Fluorescence and Phosphorescence.

Minerals that become luminescent during exposure to ultra-violet light, x-rays, or cathode rays are fluorescent. If the luminescence continues after the exciting rays are shut off, the mineral is said to be phosphorescent. . . . [S]ome minerals that appear only to fluoresce can be shown by refined methods to continue to glow for a small fraction of a second after the removal of the exciting rays. Consequently, the phenomena are considered by some to be the same.

'Dana's Manual of Minerology, sixteenth edition, 1955.