paul and I ordered some aerogel from United Nuclear, fine purveyors of radioactive materials, super strong magnets, and other fine materials. I've long wanted aerogel ever since I saw ghostly pictures of this substance, which holds the Guinness world record for lowest-density solid, best insulator, and thirteen other records. I received two dime-sized pieces. They aren't as cool as an entire brick of aerogel, but at $40 for even these small bits, a brick is rather out of the question.
The aerogel feels like you're handling an impossibly light and miniaturized piece of pumice and it's just as prone to shedding little bits of itself. It's 90-99.8% air and the edges of the pieces seem barely defined. When the aerogel is placed against a dark background it's like blue smoke that comes out of a tailpipe when a transmission has gone awry. Against a white background it nearly disappears into a faint outline -- a lot of what you're seeing for the clear piece in the photo is little bits of the blue velvet from the packaging stuck to it. The blue smoke/clear effect is due to Rayleigh scattering -- the scattering of light by particles smaller than the light's wavelength. It's an extremely strong dessicant as it's essentially the same chemical makeup as the silica gel dessicant packets you sometimes get in packaging. You have to be careful holding it as it will suck all the moisture out of your hands. You also have to be careful as it isn't very difficult to crush it into smaller bits.
Making aerogel seems a bit out of the question for my resources. Either one must be able to make alcohol a supercritical fluid (280 C/1800 lbs per sq inch), hard and also highly explosive, or you need access to liquid carbon dioxide and make it a supercritical fluid (600-800 lbs per sq inch). (History of aerogel and description of how to make).
One of the questions people seem to have about our pieces is, "What are we going to do with them?" Well, we probably won't use it to catch comet samples, and I don't think I'll be using it as a microchip insulator. For now I think I'll blowtorch one of the pieces and then keep the other on my shelf :).