses with a sweeping narrative style, does not require too much prior knowledge of chemistry and physics, and always places technical developments in their economic and historical context. For those interested: The book has around 500 pages, is published by Hoffmann & Campe, and costs 28 euros.

I would like to pick out two topics from the book below that play a crucial role, especially for our digital world: on the one hand, the production of silicon wafers based on high-purity quartz; on the other hand, the extraction of lithium, the raw material for our ubiquitous lithium-ion batteries.

Enjoy!

SILICON | SAND

In the first chapter, the author directly addresses a substance we all know: sand. When Conway talks about sand, he naturally first highlights its immense importance for the construction and glass industries. But he goes one crucial step further. Starting from the fact that sand basically consists of quartz – i.e., silicon dioxide – he dives deep into the world of silicon production.

This fascinating journey begins with the mining of high-purity quartz, more precisely in Spain, not far from the famous pilgrimage site of Santiago de Compostela. I will briefly quote from the book:

“Serrabal is a quartz mine. The layer of rock that has thrust the Pico Sacro and the surrounding smaller hills skyward is one of the purest quartz deposits to be found in the world. The white rock is highly coveted everywhere.”

But mining alone is not enough. For the complex further processing, the journey goes to Burghausen in Upper Bavaria, near the Austrian border, where the so-called Siemens process is used. This process, developed in the 1950s, is a technical masterpiece for producing polycrystalline silicon of extreme purity. Metallic silicon is first ground into powder and mixed with gaseous hydrogen chloride. At temperatures of over 1100 degrees Celsius, the material is distilled in a reactor and reassembled virtually at the atomic level. At the end of this process, thick layers of high-purity silicon grow on hot rods.

However, this process is extremely energy-intensive. To give you an idea: the production of high-purity silicon consumes about 3000 times as much energy as the production of cement and 1000 times more than the conversion of iron into steel. It is a demanding and costly process, but the result is spectacular: a substance that is purer than almost anything else on our planet.

The purity of this silicon is measured in so-called “nines.” For simple solar cells, silicon with eight nines – i.e., 99.999999 percent purity – is sufficient. The absolute peak, however, is semiconductor silicon for our computer chips. Here we are talking about up to eleven nines. This means: for every 10 billion pure silicon atoms, there is at most a single foreign atom! It is therefore hardly surprising that Conway gave this section the fitting heading “The Purest Substance in the World.”

For the next magical processing step, the journey takes us to the USA. The high-purity polycrystalline silicon must now be processed into so-called wafers – these are the wafer-thin slices on which the microchips are later created. This happens at the company Shin-Etsu, using the Czochralski process, named after the Polish chemist Jan Czochralski, who discovered the principle rather by chance in 1916. A tiny seed crystal is dipped into molten silicon and slowly pulled out under constant rotation so that a gigantic, perfectly structured single crystal grows.

To melt the silicon at these extreme temperatures, special crucibles are needed. And these crucibles cannot be made of just any material – they require the absolute purest quartz in the world. And fascinatingly, there is only one single place on our entire planet that supplies quartz of this required quality. Conway describes it like this:

“The crucibles in which the high-purity silicon is melted at Shin-Etsu before it is pulled into the ideal lump and then cut into wafers consist of a very specific form of quartz, and this is found in only one single place in the world. For a single location to control the global supply of a crucial material is rare and almost unheard of. But high-purity quartz – the type the crucibles must be made of, because otherwise no silicon wafers could be produced – must come from Spruce Pine, a small town in the Blue Ridge Mountains in North Carolina. For a long time, the mine – and thus the entire global supply of high-purity quartz – was operated by a single company, a secretive Belgian enterprise called Sibelco.” […] “Today there are two mines in Spruce Pine. Alongside Sibelco, the smaller Quartz Corp operates there, sending its mined stones to Norway for processing.”

The entire processing chain of silicon is a true parade of exclusive raw materials and amazing high technology. This extreme purity and cutting-edge technology are absolutely necessary, because the central building block of our digital age is built here in an unimaginably small space. Imagine: on a modern smartphone processor today, around 12 billion transistors are crowded together – and on an area smaller than a square centimeter!

A final example from the book perfectly illustrates this unfathomable precision. We are now at TSMC in Taiwan, one of the world’s largest chip manufacturers. Here, the tiny circuit diagrams are exposed onto the silicon wafers using extreme ultraviolet radiation. Since we are moving almost in the atomic realm here, the tools used must be absolutely flawless. A few lines from Ed Conway’s book on this:

“To direct the EUV light onto the wafer, Zeiss, as a supplier to ASML, produces so-called Bragg reflectors, special mirrors consisting of layers of silicon and molybdenum. Exactly how these mirrors are manufactured is, in turn, a closely guarded trade secret; according to one engineer, we must be content with the information that they consist of dozens of layers, are polished by robots, corrected on the outer layer with ion beams, and are presumably the smoothest human-made structures in the universe. If you were to blow one of them up to the size of the United States, the largest elevation would not even be half a millimeter high.”

A small personal note on the side: I actually have a piece of such laboratory silicon in my own mineral collection. The mineral trade in Berlin-Rudow once bought up a batch that was no longer suitable for high-tech processing due to a tiny production flaw. A truly fascinating metal that feels surprisingly light in the hand but has such weighty significance for our world.

