Cover image:

Spontaneous fission tracks in a detrital apatite crystal from the Todos Santos Formation sandstone, the State of Chiapas, Mexico. These linear damages, which show random directions, were formed in apatite by the spontaneous fission of trace amounts of natural uranium. Polished apatite was etched in 5.5N HNO3 a at 21 °C for 20 s to reveal 238U spontaneous fission tracks. Photomicrograph by Fanis Abdullin and Jesús Solé.