Stupid stupid stupid villains in this one. Which ruined the book for me.
Lets say you have a resource. Something with tremendous power and limitless applications that can only be collected by a person with an incredibly rare talent, 1 in million type thing. So if you happen to locate somebody with this ability, you'd absolutely send them out to collect this item in a way that will almost certainly kill them unnecessarily and in very short order, possibly before they can even get one of those objects you want so desperately. Makes perfect sense right?........ Oh wait NO IT DOESN'T!
You'd have to be a utter moron to waste a valuable resource like that. And it's exactly what the baddies in this one do. Go to great lengths to kidnap the heroine because of her special talents and then send her off into a volcano field to die of heatstroke and sun exposure as soon as she's been captured. No hat, no water, no suitable clothes and they tell her outright the conditions are going to kill her very quickly and that they want it that way. Any villain with sense would have figured out how to have her working for the next 50 years pulling those stones out of the cooling lava flows. But no, lets shoot the goose that lays the golden eggs and have a nice roast goose for dinner. Who needs gold eggs, you can't even eat them! If they villains in this were any stupider they'd be sitting in a corner drooling and chewing the furniture.
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In many books, the villains define the conflict that drives the story, if the bad guys are so imbecilic they couldn't put on a hat correctly it pretty much kills the story. Exactly what happened here.