cathode luminescence image (IMAGE) Johannes Gutenberg Universitaet Mainz Caption Kathodenlumineszenz-Bild eines typischen Zirkons mit deutlich ausgeprägter konzentrischer Zonierung. Diese Zonierung zeigt unterschiedliche Spurenelement-Konzentrationen während des Kristallwachstums. Credit Foto/©: 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. 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.