Specific gravity, D

This is a measure of density. It is the ratio of the density of the substance being described (e.g. a mineral) to the density of water. Olivine has a specific density, D = 3.222, which means that olivine is 3.222 times more dense than water. Since water has a density of 1 g cm^-3, olivine has a density of 3.22 g cm^-3.