Abstract: This paper presents a comparative study between the grindabiltiy of quartz by compression and impact forces as two different modes of size reduction in mineral comminution. The compression tests are carried out in a piston die, and the impact tests are performed using a stamp mill. Two quartz size fractions, (-6.3+4.75mm) and (-2.36+1.7mm) at sample weights of 150 and 100 grams were used for comparison of the behavior of quartz under the two different modes of material disintegration forces. The obtained results showed that the cumulative weight of the product size distributions is reasonably normalizable with respect to the median particle size, X50, for both compression and impact modes. The specific energy expended is inversely proportional to the median size of the products, and the reduction ratios (RR), X50f/X50p, are directly proportional to the applied forces in both grinding modes, and hence, to the specific energy expended. However, under the studied conditions, there is superiority of grinding by impact force, particularly at the high energy levels, over compression grinding in terms of reduction ratios and the fineness of the ground product. Analysis of the results points to conclusions concerning the choice of grinding equipment ensuring the most beneficial course of the size reduction process for a specific job.