Killashandra by Anne McCaffrey

This sequel to McCaffrey's Crystal Singer continues the story of Killashandra Ree, a failed musician whose perfect pitch has given her entree to the glamorous but dangerous profession of mining and cutting rare, valuable crystal. She is grateful for a new assignment that takes her off the oppressive crystal world of Ballybran, but when she arrives on Optheria to replace and tune the crystals of a famous organ, she steps into a new adventure. Abducted by the very subversives she had been trying to help, she eventually falls in love with one of her kidnappers and manages to uncover the Optherian Elders' subliminal brainwashing that had held the population captive and docile.