Spinel oxides with the formula AB2O4, are an important structural family of materials which exhibit a large variety of interesting and industrially relevant properties. We have recently synthesised a new inverse-spinel material ScMn2O4. In this compound, the tetrahedral site is occupied by Mn, while the octahedral site is randomly occupied by Mn and Sc. The magnetic properties of this new material are intriguing, owing to the combination of Mn2+ and Mn3+ ions. Using neutron diffraction we have determined that the system orders ferrimagnetically at 58K although the refined moment sizes are much smaller than expected and a substantial diffuse scattering is seen. Coupled with an anomalous peak in the low temperature magnetisation (not seen in diffraction) this presents a case for measuring the magnetic excitation spectrum above and below 7K to determine the nature of this anomaly.