Rare Earth

Written by: MA Wai-man           March 2011

Recently, there are many news report of "Rare Earth".  What actually is Rare Earth?

In fact, "Rare Earth" is a collection of seventeen chemical elements. They are: Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu), Scandium (Sc) and Yttrium (Y). They are hidden in the Earth's ore deposits. With the exception of the radioactive promethium, rare earth elements are relatively plentiful in the Earth's crust. However, because of their special chemical properties, mining and extraction of rare earth elements is complex. A large scale production of these metals was uncommon in the past and so they are collectively referred as "Rare Earth".

Rare earth are important components in many appliances, such as electronic products with magnets and/or lasers, computer memories, glass, camera lenses, batteries, fluorescent lamps etc. One of them, Gadolinium, is being used as the Magnetic Resonance Imaging (MRI) contrast agent for medical diagnosis purpose. After injection, Gadolinium in the contrast agent will accumulate in the abnormal tissues of the body, resulting in a greater contrast between normal and abnormal tissues. This facilitates doctors to better locate the irregular cells and tumors.

The technology employed for mining and extracting rare earth is relatively mature in China. The ores are mainly located in and around Inner Mongolia. Around 97% of the rare earth metals are now produced by China.

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