Fission-track dating has been shown to be capable of dating certain glasses and crystalline materials from 20 years to several billion years of age, depending on the uranium content of the material. This dating method, in which the fraction of uranium impurity atoms that have spontaneously fissioned is measured by counting the resulting damage tracks (which are displayed by a simple chemical etching procedure), has shown several areas of usefulness for archaeology and prehistory. (1) Many ordinary man-made glasses as young as 2500 years contain enough uranium to be dated. (2) Special decorative glasses to which uranium has been added as a colorant may be dated if they were melted 20 years or more ago. (3) Natural glass artifacts which have been heated or remelted by man can be dated to give the time of heating. (4) The time of existence of a hominoid can be found by dating natural glass lava flows whose melting was contemporaneous. Illustrations of items (1) to (4) are present. Fission tracks produced by neutron irradiation provide a sensitive method of uranium detection and measurement in small samples of materials such as bone and glass, and allow the uranium distribution to be displayed graphically with a resolution of 0.0005 cm.