Science: Synthetic Mica

The remarkable properties of high-grade sheet mica as an insulator make it invaluable as a strategic war material, where it is essential for radio tubes, radar equipment, condensers, airplane sparkplugs. But the U.S., the world’s largest user of mica, produced only 135 tons in 1948, had to import another 10,000 tons, chiefly from Brazil and India.

This week in Washington the National Bureau of Standards announced that mica had been successfully synthesized by three of its scientists, Dr. Herbert Insley, Alvin Van Valkenburg and Robert Pike. The new product is equal to natural mica as an insulator, far superior in its ability to withstand high temperatures.

Blending powdered quartz, magnesite and bauxite, the bureaumen added a crystallizing agent (fluorosilicate compound) and melted the ingredients in a platinum-lined crucible at nearly 2,500° F. As the furnace cooled, mica sheets grew from tiny “seed crystals” at the coneshaped bottom of the crucible. Because crucibles lined with carbon or ceramic failed to do the trick, the bureau scientists used expensive platinum, hope to reduce costs by melting down the metal and reusing it time & again.