Seaweed Extract would also give more bang-for-the-buck than having to pay for rock dust plus shipping, and Seaweed gives the widest spectrum of known essential nutrients and useful nutrients, plus everything else that who knows whether it can be used. Seaweed also contains vitamins and growth-regulators useful to plants, that you would never get from rocks.
But if you have a cheap, convenient source of rock dust, by all means use it.