Density, s, is the intrinsic unit mass of a material, defined as the mass of one cubic meter with units of kilograms per cubic meter (kg/m³).  However, the old cgs units of grams-per-cubic-centimeter are still widely used.  One gm/cc is equivalent to1,000 kg/m^3.

                                                                (1)

Figure 1.Density ranges in common materials.

in which subscripts f and m refer to the formation and the matrix, respectively, and S is the fractional water saturation.  A water density of 1,000 kg/m³ is assumed.  Figure 1 shows the density ranges of common materials.

The pages found under Properties are substantially based on a report produced by the United States Department of Transportation:

Wightman, W. E., Jalinoos, F., Sirles, P., and Hanna, K. (2003). "Application of Geophysical Methods to Highway Related Problems." Federal Highway Administration, Central Federal Lands Highway Division, Lakewood, CO, Publication No. FHWA-IF-04-021, September 2003. http://www.cflhd.gov/resources/agm/