TO WIN A game of Scrabble, start at the bottom of the periodic table. The 17 “rare earths” that reside there have longish names, such as dysprosium and praseodymium, which are replete with point-worthy letters. They share other traits, too. All are produced and used in minuscule amounts, yet are crucial to a range of high-tech goods, from batteries and renewables to weapons and medical devices. More important still, all are largely supplied to the world by China.