The Mystery of the Mehrgarh Amulet | 6000 Year old | lost-wax casting

"Discovered in Pakistan in 1985, the Mehrgarh wheel amulet, 6000 years old, has long remained an enigma. Using new analytical techniques, a team of researchers has managed to unravel the secrets of the manufacturing process of this copper amulet, the first known object to have been made using lost-wax casting-a technique at the origin foundry arts."

"Photoluminescence spectroscopy is a key method to monitor defects in semiconductors from nanophotonics to solar cell systems. Paradoxically, its great sensitivity to small variations of local environment becomes a handicap for heterogeneous systems, such as are encountered in environmental, medical, ancient materials sciences and engineering. Here we demonstrate that a novel full-field photoluminescence imaging approach allows accessing the spatial distribution of crystal defect fluctuations at the crystallite level across centimetre-wide fields of view. This capacity is illustrated in archaeology and material sciences. The coexistence of two hitherto indistinguishable non-stoichiometric cuprous oxide phases is revealed in a 6,000-year-old amulet from Mehrgarh (Baluchistan, Pakistan), identified as the oldest known artefact made by lost-wax casting and providing a better understanding of this fundamental invention. Low-concentration crystal defect fluctuations are readily mapped within ZnO nanowires. High spatial dynamics-photoluminescence imaging holds great promise for the characterization of bulk heterogeneous systems across multiple disciplines."

Sources:
https://www.dailymotion.com/video/x6fossm (2018)
https://news.cnrs.fr/videos/the-mystery-of-the-mehrgarh-amulet
https://www.youtube.com/watch?v=ZS9EL-VujJc (2016)
https://www.wissenschaft.de/geschichte-archaeologie/raetsel-des-amuletts-von-mehrgarh-geloest/
https://www.nature.com/articles/ncomms13356.pdf