LITHIUM: THE WHITE GOLD OF THE ENERGY TRANSITION

From the digital revolution, which was only made possible by silicon, Conway spans the arc to the next great global transformation: the energy transition. If we want to move away from fossil fuels and towards renewable energies, we face a massive problem: we must be able to efficiently store the electricity from the sun and wind. And this is exactly where the next star from Conway’s book takes the stage – a metal so reactive that it never occurs in pure form in nature: lithium. Conway dedicates the sixth chapter of his extensive work to this element.

Batteries play an absolute key role today. Interestingly, Thomas Alva Edison was already experimenting with lithium as a component of batteries at the beginning of the 20th century. The suitability of lithium for batteries quickly became clear, although the successful development of a lithium-based battery was a long time coming. Conway writes:

“But de facto, until the 1970s, no one succeeded in taming this unruly substance so that it could be used in a battery. Batteries are a form of fuel – though not a fossil fuel, but an electrochemical fuel. Inside a battery, a controlled chemical reaction takes place, which means you have to channel the explosive energy contained in these materials and convert it into electrical current. And no component was more explosive than lithium.”

It took until 1991 for the electronics group SONY to bring the first ready-for-series-production lithium-ion battery to the market – back then as a compact battery pack for their Handycam video cameras. That was the starting signal for a revolution. Since then, the demand for lithium has literally exploded, driven by smartphones, laptops, and above all by the rapid increase in electric cars.

To understand where this coveted raw material comes from, Conway takes us to South America, more precisely to Chile. There, in the so-called “Lithium Triangle” between Chile, Argentina, and Bolivia, lies the largest single lithium deposit in the world in the Salar de Atacama. Conway fittingly heads this subchapter with the title “White Gold.”

The Salar de Atacama is a breathtaking, expansive depression in which bright red lakes alternate with white mountains of salt and smoking volcanoes. The core of this area is the driest region on earth. This extreme dryness is no coincidence, but the result of a special geological location: this desert of sand, stone, and salt lies in a double rain shadow. To the east, the massive Andes block the clouds, to the west the Chilean coastal mountain range.

“Therefore, rain is extremely rare here. Some weather stations have never measured even a single drop.”

But why is there so much lithium exactly here? Conway clearly explains this geological puzzle:

“You can imagine the Salar as a kind of melting pot, with the volcanoes of the Andes on one side and a smaller mountain range on the other. Water comes from the Andes in the form of several rivers that flow into the basin through deep gorges – quebradas. Along the way, the water picks up tiny amounts of unusual minerals from the Chilean earth, but when it reaches the bottom of the valley, it finds no way out. Trapped in the depression, the water seeps into the gravelly subsoil and mostly evaporates there – after all, this is one of the driest regions on earth.”

The result of this millennia-long process is invisible but immense:

“The surface of the Salar is undoubtedly a stunning sight, but even crazier is what lies beneath it. The salt is 5 kilometers thick in some places. Elsewhere it forms only a thin skin, and underneath lie huge quantities of ancient brine that disappeared below the surface at least three million years ago and soaks the subsoil like a sponge.”

The extraction of lithium from this brine seems almost archaic compared to the high-tech production of silicon wafers. The primeval brine is simply pumped out from under the salt crust and directed into huge, shallow evaporation ponds. Then the work is left to the relentless desert sun. It is an extremely slow process. Over many months, the water evaporates, and gradually various salts precipitate – first sodium chloride, then potassium salts, finally magnesium salts.

At the end of this process, which takes over a year, the formerly pale blue liquid has transformed into a concentrated, yellow-green solution that glows almost as brightly as a neon sign. At this stage, it then contains about 25 percent lithium chloride – the raw material that keeps our modern, mobile world running.

The Salar de Atacama is by no means the only salar in the world – and it is not even the largest. Similar salt depressions can be found in other places in Chile, but also in the neighboring countries of Bolivia and Argentina. Together they form the so-called Lithium Triangle, one of the most resource-rich regions on our planet.

Probably the best-known of these salars is the Salar de Uyuni in Bolivia. With an area of around 10,500 square kilometers, it is more than three times as large as the Salar de Atacama, which extends over about 3,000 square kilometers. And even in absolute amounts, significantly more lithium lies dormant in the Uyuni. Bolivia has signaled the political will to unearth this treasure and even build its own domestic battery industry. At the time the book was written, however, actual progress was manageable. A major reason for this lies in the chemistry of the brine itself: although the Uyuni contains more lithium overall, its concentration per liter of brine is less than half as high as that of the Atacama brine. This makes processing significantly more complex and less economical.

But brine extraction, as practiced in Chile, is no longer the measure of all things anyway. The fastest-growing branch of the global lithium industry today is hard rock mining. The reason is pragmatic: blasting and removing rock is simply faster than waiting months for millions of liters of brine to evaporate. Australia has consistently followed this path and has meanwhile replaced Chile as the world’s largest lithium producer.

However, this progress has a serious catch. Hard rock mining is significantly more energy-intensive than brine evaporation and generates significantly more greenhouse gas emissions. It is one of the central ironies of the energy transition: the raw material that is supposed to enable our green future is being extracted in some places in a way that is anything but green.