Rub two rough stones together – in a slow circular motion. Slow the sound down, enhance the bottom end. Gives you a real nice ancient tomb opening sound.
– Patrick Phelan
Big stone doors: Tape a mic to a brick (the physical contact is important). Heavily compress the mic and rub the brick against a paving stone. Sand and small gravel can be spread on the paving for variation. The result can be pitch shifted down to increase the perceived size of the door.
– Gordon Hall