On the periodic table, rare earths are in a row at the bottom called the lanthanides (the neon green row). The elements from lanthanum on the left to lutetium on the right plus yttrium and scandium are called the rare earths.

Why are they important? They are needed in pretty much all electronics. The explosion of hand-held computers, like cell phone and tablets, has created ever more demand. The glass display, the magnets in the speakers, the headphones, the vibrating motors, all require rare earths.

Even more alarming is that all batteries contain rare earths. And batteries are becoming ever more important to fuel our insatiable need for portable devices. I can’t even count the number of batteries I carry with me, even when I go on “nature trips” like backpacking excursions.

I carry my cell phone, my Kindle, my GPS (with spare rechargeable batteries), a solar charger (with batteries) just on a hiking trip.

My Prius uses nearly 20 pounds of rare earths in its battery alone. There are over two million Priuses on the road.

Alright, we can agree rare earths are important.

Did you know that 97% of rare earths come from China? The Chinese have recognized that a monopoly on rare earths can be very valuable indeed. Why does the rest of the world not mine its own? The problem is that a major by-product is radioactive waste in the form of thorium. When the U.S. was still mining its own rare earth materials, much waste leaked into the environment, causing mines to be shut down. Alarmed by a Chinese monopoly, spurned by low labor costs, large deposits of the minerals, and lax environmental laws, other countries are now trying to catch up. The U.S., Russia, Australia, India, Brazil, and Vietnam are all looking for new deposits.

This is one reason to recycle old electronics. There are hundreds of millions cell phones, computers and other devices with on/off switches that sit uselessly in drawers, on shelves, in boxes and people’s houses – full of valuable rare earths that could be harvested. I harbor my share.

Now I know why it’s important to recycle my used batteries.