Its called aerogel

It sounds like a gel but this is a solid, tougher than glass. This crazy material is a product of Nanotechnology. Aerogel is like foam, principally made out of air (99.8% air).

Aerogel is made from alcogel (a gel made by polymerisation silicon alkoxide with water in a mixing solvent). The alcogel is dried and liquid is extracted from the solid silica. The remaining solid is then filled with air to 50-99% of the volume of the original alcogel (Aerogel - gel filled with air).

Aerogel is 1000 less dense than glass, but is 39 times more insulating than the best fiber glass. It also has a low thermal conductivity, meaning a 3,000°F blowtorch under a thin slice of Aerogel will not affect objects above it. You can find out more on the web.

Aerogel was used by NASA on Mars' Pathfinder. It has at least 15 entries in the Guinness book of records. Now watch this video of a blanket made from Aerogel : Aspen Aerogel.

Properties :

Melting point : 1,473 K (1,200 °C or 2,192 °F)

Density : 3 milligrams per cubic centimeter.

Here are some link related to Aerogel :
http://stardust.jpl.nasa.gov/tech/aerogel.html
http://www.unitednuclear.com/aerogel.htm
http://homepages.cae.wisc.edu/~aerogel/aboutaerogel.html