Aerogel is a form of solid matter, one of the least dense solids in the world. The common aerogels are silicon aerogels, but carbon aerogels are also present. The lightest silicone aerogel available is only 3 milligrams per cubic centimeter, three times heavier than air, and is also known as "frozen smoke" or "blue smoke."
Characteristics of aerogel
* High porosity, up to 99.8%;
* Nanoscale holes (20 ~ 100nm) and 3D nanoskeleton particles (2 ~ 5nm);
* High surface area, up to 1000m2/g;
* Low density, as low as 0.003g/cm3;
* The unique structure of aerogel determines its extremely low thermal conductivity, which can be as low as 0.013W/(m·K) at room temperature;

* Low strength, high brittleness, due to its large surface area and porosity, very low density, resulting in very low strength