Chemistry, microstructure, and alpha decay damage of natural brannerite

► We examine the geochemistry and radiation effects of brannerite from worldwide localities. ► The samples are all amorphous due to the effects of alpha decay damage. ► Geochemical alteration is characterized by loss of uranium and gain of silicon. ► U-Th-Pb chemical ages generally are compared with known geological ages. ► The effects of lead loss and metamorphism are observed in specific examples.