This Gray Rock May Explain the Beginning of Life

Some of the rocks and minerals on our planet are really something to look at. Sparkly, colorful, translucent. But some of the others are, well, a little underwhelming. As far as looks go, this little gray rock isn't winning any beauty pageants. But its value comes from what it represents and what it can do. This is Shungite. It's a remnant of some of the earliest life on our planet and it offers a window into what Earth was like 2 billion years ago. We can even use Shungite to make our own lives better too. You're about to look at this little gray rock in a whole new way. Most of the minerals on Earth are made up of a smorgasbord of different elements. Silicon, oxygen, and aluminum to name a few. But Shungite is different. A lot of the time it's almost entirely made of carbon and there are different subclasses of Shungite based on what percent carbon they are. So Shungite is less of a mineral and more of a category since there isn't a specific chemical formula to define it. And if that's not confusing enough, you can also get Shungite-bearing rocks which aren't themselves Shungite but do have bits of it all scattered through them like chocolate chips in a cookie. Of course, carbon-bearing rocks aren't all that rare. Coal is the obvious one and the vast majority of that formed during the Carboniferous period. Way back then we had lots of giant plant life on land but not a lot of organisms adapted to decompose those big plants when they died. So instead of rotting away, those plants just hung around and eventually the pressure of everything else above them made the coal we know and burn today. But the thing that sets Shungite apart from all those other carbony rocks is their age. Because the oldest Shungite deposit that we know of is around 2 billion years old. Those ancient Shungites are found near a Russian village called Shunga which is also where Shungite gets its name. They formed in the Paleoproterozoic era long before plants or decomposers or anything multicellular had evolved. And because they're so old, there's been a lot of debate over what kind of living things all of that carbon came from. The Shungite-bearing rocks in Russia are over a kilometer thick and extend for around 9,000 square kilometers. There's thought to be more than 250 trillion tons of carbon contained in this one deposit alone. So some researchers thought that this was just too darn much carbon to have come from anything living, period. After all, not all carbon deposits have to come from living organisms. For instance, hydrothermal fluids in volcanic systems can dissolve and concentrate specific elements, including carbon, and form them into big ribbony deposits. But these non-biological processes aren't well understood and they usually result in a much smaller deposit than the scale-tipping Shunga site. On Earth, it's living things that have become the masters of the carbon cycle, and there's plenty of evidence to suggest that the Shunga material is organic. The thick Shungite-containing rocks are in clear layers that are also interspersed with other rocks like dolomite, volcanic ash deposits, and finally crystalline quartz deposits known as chert. We see that kind of pattern in places where marine life dies in big bursts, gets covered over by sediment, and then more living things fill in that gap. Rinse and repeat a few times and you get a sort of lasagna effect with organic and inorganic layers. Tasty. And when we peel apart our lasagna and just look at the Shungite, the microstructures inside the carbon layers tell their own story. When researchers looked at the rock through high-powered microscopes, they found evidence of filaments and tubes, the same kind of structures that are formed by bacteria. Plus, the isotopic compositions of carbon in both the Shungite and the surrounding carbonate rocks are consistent with biological processes too. So despite their great age, these rocks are thought to have been biological in origin after all, formed from tiny microscopic organisms and representing one of the oldest organic mineral deposits still in existence. Based on our geological lasagna evidence, we think the layers of Shungite formed in a shallow water lagoon at the edge of an ancient continent. Thanks to radioactive decay dating, we know that the oldest layer is 2.1 billion years old and the youngest is 1.9 billion years old. And while we know that microscopic prokaryotes had evolved in the oceans during the Archean eon, one to two billion years before our Shungite layer cake started growing, we also know that it took a long time for those critters to, like, do anything interesting. All those oldest life forms got their energy from chemical reactions and they used elements like iron and sulfur to power their metabolisms. But these were hard to come by in that wide ocean, so populations stayed pretty teeny. But by the time the Paleoproterozoic got started, bacteria had evolved a neat little trick called photosynthesis, and that's when things really started to take off. Using light to power their metabolisms, microbes were able to tap into an essentially unlimited energy source. As long as they could see the sun and had some basic nutrients, they could grow and reproduce. And that shallow sunlit lagoon off the coast