Diamonds are a girl's best friend. Give a bag of charcoal, soot, or graphite to a lady and you won't get nearly as warm a response. That's unfair in a way, because all four are made of exactly the same basic element: carbon.

Whether you have diamond or soot or graphite depends only on the way that the atoms of carbon are arranged. In a diamond, the carbon atoms form triangular pyramids with one atom at each vertex and one in the center. This is a strong and stable configuration, and diamond is famously hard. In graphite, on the other hand, the carbon atoms form hexagons with an atom at each vertex. These hexagons line up as layers of flat sheets. Since the sheets are not strongly coupled with each other, graphite is slippery and a splendid lubricant. As for soot and charcoal, the atoms can be all over the place in a great variety of arrangements.

All this has been known for more than a century. Furthermore, until 1985 every authority on chemistry would have told you that no other basic forms of carbon could exist, providing one more example of my favorite scientific motto: "It's not the things we don't know that cause the trouble, it's the things we know that ain't so."

The discovery in 1985 of a third elementary form of carbon was a shock for two different reasons. First, the existence of the third form could have been predicted, or at least conjectured, at any time since the middle of the eighteenth century. In fact, it had been suggested in 1966, as a piece of near-whimsical speculation, by a science columnist. No one took any notice. Second, and almost a disgrace to a self-respecting chemist, the third form is not hard to make. In fact, it had been sitting right under our noses, waiting to be discovered, in the soot produced by a hot carbon fire. Every time you light a candle, at least some of the smoke will contain this new and previously unknown form of carbon.

It's actually not just one new form, either, but a whole family. The simplest and most common has sixty carbon atoms arranged in a round hollow shape that looks like a tiny soccer ball (and I do mean tiny - it is less than a millionth of a millimeter in diameter). The next simplest form has seventy atoms, and resembles a miniature rugby ball. After that come bigger versions with more atoms (76, 84, 90, and 94), then a variety of shapes including hollow closed tubes.

The newly discovered forms of carbon were given the horrible name of "buckminsterfullerenes," after the inventor Buckminster Fuller, who had used similar shapes in the design of geodesic domes. That was too much of a mouthful for most people, so they quickly became "fullerenes," or, for the small round ones, "buckyballs."

Fullerenes were discovered by an oddly indirect method. A British chemist, Harold Kroto, was studying how certain stars might generate long chains of carbon molecules in open space. And in the United States, at the Houston campus of Rice University, American chemists Robert Curl and Richard Smalley had the right lab equipment to simulate a carbon-rich star environment. The team got together, did the experiment and, as predicted, found evidence of a variety of carbon clusters. The trouble was, as the carbon vapor was allowed to condense everything faded away except evidence of 60-atom clusters. The team realized, after considerable brainstorming, that these clusters had the totally unexpected shape and structure of the buckyball.

At first fullerenes could be made only in minute quantities, so research on them was difficult. But in 1990 a German team discovered a simple production method. Burn a graphite rod electrically, and the soot contains a substantial amount of fullerenes. Now any chemistry lab that wanted fullerenes for research could easily buy them. And they did so, in ever-increasing numbers. Today the most frequently cited chemistry papers all seem to be on the subject of fullerenes, and the 1996 Nobel Prize in chemistry went to Robert Curl, Richard Smalley, and Harold Kroto.

Now for the question of the day: We have fullerenes, a new form of carbon. What are they good for, apart from winning Nobel Prizes?

Well, they are being used to improve the growth of diamond films. Fullerene tubes form components of atomic-scale microscopes. And because they are hollow, buckyballs can trap other atoms inside them, to provide miniature cages as "chemical test sites." They are also phenomenally robust and stable, and may lead to materials stronger than anything we have today. And under some circumstances they become superconductors, offering no resistance to the passage of an electrical current.

These are interesting research areas, but none is likely to make you run off to buy stock in Fullerene, Inc. My preferred answer to my own question is that it is too soon to say. Like lasers back in 1965, fullerenes are a solution waiting for a problem. And like lasers, fullerenes will become enormously valuable technological tools in the next thirty years.

Note: There are now Web sites devoted exclusively to fullerene research. Contact me if you are interested.

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