The magnetic properties of Ni 4 V 3 O 10 were explored with a sample produced by the hand grinding method to eliminate the contribution of any Fe 2 O 3 impurity. The field cooled (FC) and zero field cooled (ZFC) magnetization curves were measured between 2 and 400 K and are shown in Fig. . The most frequent impurity in Ni 4 V 3 O 10 samples, V 2-x Ni x O 3 , is a ferromagnet with an unreported magnetic structure. It has a Curie temperature of 142 K and an additional transition, here denoted T * , at 56 K. The FC curve for this impurity is shown in Fig. . Since a sharp increase in magnetization at T C occurs in any sample with a V 2-x Ni x O 3 impurity, we can be sure that the magnetization data in Figure is from Ni 4 V 3 O 10 alone. The bifurcation of the FC and ZFC curves in Fig. indicates a Néel temperature T N = 38 K. The broad hump centered below T N in the heat capacity data has been noted in other materials with magnetic frustration, site disorder, and complex coordination and oxidation chemistry. Table : Calculated band gaps for the 8 classes along with their relative calculated energies. Gap 1 (2) corresponds to the smallest band gap for spin component 1 (2