of the ancient Russian continent was the perfect place for the mother of all microbial parties. It's still not clear what exactly caused those happy microbe communities to die off all at once to create the Shungite layers, but whatever it was, it didn't just happen at Shunga. There are carbon-rich deposits all over the world that date to around the same time, with the same isotopic signatures that we see in the Shungite. It's been suggested that this could represent one of the first mass extinctions on Earth, affecting the dominant form of life at the time, and leaving its trace as a massive carbon dump in some of the Earth's most ancient rocks. But they didn't all start out as rocks, because as it turns out, the Shunga deposit used to be a massive oil field. After all, the oil that we drill for and burn for energy came from microbial die-offs too, so these Shunga-era microbes were just doing it before it was cool. As those rock layers were heated up and buried deeper and deeper, the carbon in the dead microbes was baked into an amorphous oily substance, which concentrated in layers. For a few hundred million years too late to find that liquid oil, all that prolonged heat and pressure transformed the oil into solid carbonaceous Shungite. And Shungite can't be used like coal either, because the carbon is packed too densely for it to easily burn. But that doesn't mean it can't be useful in other ways, because the carbon inside these ancient rocks is sometimes arranged in a ball-shaped cage-like structure called a fullerene. Scientists have made fullerenes such as buckyballs and carbon nanotubes, and they've been studied a ton in the realms of materials and electrical engineering. But they form in nature too, and the first place that researchers found these all-natural fullerenes was in Shungite. One of the properties of these fullerenes is that they can trap other elements inside their carbon cages, so they've been used to help purify water. But before you start switching out your water filters at home with Shungite, you should know that the fullerene cages can go both ways. Sure, they can trap all those harmful elements, but that doesn't mean they'll hang on to them forever. One study found that untreated Shungite can actually end up releasing harmful heavy metals into the water it's meant to be purifying. But even if Shungite water filters have some kinks to work out, the mineral still has a few exciting applications. There are a lot of industrial processes that rely on components made of pure or nearly pure carbon. And since Shungite is pretty much just carbon, that means you can use it in place of a lab-made carbon component. For instance, electrochemical analysis uses electrodes made of different materials to investigate chemical properties using an electric current. Normally, these kinds of applications use electrodes made of an artificial carbon crystal called glassy carbon. But in 2023, researchers tested natural Shungite under similar conditions and found that the purest pieces work just as well as the man-made stuff. This means Shungite electrodes could offer a cheaper alternative to glassy carbon, which could help researchers test things like new anti-corrosive coatings and detergents. The electrodes could also be integrated into sensors for heavy metals in the environment, and even for drugs in pharmaceutical and clinical settings. Speaking of sensors, scientists have tested out another really cool potential use for Shungite in construction. The idea here is to turn building materials into their own stress and damage sensors. When you grind up Shungite into a fine powder and mix it into cement, you can alter its conductivity, aka how well it can pass an electrical current through it. And they found that when the concrete binder contained around 40% Shungite by weight, the Shungite particles were able to form a continuous conductive network throughout the material, which allowed electrical currents to pass through the concrete. This opens up a world of possibilities for electrically conductive building materials, including better heated floorings or self-de-icing roads and sidewalks. Not only that, but they found that the material's resistance to electricity changes when it gets compressed, meaning that you could essentially make concrete that alerts people when it gets damaged, even if that damage is only internal. It's important to note that these are still active areas of research and none of these Shungite-powered tech options have come to the market yet. But with over 250 gigatons of material sitting in the deposits around Shunga alone, there's plenty of raw material for researchers to work with. So these ancient fossils-turned-minerals might just be the key to some truly futuristic tech someday. And SciShow Roxbox subscribers can look forward to receiving their own chunk of Shungite in the mail. Every month, we bring you a hand-selected mineral or fossil that's perfect to add to your collection, whether you're a new collector or a seasoned rockhound. But we don't limit the fun to just the subscribers. We have plenty of fan-favorite minerals for sale on our website. So you can pick and choose your perfect assortment. Head to complexly.store slash rox to check it out and get yourself something that really rocks. Thanks for watching.