When reasonably soluble substances (c* > 0.1 mol l(-1)) are crystallized at a high specific power input and within their metastable zone, attrition is a primary source of nucleation. The study presented here is an attempt to quantify this attrition mechanism. Firstly, a physical model is introduced which relates the attrition resistance of a crystalline substance to its mechanical properties. In the second part, the emphasis is placed on the determination of the relevant mechanical properties, hardness, elastic constants, and fracture resistance. The physical model will finally be compared to experimental results. A good agreement is found between the experimentally determined and theoretically predicted attrition behaviour.