Crystal Healer — S.L. Viehl

Now the intrepid surgeon combats a killer plague....

Genetically engineered interstellar surgeon Dr. Cherijo Torin, her husband, Duncan Reever, and a handpicked crew journey to the planet oKia to find a cure for the lethal black mineral that has caused suffering and death on too many worlds. While dealing with the primitive oKiaf and the fierce guardians protecting them, one of Cherijo's interns is infected, and his body slowly begins to crystallize.

As Cherijo races against time to save the young healer and free her crew from an oKiaf prison, mercenaries invade and threaten to destroy the world unless the healer surrenders to them. Cherijo must discover the crystals' secrets before the mercenaries use them to unleash an ancient unstoppable planet killer....