Any numerical implementation requires the discretization of continuous functions into discrete approximations. These approximations are typically organized in a mesh, which defines boundaries, locations, and connectivity. Of specific interest to geophysical simulations, we require that averaging, interpolation and differential operators be defined for any mesh. In SimPEG, we have implemented a staggered mimetic finite volume approach (Hyman and Shashkov, 1999). This approach requires the definitions of variables at either cell-centers, nodes, faces, or edges as seen in the figure below.