A new device has been developed to measure the Theological properties of rapidly sedimenting suspensions. The utility of this device is illustrated by measurements of Theological properties of magnetite suspensions used in dense media separation of coal. These suspensions are characterized by solids concentrations ranging from 10% to 2% by volume, corresponding to media densities of 1.4 to 2.0 g cm-3, respectively. The tow solids concentration, coarse particle sizes and high density of the material causes the media to settle too rapidly for accurate measurements to be made with conventional rheometers.