© Catherine JARRIGE / Mission archéologique de l'Indus / CNRS Photothèque
Map of the principal Indo-Iranic archaeological sites from the 7th to the 2nd millennium BC. At Merhrgarh, in present-day Pakistan, in the 1980s, a copper amulet from the ancient Chalcolithic period was discovered on land settled 6,000 years ago. The secret of its manufacture has been revealed thanks to a new approach using UV/visible photoluminescence spectral imaging. This amulet is the oldest known object made by the lost wax process. This process uses a model sculpted in a material such as beeswax, which is then encased in clay. Wax melts at low temperatures so it runs out easily when the clay is heated. Molten metal is then poured into the empty clay mould, taking the place of the wax.