Phenomenon caused by lightning strike into sand...

Fulgurite, or petrified lightning, is a natural hollow glass tube that forms in quartz sand (SiO2) when a lightning strike. It occurs when lightning strikes and raises the temperature of the sand above 1800°C, currently calming quartz. After cooling and merging, thick shapes are formed. The procedure takes about one second, and the obtained fulgurite shows the passage of lightning through the earth.

Petrified lightning can sometimes reach up to 15 meters deep in the ground and are several centimeters in diameter. Fulgurites are quite fragile and break when excavated from the soil.