The bulk density of soil depends greatly on the mineral make up of soil and the degree of compaction. The density of quartz is around 2.65 g/cm³ but the (dry) bulk density of a mineral soil is normally about half that density, between 1.0 and 1.6 g/cm³. In contrast, soils rich in soil organic carbon and some friable clays tend to have lower bulk densities (<1.0 g/cm³) due to a combination of the low-density of the organic materials themselves and increased porosity.