Fulgurites (from the Latin fulgur meaning thunerbolt) are natural hollow carrot-shaped glass tubes formed in quartzose sand or soil by lightning strikes. In the right kind of sand the extreme heat generated will form silica glass shapes that trace the path of the lightning. These structures are also sometimes referred to as petrified lightning. The glass formed is called lechatelierite which may also be formed by meteorite impact and volcanic explosions. As it is amorphous it is classified as a mineraloid.