One pound coarse 60/80 grit for stage 1 rotary tumbling. DO NOT USE THIS in a vibratory tumbler, it is far too coarse.
Use 2-3 heaping tablespoons of grit per pound of rock. A good rule of thumb is that If you have noticeable grains of grit (not dust) left in the barrel at the end of 7 days, you can probably use slightly less going forward.