Two commercially available amalgam alloy powders (one lathe-cut, the other spherical) were characterized in terms of density, surface area, particle size distribution and appearance under the scanning electron microscope. A third, experimental alloy powder, prepared by electrodeposition, was subjected to a similar analysis. It was found that particle size distribution can be a misleading indicator, in that when particles are porous, inordinately large amounts of mercury will be taken up on trituration, and the resulting amalgam will have wholly unsatisfactory mechanical properties. Surface area measured by BET (gas adsorption) may be the best single index of the morphological quality of an amalgam alloy powder.