Fulgurites

Fulgurites are not related to meteorite impact. They are useful for comparison with the impact glass. According to Wikipedia Fulgurites (from Latin fulgur 'lightning', and -ite), commonly called "fossilized lightning", are natural tubes, clumps, or masses of sintered, vitrified, and/or fused soil, sand, rock, organic debris and other sediments that sometimes form when lightning discharges into ground.