learn-a-little:

Petrified Lightning: Natural glass formed by lightning strikes is called fulgurite. It is created when a lightning strike hits a sandbank, blowing a super-heated hole right through it. This quickly cools into a beautiful glass. The name comes from Latin fulgur, or lightning.

(Image credit to flickr, Carion Mineraux, and Nature. Thanks Grandma.)

(via mothernaturenetwork)