Fulgurite, petrified lightning

Fulgurite is a hollow glass tube of molten sand caused by a lightning strike.

Thunderbolt

The heat from the lightning melts the sand and forms a hollow tube. It is also known as petrified lightning because fulgurite hardens in the shape of the thunderbolt.

Storm in the desert

This piece comes from the Sahara and is found in a hollow. Fulgurieten occur almost always in hollows and not, as you would expect, on the dune tops. In the desert Lightning usually strikes in places that are closest to groundwater.

Size

Pictures are enlarged to detail, look at the last picture for the actual size.