Zircon grain (IMAGE) University of Copenhagen - Faculty of Science Caption Fig. 2. Crystals of the mineral zircon are tiny time-capsules that record the age of many events in Earth’s history. Dating zircon crystals like this was one of the two methods used to calculate the age of the Hiawatha impact crater. Credit University of Copenhagen Usage Restrictions none License Original 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.