Portraits in Carbon

It’s hard to avoid the number six in talking about carbon: It’s the sixth element in the periodic table, and normally has six protons and six neutrons in its nucleus and six electrons hovering in loose formation around it. This form, called carbon 12, accounts for 99 percent of all carbon (carbon 13 and 14 account for the rest). As a substance, pure carbon comes in several guises, but among the most important are graphite (which is typically soft, black, slippery, and flaky); diamonds (which can be any of several colors, or colorless, and are as hard as elements come); and amorphous carbon (such as coal and soot). Carbon is abundant in the Earth’s crust and biosphere, and as coal costs as little as 1.2 U.S. cents per kilogram. As natural diamonds, however, it can cost thousands or even millions of dollars per gram. The name derives from the Latin carboneum, but is rendered kohlenstoff in German, uhlik in Czech, and sekitan in Japanese.

Oh, and carbon is the basis of more than 20 million chemical compounds and thus of life as we know it.

Those are the raw, actuarial facts, perhaps carbon’s dullest mugshot face. But carbon is more interesting than these facts suggest, and like a quick-change artist has many faces.Here are five more...