Expedition to the Crystal Caverns

From publisher blurb: The Hydra Mega-Corporation has built a prototype "Hydra Drive" which can exceed previous records for high speed space travel. In order for this drive to work, however, a certain rare crystal is needed for fuel. So far this crystal has only been found on one world. That world is a hostile and formidable place. The travelers are offered a job collecting these crystals for substantial compensation.