A pure glider generator (or simply glider generator) is a pattern that evolves into one or more gliders and nothing else. They are part of the cosmological classification of Life patterns. There was interest in this scheme early on, and within it on pure glider generators in particular (they were reported on quite frequently in the early issues of Lifeline, for example).
The 4-8-12 diamond and the bi-loaf[note 1] are two pure glider generators found by the Honeywell group in 1971. The former evolves into four gliders (one heading in each diagonal direction) in 15 generations, while the latter yields two after four ticks. Gliders from the bi-loaf run in opposite ways along the diagonal that is closest to the great axis of the pattern. E.g. when the great axis is NNE-SSW, the gliders' directions are northeast & southwest. The bi-clock is a later example found by Dale Edwin Cole in the same year. It consists of two closely placed clocks, and evolves into two gliders in two generations.
Mirage (or Fata Morgana) is a pure glider generator in which many sparse cells quickly create 13 gliders. Eight of those gliders construct a Gosper glider gun at generation 34, but the remaining five destroy the gun by generation 73. Similar patterns based on other glider syntheses can be constructed.