An interesting infographic found below inspired me to start thinking about rare earth elements. Anyone with a stake in mining or technology has heard of, and potentially worried about the supply of, rare earth elements. We often hear that they’re vital to many emerging industries, including personal electronic devices, green energy, and futuristic materials.

But just what are the rare earth elements? And where are they found and mined? In this article, the first of a two part series, we’ll take a look at the science behind the rare earth elements and their importance to modern technology. Next time, we’ll focus on the economics and mining of the rare earth elements.

Uses for Rare Earth Elements

The rare earth elements are metals that occupy a position in the middle of the periodic table. They sport exotic sounding names such as PraseodymiumPromethium, and Ytterbium.

Why are these elements so useful and sought after?

In many cases, they allow us to make things smaller, stronger, or more accurate.

Neodymium, for example, is used to make extremely small, powerful magnets. These magnets have a major use in consumer electronics, including vibration sources in cell phones and data writing components in hard drives. In addition, they allow for the creation of more efficient generators and electric motors for technologies such as wind turbines and electric cars.

Other rare earth elements, such as Yttrium, terbium, europium, give off vivid colours when stimulated electrically. These elements make up an important component of the vibrant, high resolution digital displays found on modern consumer electronics.

Mining Rare Earth Elements

It’s clear that rare earth elements are important in today’s world. Unfortunately, they are very difficult to mine.

It’s often said that the rare earth elements are difficult to mine because of their rarity. Many journalists cite the case of Tellurium, an element required for the construction of solar panels. It makes up only one ten millionth of one percent (0.0000001%)  of the earth’s crust. Silver is seventy times as common, and even gold is about ten times as common as Tellurium.

In reality, Tellurium is much rarer than most of the rare earth elements. In fact, most rare earth elements are more common in the crust than precious metals (you might want to check out this interesting chart showing the relative concentrations of different metals in Earth’s crust).

In the end, the reason it’s difficult to mine rare earth elements isn’t that they’re rare. Instead, it’s because there are very few natural mechanisms for concentrating rare earth elements into ores or veins that can be mined economically.

Unlike precious metals, which are often concentrated by circulating fluids, rare earth elements can only form in very specific conditions. The most common mechanism for their formation is the formation of alkaline magmas. In this case, very limited partial melting of local rocks allows the rare earth elements to be forced out of the crystal lattice of the source and concentrated in the molten portion of the rock. When the magma cools, it becomes an ore body containing relatively high concentrations of rare earth elements.

Most rare earth mining operations target these alkaline ore bodies or placer deposits made up of their eroded remnants. We’ll talk more about the mining of rare earth elements in part 2 of this series.

Sustainable Technology – An infographic by the team at vouchercloud