Presolar Grain (image) Field Museum Share Print E-Mail Caption Scanning electron micrograph of a dated presolar silicon carbide grain. The grain is ~8 micrometers in its longest dimension. Credit Image courtesy of Janaína N. Ávila. Usage Restrictions Please include credit 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.