This paper investigates the impact of natural agglomerates on powder processing and consolidation through a comprehensive study of compaction of alumina powders of different particle size (ranging from 10 to 650 nm) and shape (spherical and irregular). The yield points of individual powders were determined from the green density-pressure relationship to ascertain the effect of initial particle size on agglomeration. The effect of surface modification by binder addition, which suppresses the significance of the initial particle size, was also studied. Diametral compression tests were carried out to estimate the green strength of the compacts. Results revealed that the green strength is strongly influenced not only by the initial particle size but also by the particle size distribution. The diametrically broken samples were subjected to fractographic studies followed by image analysis to calculate the agglomerate area fraction. The area fraction was found to be high for samples with low green strength and vice versa. (C) 2012 Elsevier B.V. All rights reserved.