To aid in the materials selection of gas control valves, the solid particle erosion behaviour of twelve metals was investigated using impinging jets of magnetite particles. The erosion rates were measured for two different particle sizes, two different velocities, and six different impingement angles. Scanning electron micrography and EDX (Energy Dispersive X-ray analysis) mapping was used to investigate the erosion mechanisms and the extent of particle embedding. There was no measurable erosion for the Tungsten Carbide samples, even for very long exposure times. For nickel plated steel, the plating was found to delaminate, resulting in a brittle erosive response. For all other tested materials, the measured erosion rates and scanning electron micrographs indicated a ductile erosion mechanism under all conditions considered. The erosion rates were found to fit a semi-empirical erosion model due to Oka et al.  well. The most erosion resistant materials were found to be the Solid tungsten carbide (WC) and Solid Stellite 12 and the least erosion resistant materials were A1018 carbon steel nickel plated and A240 Type 410 stainless steel plate. With all other conditions being equal, a larger erosion rate was measured when utilizing the smaller particles, than when the large particles were used. This counter-intuitive result was demonstrated to be due to a combination of effects, including the formation of thicker hardened layer more embedded particles, and more particle fragmentation when utilizing the larger particles.