Fulgurite is SiO2 that has been melted and solidified due to the impact of lightning. Sand, quartz, or silicon dioxide are the primary components of fulgurite, which can also take the form of clastic fulgurites.4 photos

When a lightning bolt strikes, it releases 109 to 1010 joules of energy. A lightning bolt can heat the channel through which it travels to temperatures as high as 30,000°C, which is five times higher than the surface temperature of the Sun. The temperature inside a lightning bolt is even greater than the melting point of sand (1600-2000°C), but whether the sand will melt depends on the duration of the lightning bolt, which can range from dozens of microseconds to several tens of milliseconds. The amplitude of the electric current impulse during a lightning strike is usually several dozen kiloamperes, but it can sometimes exceed 100 kiloamperes. It is these extremely powerful lightning bolts that create fulgurites, which are hollow cylinders made of melted sand.