Cathode Luminescence Image (image) Johannes Gutenberg Universitaet Mainz Share Print E-Mail Caption Cathodoluminescence image of a typical zircon with clearly pronounced concentric zoning. This zoning is evidence of changes in the local chemical composition of the host magma during crystal formation. Credit photo/©: Alfred Kröner Usage Restrictions This image may only be used in connection with the press release "Mineral discoveries in the Galapagos Islands pose a puzzle as to their formation & origin", issued by Johannes Gutenberg University Mainz on October 19, 2018. Share Print E-Mail 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.