Yang, W; Parr, RG; Uytterhoeven, L, *New relation between hardness and compressibility of minerals*,
Physics and Chemistry of Minerals, vol. 15 no. 2
(1987),
pp. 191-195 [doi] .
**Abstract:**

*A relation between hardness (H) for minerals and compressibility (β) is proposed: {Mathematical expression}, where M is the molecular weight, ρ the density and q the number of atoms in a formula unit. The relation is derived from thermodynamics and is based on an analogy between mineral hardness and the concept of hardness assumed for the classification of reactivity of molecular species. It is confirmed with 27 elemental solids and 66 crystalline compounds, that this simple relation fairly well describes the trend of experimental hardnesses of minerals, and that the new relation has advantages over one earlier proposed [Plendl et al. (1965)] for connecting hardness to compressibility. © 1987 Springer-Verlag.*