Two examples of iron meteorites, typical of those in Chladni's collection. Tektites are small glassy objects resulting from asteroid impacts with the earth, cooling from molten glass to a solid before falling back to earth. Moldavites are a specialized form of green glass tektite, formed from the impact of a giant meteorite that caused the Nördlinger Ries crater in Bavaria. Almost all moldavites have been found in southern Bohemia.