A 6,000-year-old amulet discovered in 1985 at Mehragarh, a Neolithic site in western Pakistan, has been analysed using a new photoluminescence technique.
     Having reached the limits of what they could learn from the amulet with traditional optical imaging techniques, researchers employed photoluminescence to examine the object's structure and composition in greater detail. They were surprised to discover that the artefact was made only of copper elements, which didn't seem to match what they had observed with conventional microscopes.
     The technique works by shining light on objects, allowing scientists to determine the spectrum re-emitted by the samples, and distinguish the different elements they contain. In this case, two copper oxides were present, suggesting the amulet was made from a very pure copper melt, which was poured into a prepared clay mould using wax casting - the earliest evidence of the use of such a technique.
     The use of pure copper may indicate the object had a particular status, and the fact that metallurgists used the lost wax technique so ong ago confirms the impressive capacity that people living at Mehragarh had to innovate. The same technique is still used today, nearly 6,000 years after the amulet was created.
     The team hope their method can be applied in a variety of fields - not only archaeology, but also geophysics, engineering, and environmental sciences.

Edited from International Business Times (15 November 2016)