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Wed October 16, 2013
Dr. Cornelia Class, Columbia University - Rare Earth Elements and Cell Phones
In today’s Academic Minute, Dr. Cornelia Class of Columbia University explains the importance of rare earth elements in the manufacture of electronics.
Cornelia Class is an associate research professor of geochemistry at Columbia University’s Lamont-Doherty Earth Observatory where her research interests include solid Earth geochemistry and dynamics. Her work attempts to understand the past and present geology of the Earth’s mantle. She earned her Ph.D. at the Max Planck Institute for Geochemistry in Mainz, Germany.
Dr. Cornelia Class - Rare Earth Elements and Cell Phones
We all love using electronics for work and recreation. Computers and cell phones are everywhere, and we like getting newer models more and more frequently.
But did you realize that materials required for many of these devices are coming from rocks that are millions of years old? Tiny magnets made of Rare Earth Elements, particularly Neodymium, are an essential component of many compact electronics. Rare Earths are metals that actually are not rare, but they rarely occur in concentrations profitable for mining. High concentrations of Rare Earths are found in very exotic igneous rocks, called carbonatites, which have unusually high carbon contents. Carbonatites are found almost exclusively where continents are starting to break apart to form what will eventually be a new ocean.
For example, the African continent is slowly breaking apart from Ethiopia to Malawi in the East African Rift, in most parts accompanied by volcanism. My colleagues and I are studying this process by investigating the composition and precise ages of resulting rocks, which include some carbonatites. In fact the East African Rift hosts the only historically active carbonatite volcano in the world, Oldoinyo Lengai in Tanzania. All other carbonatites we know of formed before humans existed. My graduate student Gary Mesko determined that separate carbonatites in our study area formed 160 million and 1.5 billion years ago. This shows that most carbonatites form only occasionally through Earth’s history. Of those few, even fewer have enough rare earth elements to be mined.
The only major source of Rare Earths in the USA is a now-closed mine in California, which is made of 1.4 billion-year-old carbonatite. The biggest producer globally now, is the about 1.3 billion years old Bayan Obo Mine in China.
This tells us that our lives today are built on rare geological processes, and the resulting resources are not being replenished at any significant rate. So, we have to wonder: what will be left for future generations?