Abrasive grain, grit size 60/90 is a coarse grit, (silicon carbide) for tumbling hard stones such as agates, jaspers, etc. An order of one will be one pound of grit. The amount of grit to use for tumbling with the 60/90 abrasive grit or coarse grit stage is approximately one tablespoon per pound of rock in your tumbler. Add fresh 60/90 abrasive grit each week, in the same amount until the stones are shaped or smoothed to your satisfaction. Course grit breaks down quickly and must be added again weekly or the grinding or smoothing process will stop. When checking the stones weekly to see if the majority are ready for the next grit stage, if more tumbling is needed in the course grit state, drain off a little water before adding more grit. No need to clean out the tumbler until the next grit stage, (150/220 abrasive grit or medium grit stage). Five pounds of 60/90 grit is available at a discount. Please check out the category, ” Lapidary Info” to learn more about tumbling your stones and the suggested steps and procedures.