Cool, a mason powerleveling skill. That would make them more useful for sure.
Wtb Mason to place 10 diamond ore in my residence, where I will wait for a 100%+ bonus xp.
other issues: Miner double drops, looting picks.
serious: This would need a much higher xp loss reagent. Even if it was a level 60 skill (meaning the mason would only have about 4000xp to work with before losing the skill) I still predict powerleveling issues. Also, consider: placement of ore is usually not accurate as far as RP goes, it should be a very rare sight in a build.