Agrava was a planet which the Terran Federation mined vigorously for feldon crystals. It was uninhabited prior to the discovery of the crystals, at which point it quickly became heavily populated.
The Federation did not fully appreciate or understand the energy-harnessing potential of the crystals -- as a result, thousands of people on the planet were killed in a series of explosions. Kerr Avon would later point out that these lives likely would have been taken by the Federation sooner or later anyways, as the regime would want to dispose of anyone except "key personnel" for economical reasons.
Source
Agrava is derived from Blake's 7.