Board Thread:Questions and Answers/@comment-79.79.222.60-20130506164210/@comment-7843903-20130507145722

the philo stone is very special because it has the ability to change blocks and the ability to change coal -> alchemical coal -> mobius fuel -> aeternalis fuel.

you can read more up on it here http://thetekkit.wikia.com/wiki/Philosopher's_Stone