Shock Lamellae (IMAGE) University of Pennsylvania Caption Shock lamellae are formed when lightning hits rock, the study found. Here, a single lamella is seen under a transmission electron microscope. Lamellae appear as straight, parallel lines and occur when the crystal structure of a mineral deforms in response to a vast wave of pressure. Credit University of Pennsylvania Usage Restrictions In context of reporting 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.