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One consequence of the growth of microelectronics has been an exploration of the periodic table reminiscent of European navigators' search for the spice islands half a millennium ago. Then, as now, the objective was material of great rarity and value, which was needed in only small quantities but which did jobs that nothing else could manage. In the case of spices, such as nutmeg, cloves and mace, this job was to enhance the taste of food and demonstrate wealth and sophistication. They were so valuable that wars were fought to control their supply in some cases.
In the case of indium, gallium and tantalum it is their unique electrical properties that are of interest. Indium-tin oxide, for example, is both transparent and electrically conductive. Without it, liquid-crystal display screens would be much harder to make. Meanwhile tantalum (used as an insulator in mobile-phone chips) once became so valuable that it, too, helped drive a war—the civil war in eastern Congo, where its ore has been dusted over the countryside like icing sugar by ancient volcanic eruptions.