My dad had this book in his library and the cover was very memorable. The book was lost at some point and neither of us can remember the title or author. If I remember correctly, I believe the woman on the cover was riding some kind of motorcycle or hover bike (a bit reminiscent of the anime 'Akira'). I think the character was a crystal hunter. Thanks!
Further to MEGR's answer, the omnibus edition of the Crystal Singer series also featured the lady with the crystals as well as a better picture of the hovering bike;