Criticality : When will rare-earth elements end ?

Written by Astrid Dhénain

May 20, 2022

Written by Astrid Dhénain

May 20, 2022

The development of our societies is based on the use of natural resources at our disposal. A resource can be a wheat field, as well as an oil slick or a river. Rare-earth elements are an increasingly talked about resource: they are indispensable for various daily activities. They are found everywhere, from our light screens to the generators of our electric cars.

Rare-earth elements: what are they?

Yttrium, Europium, Terbium, Neodymium or Dysprosium are all elements that belong to the rare-earth group. This group is composed of Scandium, Yttrium and Lanthanides.

Periodic table of elements (rare-earth metals framed in black)

Each of these elements plays a crucial role in the manufacture of any digital device.

The magnetic qualities of Neodymium and Dysprosium make them indispensable elements in the energy transition: the electric generators present in wind turbines as well as in electric cars owe their efficiency to these elements, in particular to their permanent magnet property.

For its part, the trio Yttrium-Terbium-Europium allows us to watch our favorite series in color on the screens. Thus, the green of our pixels is returned by Terbium, the blue by Europium and the red by the assembly of the latter with Yttrium.

Relative abundance of elements
(Rare Earth Elements – Critical Ressources for High Technology, USGS, 2002)

An increasingly exploited ressource …

At first, we drew these metallic resources from veins discovered on the surface. Then, thanks to technical progress and the use of fossil fuels, we were able to dig deeper and deeper mines, to extract sufficiently rich ores. However, like all non-renewable resources on our planet, rare earth stocks are finite.

To more accurately understand the challenges we will face (and to answer the question “how much time do we have?”), we need to clarify the concept of cut-off grade. Cut-off grade is the minimum amount of metal (or valuable materal) that must be present in the excavated and treated soil for it to be profitable. This threshold value depends on many factors, such as operating and financing strategies, economical constraints (financial institutions) or technical constraints (pit slopes, equipment sizes, etc). The limit therefore varies according to the company responsible for the extraction.. or to the stock market prices. The cut-off grade is thus an estimate of the quantity of ore that can be extracted at a suffciently reasonable cost to be profitable.

…and increasingly critical !

And that’s the challenge: there is no immediate risk of running out of these stocks, for a good reason… we don’t have the capacity! This is due to the non-homogeneous distribution of the reserves in the earth’s crust: the ores are present in abundance in two distinct rare earth concentration rates (the two bumps on the figure below). One (circled), represents the quantity of the richest ores in terms of value, therefore more easily exploitable. It is estimated that two thirds of these ores have already been mined! The other hump (boxed) represents the quantity of ores that contain rare earths in lower concentrations. The “pit” between these two humps is called a mineralogical barrier: there is an absence in the earth’s crust of ores with rare earth concentrations between these two humps.

Mineralogical barrier
(Bobert Ayres, Brain Skinner 1976)


The current state of the art does not allow us to access these reserves (and therefore most of these rare earths) at a reasonable cost. The consequence of the mineralogical barrier is that once the volume in the high concentration ore hump is fully consumed, we will have to turn to other solutions.

What future for those ressources ?

We can think, rightly or wrongly, that a major technological advance will allow us to extract rare earths from less concentrated ores, or to do without these materials by replacing them with others. We can also imagine that progress in recycling them will allow us to continue to manufacture digital tools in large numbers. But all these assumptions assume that other resources are in infinite quantities or particularly abundant and can be obtained without effort. By this we mean the rich energy carriers like oil, coal or uranium, which provide the majority of our energy. And we can already see the problem: these are also resources whose stocks are finite and whose depletion is undesirable (source of GHG emissions, strategic conflicts, etc).

Even if, despite the oil shocks, we still have oil to put in the tank of our cars, it will indeed become more and more expensive to extract. Added to this are the challenges of social and political dependence, and climate issues.

Unfortunately, this problem can be applied to all abiotic resources, i.e. mineral resources, which are not of biological origin. The more new technologies develop, the more we need a large diversity/quantity of elements of mineral origin. All these resources are linked to social, economic and political pressures that lead to great uncertainties in their accessibility. This variability in the availability of resources, depending on a multitude of factors, is discussed under the concept of criticality.

Do we then want to replicate this for rare-earth elements? The difficulty of extracting earths from ores that are less and less rich in rare-earth metals, among other things, will probably cause price increases in the near future.


Thus, criticality covers all the factors that could make a mineral resource unavailable on the market. This notion includes, beyond the ease of extraction, factors such as the monopoly of a country in production, world demand, geopolitical tensions, the possibility of substituting it by another resource with similar properties, etc.

Let’s take, for example, the case of neodymium, one of the rare earths essential to the energy transition we mentioned above. According to estimates provided by the European Parliament, 97% of the world production of this resource is provided by China. Let’s assume that this world power decides, for strategic reasons, to stop all its neodymium exports, in the same way that Russia recently decided to stop supplying Poland and Bulgaria with gas. One can imagine the disastrous consequences that such a decision would have, not only on the energy market, but also on all the sectors that depend on it (aeronautics, automobile, etc.).

Our world is one where millions, even billions of people can be deprived of a resource essential to their survival because an individual at the other end of the planet has decided to turn off the tap.

So, when will independence come ?

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