I Am the Love Child of Unstoppable Force and an Immovable Object.

WHAT HAPPENS WHEN a multi-million-ton chunk of speeding interplanetary rock crashes into earth? I happen (at least in those instances where there is considerable silica at the impact zone). There was some speculation when I was first discovered in southern Bohemia in 1786 that I was the scattered leftovers from an ancient bottlemaking plant. Little did they know then of my much more mysterious cosmic origins. I am the only tektite (“space glass”) of gem quality, and according to some traders, the “true kryptonite.”

Who am I?