Piece of a Comet
Jet Propulsion Laboratory https://www.jpl.nasa.gov/ Feb. 21, 2006
This image shows a comet particle collected by the Stardust spacecraft. The particle is made up of the silicate mineral forsterite, also known as peridot in its gem form. It is surrounded by a thin rim of melted aerogel, the substance used to collect the comet dust samples. The particle is about 2 micrometers across.