I'm thinking I'd like to flavor my character as a kind of elemental spirit or animated statue, that the kobolds found guarding a dwarven temple and tricked into following them. Would that be OK? Although the mineral warrior doesn't technically change your type, it does give a burrow speed, the earth subtype, and DR/adamantine, which is a pretty radical change... That would also explain why he is so naive, weak-willed, etc.