Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!bcm!dimacs.rutgers.edu!aramis.rutgers.edu!athos.rutgers.edu!nanotech From: john@granada.mit.edu (John Olson) Newsgroups: sci.nanotech Subject: Re: Diamonds? Keywords: diamonds, bones Message-ID: Date: 5 Apr 91 03:02:49 GMT Sender: nanotech@athos.rutgers.edu Organization: MIT Lines: 16 Approved: nanotech@aramis.rutgers.edu Diamonds have a big disadvantage over bone in that diamonds are thermodynamically unstable. At all temperatures, graphite is the more stable state for carbon. If you heat up a diamond--even under pressure-- it will mostly revert to graphite. the only reason they last is that the diamond --> graphite reaction is very slow at normal temperatures. And the only reason we see diamond at all is that there is an equilibrium between graphite and diamond. So when you do the Superman synthesis (coal --> diamonds under high pressure and temperature), most of the graphite just stays graphite. Now, that's not to say that a nanomachine (or a cell) couldn't make diamond, but it will be more difficult to synthesize than materials which can be thermodynamically stable. When a diatom makes its shell out of silica, well, silica will precipitate into a solid without the diatom's help. The diatom just has to make a frame for the silica to sit on. Similarly (as JoSH pointed out) for teeth and bones, the minerals will precipitate out on their own.