The Center for High Performance Computing (HPC@UNM) provides a focus for high performance computing and communication at the University of New Mexico (UNM). HPC@UNM is committed to innovative research in computational and computer science with emphasis on both algorithm development and application. As part of this commitment, HPC@UNM sponsors this technical report series. The technical reports are subject to internal review by HPC@UNM. However, the material, as presented, does not necessarily reflect any position of HPC@UNM. Further, neither UNM, nor the HPC, makes any warranty or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information contained in this report. Abstract Conservation of linear and angular momenta, and conservation of energy are examined for the material-point method (MPM). It is shown that MPM can be formulated with implicit energy and momentum conserving mesh dynamics for hyperelastic materials. With a consistent mass matrix the resulting overall numerical method preserves the conservative properties of the mesh solution. Energy dissipation and angular momentum errors are also quantified for a lumped mass formulation. Properties of the method are illustrated in numerical examples.