When was the last time you thought about the battery or camera on your phone? You probably didn’t think about magma cooling deep within Earth or rainwater gradually altering rocks over time.
Yet much of what makes up your phone before it becomes a slick sheet of glass and metal is geological in origin.
Electric vehicle batteries require lithium. Many battery designs include nickel or cobalt as well. Copper wires carry electricity through motors and power lines. Rare earth elements can be concentrated into powerful magnets in wind turbines or electric vehicles.
We refer to them as critical minerals. Critical doesn’t necessarily mean that the element is uncommon on Earth. Rather, it means that the element is used for something important. Also, an interruption in supply could be hard to replace. U.S. Department of Energy looks for both of those things when they assess materials.
It all starts with the fact that Earth is not uniform. Ore deposits do not occur everywhere. They need specific rocks and a whole history of geological events. Sometimes it’s about the way magma cooled to make useful concentrations. Sometimes it’s about groundwater moving and depositing elements through cracks. Sometimes it’s about weathering at the surface taking some elements away or concentrating others.
In fact, the same element can arise from a variety of geological processes. Consider lithium. Some lithium comes from pegmatites, which are exceptionally coarse-grained igneous rocks. They are formed in the final stages of cooling magma.
Water and elements that didn’t easily fit into earlier minerals end up concentrated in the last bit of melt. These elements can be incorporated into minerals like spodumene.
Other lithium sources are salty groundwater in closed desert basins below ground. Water is entering the basin but there’s no way to get to the ocean, meaning that over long periods as water evaporates, dissolved elements may become more concentrated. The U.S. Geological Survey says that most of the world’s lithium production comes from pegmatites and closed-basin brines.
Nickel and cobalt are different. Important deposits can occur where hot rainfall strongly weathers ultramafic rocks that were initially rich in iron and magnesium. Over vast stretches of time, the water leaches more mobile elements from the rock. Nickel can be concentrated at higher levels. Cobalt may also be enriched in certain parts of the weathered zone.
These are called laterite deposits. A USGS deposit model explains that they are often found close to the equator. That’s because you need the right climate and parent rock to weather strongly.
In this case, we can tie the location of an ore deposit to ancient rocks. We also can relate it to years of chemical weathering at the surface.
Copper is often associated with plate tectonics. Much of the world’s copper comes from massive deposits known as porphyry copper systems which occur near convergent plate boundaries, where one tectonic plate is sinking below another. Magma is rising through the crust. Hot fluids circulate around the magma, depositing copper-bearing minerals in a broad zone of fractured rock.
Individual pieces of this rock may contain only small amounts of copper. The deposit is important because the zone of mineralization can be so extensive. The USGS porphyry copper model estimates that this type of deposit accounts for around 60% of global copper supply.
Rare earth elements present a different geological puzzle. Some may be concentrated in carbonatites, a rare type of igneous rock that is composed mainly of carbonate minerals. A USGS review says that carbonatites host the highest concentrations of rare earths in igneous rocks.
Not only do we have to find rare earth elements, but their chemical similarity also creates difficulties in distinguishing one from another. It’s the history of Earth that determines the ore. It’s our technology and policies that influence refining capacity.
The International Energy Agency notes that in 2024, the average share of the three countries with the largest refining capacity was 86% for key energy minerals. That concentration can make a supply chain vulnerable even if there’s mineral resource in more than one area.
And demand continues to increase. The IEA’s Global Critical Minerals Outlook 2026 says that by 2040, demand for critical energy minerals will be nearly double what it is today based on current stated policies. For lithium, demand increases more than triple in that scenario. Copper increases the most in total mass because you need a lot more of it to build out electric grids.
But that’s not the only way to secure the future. There is still the possibility to recycle materials from previous uses, and there are possible new battery technologies that could lessen our reliance on certain materials. However, recycled material will not be able to meet all the needs of a rapidly expanding system.
That’s why the work of geochemists is so important, not just in a lab. The information we can gain from minerals and trace elements can give us an idea of how the deposit formed. We can use this information to guide our exploration to potentially discover deposits which are covered in soil or younger rock layers.
We often feel that modern technology exists on a plane of its own. It comes to us all shiny and wrapped up. We rarely see any hint of its origins. Each battery contains a slice of Earth’s history. Each piece of copper wiring is a link to an ancient tectonic event.
Modern technology isn’t just digitally based. It’s geologically based. Its foundation is hidden.
