The inside of a Meteorite. "Fun fact: Widmanstätten patterns found inside meteorites cannot be replicated on Earth. This is because the patterns can only be formed in extremely slowly cooling nickel/iron mixtures (over millions of years) to form two different alloys: Taenite and Kamacite, that form slightly different crystal structures."
Moldavite was formed when a meteorite impacted the earth’s surface. The violence of the shock, and the intense heat generated, created a “glassy form” that was propelled towards the banks of the Vitava river in the Czech Republic (“Moldau”, in German), resulting in its name.