Aerogel is one of the most impressive materials humans have created...so far.
This vial contains 25mL (approximately 1 heaping handful) of silica aerogel particles—the world's lightest known solid material. Commonly called "frozen smoke", it is safe to touch, hydrophobic (repels water), and an outstanding insulator. This is one of our most popular items and essential for any science enthusiast's collection.
Aerogels are a group of materials in which the liquid portion of a gel has been replaced with a gas. It was first created as a result of a bet.
Being the lightest solid material know, aerogels are up to 99.8% air. Its also has the lowest thermal conductivity of any know solid which means it makes a great insulator.
Due to its high porosity, NASA has even used aerogel to collect interstellar dust particles in outer space.