Scientists have been blending mobile phones to find out what rare and precious metals are in them. Researchers at the University of Plymouth hope to help manufacturers source components responsibly and encourage us to recycle our old handsets. Dr Arjan Dijkstra, lecturer in igneous petrology, said the use of high value ores in mobile phones was putting "a significant strain on the planet". This video has been optimised for mobile viewing on the BBC News app. The BBC News app is available from the Apple App Store for iPhone and Google Play Store for Android.