90s fantasy book, people turned into statues in crystal palace with mystery ending

[Maela]

I read this in the 90s (can't be more specific, sorry). The MC was a normal guy on a quest and he stumbles upon a crystal palace where all the inhabitants have been turned to stone/crystal statues. The whole book give you hints as to what happened but there's no ending.

The title was something like Crystal Palace. It was part of a grand promotion where the ending was not included in the book, but there was going to be some kinda raffle or sweepstakes or maybe mail your guess as to how it ended? And then there would be a way to get the reveal. But this was waaay before internet and I was a child, so there was no way I could send an entry and 30 years later i'm still bummed I don't know the ending!

[Kate]

Maeia ~~
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