It's nice to be sought after -- especially when you're named for the king of frustration and disappointment. An undistinguished No. 73 on the periodic table of elements, tantalum finds itself newly admired for its use in thin-film coatings for optical networking. Demand by the semiconductor and telecommunications industries boosted US sales of tantalum capacitors 15 percent in the first half of 1999, compared with the same period in 1998, reported the US Geological Survey. Tantalum is used, mainly in metal powder form, in cellular phones, pagers, computers and other electronics, said Larry D. Cunningham, a survey office commodity specialist. It is highly ductile, resistant to corrosion and a good conductor of heat and electricity. The modest spike in the tantalum market, and speculation that telecommunications equipment suppliers need it, prompted one US supplier to announce in April that it is warehousing several thousand pounds of tantalum plate for sputtering targets. "Large sputtering units are becoming more popular. It's going to require tantalum plate instead of small chunks," said Don Raifsnider, vice president of Target Materials Inc. of Columbus, Ohio. Optical Coating Laboratory Inc. of Santa Clara, Calif., has used tantalum as a high-refractive-index material for 30 years, said Bryant Hichwa, director of optoelectronic research. "There is a huge interest in the telecommunications market, and this is one of the materials that is used." The tantalum market took a record ride in 1980, Cunningham cautioned, rising to $118 a pound on speculation that it would be widely used. It fell to about $20 a pound in 1982 and sells for about $45 a pound today. There has been only a modest rise in price this year over last, and the world supply of tantalum -- ore, powder, ingot and plate -- is considered adequate. Other materials can be substituted for tantalum with varying results. Before you stockpile tantalum yourself, Cunningham said, be sure you've got a buyer.