Desert glass: sand turned to stone

Transcript

Desert glass is natural glass made when sand is suddenly fused by lightning or by the heat of a meteor impact, then cooled into rock-like material. With lightning, the heat is extreme enough to melt silica-rich sand in under a second, leaving hollow glass tubes called fulgurites beneath the surface. With impacts, the collision releases intense heat and pressure that melt sand and rock into impact glass, sometimes preserving clues of a meteorite strike long after the crater has eroded away.