Working Knowledge: Rock Clock; March 2004; Scientific American Magazine; by Mark Fischetti; 2 Page(s)

Step on a hunk of quartz in the dirt, and you'll think nothing of it. But carve one of the stone's crystals into a tiny tuning fork, and you'll have the key component for the watch ticking on your wrist.

Almost 90 percent of today's watches are electronic. Batteries provide the power to turn the hands or fire the liquid-crystal display, but quartz oscillators - essentially, vibrating tuning forks - provide the chronometers' steady beat. "Even a cheap quartz watch is accurate to one or two seconds a month," says Lou M. Galie, vice president of research and development at Timex in Middlebury, Conn. "Far more precise than expensive mechanical watches."