A recent study examined a transparent material used in high-impact applications such as helicopter windshields at the molecular level to measure its toughness. Researchers at the University of Illinois Urbana-Champaign and the University of California, Irvine, followed a crack along a grain boundary in magnesium aluminate spinel, or transparent aluminum, adding new data about this unique crystal-structured material. Their paper is published in the Journal of the American Ceramic Society.