Read, S.A.L.; Miller, S.A. 1980 Density testing of soft rocks in the laboratory - a review of methods and problems. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 342 30 p.
Abstract: Much of New Zealand is composed of sandstones, mudstones and siltstones of Tertiary age. The determination of the density, in particular dry density, of these soft rocks cannot be done in many cases using tehniques recommended for rocks due to their behaviour in the presence of water. The report reviews and summarises methods currently available for the determination of density of rocks and soils with attention to the measurement of volume and the water content at which it is determined. Using direct measurement, and the buoyancy principle on cores coated with saran resin, the dry density values of four soft rocks were determined when the natural water content was at or close to saturation and plotted close to the theoretical dry density v saturation water content curve. Values determined at other water contents varied with the method employed and the water content of the cores. A suggested method for the determination of the dry density of soft rocks is given in the appendix.