Quartz Crystals from Toba (IMAGE) Uppsala University Caption The researchers analyzed quartz crystals from Toba, and found a distinct shift in the isotopic composition towards the outer rim of the crystals. Credit Troll et al. Usage Restrictions May only be published in connection to reports about research from Uppsala University. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.