Adamantine golems are among the rarest and most powerful of golems. Ideally, their indestructibility and resistance to magic should not be used just to stymie high-level characters (and their players), but as signposts toward storylines that are epic in scope.
The doors to the High Temple in Bez’lel, a city once famous for its clay marvels, have been shut for almost a decade. No bells have been struck, no oil lit, no incense burned, and no services held. Tomorrow the doors will open, and the scholar-priests will send their newly completed adamantine golem across the sea toward Rack, to crush the clockwork foundries there.
Just getting the adamantine required for a golem is an adventure. And on the Plane of Earth, it’s a race against time and petrifaction for three ice devils, a fey lord, and a troupe of dwarven summoners.
Adamantine golems are rare in the mortal realms, less so in the realms of the gods. The cat-pawed demigod of night burglars discovered this when he tried to steal a granite, seven-armed marilith statue from the vaults of the Lord of Murder.
—Pathfinder Bestiary 2 134