thumb|right|Aerodynamically shaped australite; the button shape is caused by ablation of molten glass in the atmosphere during reentry. Australites are tektites found in Australia. They are mostly dark or black, and have shapes including discs and bowls that are not seen in other tektites. NASA used the shape of "flanged button" australites in designing re-entry modules for the Apollo program in the 1960s.
thumb|right|Aerodynamically shaped australite; the button shape is caused by ablation of molten glass in the atmosphere during reentry. Australites are tektites found in Australia. They are mostly dark or black, and have shapes including discs and bowls that are not seen in other tektites. NASA used the shape of "flanged button" australites in designing re-entry modules for the Apollo program in the 1960s.
==History== Indigenous Australians from the Diyari group termed australites '' ("staring eyes"), and they were used as sacred objects or as cutting tools. Europeans found out about australites in 1857, when explorer Thomas Mitchell gave naturalist Charles Darwin a mysteriously shaped piece of natural black glass. Darwin thought that australites were of volcanic origin due to their similarity to obsidian, volcanic glass. Later, australites were called blackfellows' buttons and obsidian bombs''.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).