The classical Raymer-Hunt-Gardner functional form , where and denote the P -wave velocity in the solid and pore-fluid phases, respectively, and ϕ is the total porosity, can also be used to relate the S-wave velocity in dry rock to porosity and mineralogy as , where is the S-wave velocity in the solid phase. Assuming that the shear modulus of rock does not depend on the pore fluid, in wet rock is , where and denote the bulk density of the dry and wet rock, respectively. This new functional form for prediction reiterates Nur's critical porosity concept: The ratio in dry rock equals that in the solid phase. It accurately predicts in consolidated clastic and carbonate rock. Two motivations for using it are (1) it is simple, and (2) it predicts not from but directly from ϕ and mineralogy.