Based on observations of single impact studies of spherical coherent and agglomerate particles made from a wide range of materials, a classification of failure modes is presented involving low, intermedite. It is based on low, intermediate, and high velocity regimes. The work allows a point of reference for the expected failure modes under impact conditions of spherical particles made from many different materials. Interestingly, there is considerably greater diversity of modes in the low compared with the high velocity regimes. (C) 2004 Elsevier B.V. All rights reserved.