Since pure and intense yellow colors were not achieved in this Ni-karrooite system, we thought it could be interesting to
analyze the effect on coloring properties of accommodating Ni2+ ions in the octahedral sites of other closely-related Mg titanate structures of the same MgO:TiO2 system, namely the ilmenite (MgTiO3 geikielite) and spinel(Mg2TiO4 qandilite) compounds, with 1:1 and 2:1 Mg:Ti molar ratios respectively(1:2 in karrooite)
[17,18].