| Many parents will have given their children electric toothbrushes for Christmas, hoping that the sensors that buzz after two minutes will keep them brushing longer than their flimsy elbow grease.
Both generations may, however, be ignorant of the fact that in that time the toothbrushes produce more than 62,000 strokes; that the power to generate such motion comes from tiny magnets using three rare metals, neodymium, dysprosium and boron; and that some of these metals are so coveted that in 2010 they were at the centre of a dangerous rift between China and Japan...............................................Full Article: Source
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