This spectacular Thailandite from the Khorat Plateau region of northeastern Thailand, exhibits exceptionally well-developed skin splits. These formed after the skin had cooled sufficiently to react in a brittle manner while the interior remained soft and gooey. When this water balloon-like blob splatted, the skin split open revealing the viscous interior. Note the contrast in skin ornamentation between the two regions.
I am often asked if I consider these to be “stretch” tektites. I don’t, but in principal they are exact equivalents. The classic Nininger stretch tektites involve a bending angulation, where the degree of angulation is matched by a similarly angled split along the opposite edge. The difference is academic, but good stretch tektites following this definition are quite rare and expensive, while skin splits or starburst rays are quite common. The starbursts typically radiate from an indentation along the rim , possibly reflecting an impact point. The pattern is often termed a “dragon track” in China.